WorldWideScience

Sample records for spin valve device

  1. Inverse spin-valve effect in nanoscale Si-based spin-valve devices

    Science.gov (United States)

    Hiep, Duong Dinh; Tanaka, Masaaki; Hai, Pham Nam

    2017-12-01

    We investigated the spin-valve effect in nano-scale silicon (Si)-based spin-valve devices using a Fe/MgO/Ge spin injector/detector deposited on Si by molecular beam epitaxy. For a device with a 20 nm Si channel, we observed clear magnetoresistance up to 3% at low temperature when a magnetic field was applied in the film plane along the Si channel transport direction. A large spin-dependent output voltage of 20 mV was observed at a bias voltage of 0.9 V at 15 K, which is among the highest values in lateral spin-valve devices reported so far. Furthermore, we observed that the sign of the spin-valve effect is reversed at low temperatures, suggesting the possibility of a spin-blockade effect of defect states in the MgO/Ge tunneling barrier.

  2. Local spin valve effect in lateral (Ga,MnAs/GaAs spin Esaki diode devices

    Directory of Open Access Journals (Sweden)

    M. Ciorga

    2011-06-01

    Full Text Available We report here on a local spin valve effect observed unambiguously in lateral all-semiconductor all-electrical spin injection devices, employing p+ −(Ga,MnAs/n+ −GaAs Esaki diode structures as spin aligning contacts. We discuss the observed local spin-valve signal as a result of the interplay between spin-transport-related contribution and the tunneling anisotropic magnetoresistance of the magnetic contacts. The magnitude of the spin-related magnetoresistance change is equal to 30 Ω which is twice the magnitude of the measured non-local signal.

  3. Large spin-valve effect in a lateral spin-valve device based on ferromagnetic semiconductor GaMnAs

    Science.gov (United States)

    Asahara, Hirokatsu; Kanaki, Toshiki; Ohya, Shinobu; Tanaka, Masaaki

    2018-03-01

    We investigate the spin-dependent transport properties of a lateral spin-valve device based on the ferromagnetic semiconductor GaMnAs. This device is composed of a GaMnAs channel layer grown on GaAs with a narrow trench across the channel. Its current-voltage characteristics show tunneling behavior. Large magnetoresistance (MR) ratios of more than ˜10% are obtained. These values are much larger than those (˜0.1%) reported for lateral-type spin metal-oxide-semiconductor field-effect transistors. The magnetic field direction dependence of the MR curve differs from that of the anisotropic magnetoresistance of GaMnAs, which confirms that the MR signal originates from the spin-valve effect between the GaMnAs electrodes.

  4. Magnetoresistance Effect in NiFe/BP/NiFe Vertical Spin Valve Devices

    Directory of Open Access Journals (Sweden)

    Leilei Xu

    2017-01-01

    Full Text Available Two-dimensional (2D layered materials such as graphene and transition metal dichalcogenides are emerging candidates for spintronic applications. Here, we report magnetoresistance (MR properties of a black phosphorus (BP spin valve devices consisting of thin BP flakes contacted by NiFe ferromagnetic (FM electrodes. The spin valve effect has been observed from room temperature to 4 K, with MR magnitudes of 0.57% at 4 K and 0.23% at 300 K. In addition, the spin valve resistance is found to decrease monotonically as temperature is decreased, indicating that the BP thin film works as a conductive interlayer between the NiFe electrodes.

  5. A review on organic spintronic materials and devices: II. Magnetoresistance in organic spin valves and spin organic light emitting diodes

    Directory of Open Access Journals (Sweden)

    Rugang Geng

    2016-09-01

    Full Text Available In the preceding review paper, Paper I [Journal of Science: Advanced Materials and Devices 1 (2016 128–140], we showed the major experimental and theoretical studies on the first organic spintronic subject, namely organic magnetoresistance (OMAR in organic light emitting diodes (OLEDs. The topic has recently been of renewed interest as a result of a demonstration of the magneto-conductance (MC that exceeds 1000% at room temperature using a certain type of organic compounds and device operating condition. In this report, we will review two additional organic spintronic devices, namely organic spin valves (OSVs where only spin polarized holes exist to cause magnetoresistance (MR, and spin organic light emitting diodes (spin-OLEDs where both spin polarized holes and electrons are injected into the organic emissive layer to form a magneto-electroluminescence (MEL hysteretic loop. First, we outline the major advances in OSV studies for understanding the underlying physics of the spin transport mechanism in organic semiconductors (OSCs and the spin injection/detection at the organic/ferromagnet interface (spinterface. We also highlight some of outstanding challenges in this promising research field. Second, the first successful demonstration of spin-OLEDs is reviewed. We also discuss challenges to achieve the high performance devices. Finally, we suggest an outlook on the future of organic spintronics by using organic single crystals and aligned polymers for the spin transport layer, and a self-assembled monolayer to achieve more controllability for the spinterface.

  6. Gate-tunable large magnetoresistance in an all-semiconductor spin valve device.

    Science.gov (United States)

    Oltscher, M; Eberle, F; Kuczmik, T; Bayer, A; Schuh, D; Bougeard, D; Ciorga, M; Weiss, D

    2017-11-27

    A large spin-dependent and electric field-tunable magnetoresistance of a two-dimensional electron system is a key ingredient for the realization of many novel concepts for spin-based electronic devices. The low magnetoresistance observed during the last few decades in devices with lateral semiconducting transport channels between ferromagnetic source and drain contacts has been the main obstacle for realizing spin field effect transistor proposals. Here, we show both a large two-terminal magnetoresistance in a lateral spin valve device with a two-dimensional channel, with up to 80% resistance change, and tunability of the magnetoresistance by an electric gate. The enhanced magnetoresistance is due to finite electric field effects at the contact interface, which boost spin-to-charge conversion. The gating scheme that we use is based on switching between uni- and bidirectional spin diffusion, without resorting to spin-orbit coupling. Therefore, it can also be employed in materials with low spin-orbit coupling.

  7. Magnetism reflectometer study shows LiF layers improve efficiency in spin valve devices

    Energy Technology Data Exchange (ETDEWEB)

    Bardoel, Agatha A [ORNL; Lauter, Valeria [ORNL; Szulczewski, Greg J [ORNL

    2012-01-01

    New, more efficient materials for spin valves - a device used in magnetic sensors, random access memories, and hard disk drives - may be on the way based on research using the magnetism reflectometer at Oak Ridge National Laboratory (ORNL). Spin valve devices work by means of two or more conducting magnetic material layers that alternate their electrical resistance depending on the layers alignment. Giant magnetoresistance is a quantum mechanical effect first observed in thin film structures about 20 years ago. The effect is observed as a significant change in electrical resistance, depending on whether the magnetization of adjacent ferromagnetic layers is in a parallel or an antiparallel magnetic alignment. 'What we are doing here is developing new materials. The search for new materials suitable for injecting and transferring carriers with a preferential spin orientation is most important for the development of spintronics,' said Valeria Lauter, lead instrument scientist on the magnetism reflectometer at the Spallation Neutron Source (SNS), who collaborated on the experiment. The researchers discovered that the conductivity of such materials is improved when an organic polymer semiconductor layer is placed between the magnetic materials. Organic semiconductors are now the material of choice for future spin valve devices because they preserve spin coherence over longer times and distances than conventional semiconductors. While research into spin valves has been ongoing, research into organic semiconductors is recent. Previous research has shown that a 'conductivity mismatch' exists in spin valve systems in which ferromagnetic metal electrodes interface with such organic semiconductors as Alq3 ({pi}-conjugated molecule tris(8-hydroxy-quinoline) aluminium). This mismatch limits the efficient injection of the electrons from the electrodes at the interface with the semiconductor material. However, lithium fluoride (LiF), commonly used in light

  8. Performance of current-in-plane pseudo-spin-valve devices on CMOS silicon-on-insulator underlayers

    Science.gov (United States)

    Katti, R. R.; Zou, D.; Reed, D.; Schipper, D.; Hynes, O.; Shaw, G.; Kaakani, H.

    2003-05-01

    Prior work has shown that current-in-plane (CIP) giant magnetoresistive (GMR) pseudo-spin-valve (PSV) devices grown on bulk Si wafers and bulk complementary metal-oxide semiconductor (CMOS) underlayers exhibit write and read characteristics that are suitable for application as nonvolatile memory devices. In this work, CIP GMR PSV devices fabricated on silicon-on-insulator CMOS underlayers are shown to support write and read performance. Reading and writing fields for selected devices are shown to be approximately 25%-50% that of unselected devices, which provides a margin for reading and writing specific bits in a memory without overwriting bits and without disturbing other bits. The switching characteristics of experimental devices were compared to and found to be similar with Landau-Lifschitz-Gilbert micromagnetic modeling results, which allowed inferring regions of reversible and irreversible rotations in magnetic reversal processes.

  9. Nanosized perpendicular organic spin-valves

    Energy Technology Data Exchange (ETDEWEB)

    Göckeritz, Robert; Homonnay, Nico; Müller, Alexander; Richter, Tim [Institut für Physik, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale) (Germany); Fuhrmann, Bodo [Interdisziplinäres Zentrum für Materialwissenschaften, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale) (Germany); Schmidt, Georg, E-mail: georg.schmidt@physik.uni-halle.de [Institut für Physik, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale) (Germany); Interdisziplinäres Zentrum für Materialwissenschaften, Martin Luther University Halle-Wittenberg, 06099 Halle (Saale) (Germany)

    2015-03-09

    A fabrication process for perpendicular organic spin-valve devices based on the organic semiconductor Alq3 has been developed which offers the possibility to achieve active device areas of less than 500 × 500 nm{sup 2} and is flexible in terms of material choice for the active layers. Characterization of the resulting devices shows a large magnetoresistance of sometimes more than 100%, however with equally large variation from device to device. Comparison with large area spin-valves indicates that the magnetoresistance of both large and small devices most likely originates from tunneling through pinholes and tunneling magnetoresistance.

  10. Enhanced magnetoresistance in graphene spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Zahir, E-mail: zahir.upc@gmail.com [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa (Pakistan); Hussain, Ghulam [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa (Pakistan); Siddique, Salma [Department of Bioscience & Biotechnology, Sejong University, Seoul 143-747 (Korea, Republic of); Iqbal, Muhammad Waqas [Department of Physics, Riphah Institute of Computing and Applied Sciences (RICAS), Riphah International University, Lahore (Pakistan)

    2017-05-01

    Graphene has been explored as a promising candidate for spintronics due to its atomically flat structure and novel properties. Here we fabricate two spin valve junctions, one from directly grown graphene on Ni electrode (DG) and other from transferred graphene (TG). The magnetoresistance (MR) ratio for DG device is found to be higher than TG device i.e. ~0.73% and 0.14%, respectively. Also the spin polarization of Ni electrode is determined to be 6.03% at room temperature in case of DG device, however it reduces to 2.1% for TG device. From this analysis, we infer how environmental exposure of the sample degrades the spin properties of the magnetic junctions. Moreover, the transport measurements reveal linear behavior for current-voltage (I-V) characteristics, indicating ohmic behavior of the junctions. Our findings unveil the efficiency of direct growth of graphene for spin filtering mechanism in spin valve devices.

  11. Ultra-Compact 100 × 100 μm2 Footprint Hybrid Device with Spin-Valve Nanosensors

    Directory of Open Access Journals (Sweden)

    Diana C. Leitao

    2015-12-01

    Full Text Available Magnetic field mapping with micrometric spatial resolution and high sensitivity is a challenging application, and the technological solutions are usually based on large area devices integrating discrete magnetic flux guide elements. In this work we demonstrate a high performance hybrid device with improved field sensitivity levels and small footprint, consisting of a ultra-compact 2D design where nanometric spin valve sensors are inserted within the gap of thin-film magnetic flux concentrators. Pole-sensor distances down to 400 nm are demonstrated using nanofabrication techniques combined with an optimized liftoff process. These 100 × 100 μm 2 pixel sensors can be integrated in modular devices for surface mapping without moving parts.

  12. Spin injection and spin accumulation in all-metal mesoscopic spin valves

    NARCIS (Netherlands)

    Jedema, FJ; Nijboer, MS; Filip, AT; van Wees, BJ

    2003-01-01

    We study the electrical injection and detection of spin accumulation in lateral ferromagnetic-metal-nonmagnetic-metal-ferromagnetic-metal (F/N/F) spin valve devices with transparent interfaces. Different ferromagnetic metals, Permalloy (Py), cobalt (Co), and nickel (Ni), are used as electrical spin

  13. Interlayer quality dependent graphene spin valve

    International Nuclear Information System (INIS)

    Iqbal, Muhammad Zahir; Hussain, Ghulam; Siddique, Salma; Iqbal, Muhammad Waqas; Murtaza, Ghulam; Ramay, Shahid Mahmood

    2017-01-01

    It is possible to utilize the new class of materials for emerging two-dimensional (2D) spintronic applications. Here, the role of defects in the graphene interlayer and its influence on the spin valve signal is reported. The emergence of D peak in Raman spectrum reveals defects in the graphene layer. The linear I-V curve for defective and non-defective graphene samples indicate the ohmic nature of NiFe and graphene contact. A non-uniform magnetoresistive effect with a bump is persistently observed for defective graphene device at various temperatures, while a smooth and symmetric signal is detected for non-defective graphene spin valve. Parallel and antiparallel alignments of magnetization of magnetic materials shows low and high resistance states, respectively. The magnetoresistance (MR) ratio for defective graphene NiFe/graphene/NiFe spin valve is measured to be ~0.16% at 300 K which progresses to ~0.39% for non-defective graphene device at the same temperature. Similarly at 4.2 K the MR ratios are reported to be ~0.41% and ~0.78% for defective and non-defective graphene devices, respectively. Our investigation provides an evidence for relatively better response of the spin valve signal with high quality graphene interlayer.

  14. Interlayer quality dependent graphene spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Zahir, E-mail: zahir.upc@gmail.com [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi, Khyber Pakhtunkhwa, 23640 Pakistan (Pakistan); Hussain, Ghulam [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi, Khyber Pakhtunkhwa, 23640 Pakistan (Pakistan); Siddique, Salma [Department of Bioscience & Biotechnology, Sejong University, Seoul, 143-747 (Korea, Republic of); Iqbal, Muhammad Waqas [Department of Physics, Riphah Institute of Computing and Applied Sciences (RICAS), Riphah International University, Lahore (Pakistan); Murtaza, Ghulam [Centre for Advanced Studies in Physics, Government College University, Lahore 54000 (Pakistan); Ramay, Shahid Mahmood [Physics & Astronomy Department, College of Science, King Saud University, Riyadh 11451 (Saudi Arabia)

    2017-01-15

    It is possible to utilize the new class of materials for emerging two-dimensional (2D) spintronic applications. Here, the role of defects in the graphene interlayer and its influence on the spin valve signal is reported. The emergence of D peak in Raman spectrum reveals defects in the graphene layer. The linear I-V curve for defective and non-defective graphene samples indicate the ohmic nature of NiFe and graphene contact. A non-uniform magnetoresistive effect with a bump is persistently observed for defective graphene device at various temperatures, while a smooth and symmetric signal is detected for non-defective graphene spin valve. Parallel and antiparallel alignments of magnetization of magnetic materials shows low and high resistance states, respectively. The magnetoresistance (MR) ratio for defective graphene NiFe/graphene/NiFe spin valve is measured to be ~0.16% at 300 K which progresses to ~0.39% for non-defective graphene device at the same temperature. Similarly at 4.2 K the MR ratios are reported to be ~0.41% and ~0.78% for defective and non-defective graphene devices, respectively. Our investigation provides an evidence for relatively better response of the spin valve signal with high quality graphene interlayer.

  15. Absence of hyperfine effects in 13C-graphene spin-valve devices

    NARCIS (Netherlands)

    Wojtaszek, M.; Vera-Marun, I.J.; Whiteway, E.; Hilke, M.; Wees, B.J. van

    2014-01-01

    The carbon isotope 13C, in contrast to 12C, possesses a nuclear magnetic moment and can induce electron spin dephasing in graphene. This effect is usually neglected due to the low abundance of 13C in natural carbon allotropes (~1%). Chemical vapor deposition (CVD) allows for artificial synthesis of

  16. Spin-Valve Effect in a Ni-C60-Ni Device

    National Research Council Canada - National Science Library

    He, Haiying; Pandey, Ravindra; Karna, Shashi P

    2006-01-01

    .... The magnitude of the junction magnetoresistance (JMR) is found to be significantly large for the device, which makes it a promising candidate for realistic applications in molecular spintronics...

  17. Spin Switching via Quantum Dot Spin Valves

    Science.gov (United States)

    Gergs, N. M.; Bender, S. A.; Duine, R. A.; Schuricht, D.

    2018-01-01

    We develop a theory for spin transport and magnetization dynamics in a quantum dot spin valve, i.e., two magnetic reservoirs coupled to a quantum dot. Our theory is able to take into account effects of strong correlations. We demonstrate that, as a result of these strong correlations, the dot gate voltage enables control over the current-induced torques on the magnets and, in particular, enables voltage-controlled magnetic switching. The electrical resistance of the structure can be used to read out the magnetic state. Our model may be realized by a number of experimental systems, including magnetic scanning-tunneling microscope tips and artificial quantum dot systems.

  18. Spin-dependent Seebeck coefficients of Ni80Fe20 and Co in nanopillar spin valves

    NARCIS (Netherlands)

    Dejene, F. K.; Flipse, J.; van Wees, B. J.

    2012-01-01

    We have experimentally determined the spin-dependent Seebeck coefficient of permalloy (Ni80Fe20) and cobalt (Co) using nanopillar spin valve devices, a stack of two ferromagnetic layers separated by a nonmagnetic layer. The devices were specifically designed to separate heat-related effects from

  19. Spin motive forces, 'measurements', and spin-valves

    International Nuclear Information System (INIS)

    Barnes, S.E.

    2007-01-01

    Discussed is the spin motive force (smf) produced by a spin valve, this reflecting its dynamics. Relaxation implies an implicit measurement of the magnetization of the free layer of a valve. It is shown this has implications for the angular dependence of the torque transfer. Some discussion of recent experiments is included

  20. Inverse Magnetoresistance in Polymer Spin Valves.

    Science.gov (United States)

    Ding, Shuaishuai; Tian, Yuan; Li, Yang; Mi, Wenbo; Dong, Huanli; Zhang, Xiaotao; Hu, Wenping; Zhu, Daoben

    2017-05-10

    In this work, both negative and positive magnetoresistance (MR) in solution-processed regioregular poly(3-hexylthiophene) (RR-P3HT) is observed in organic spin valves (OSVs) with vertical La 2/3 Sr 1/3 MnO 3 (LSMO)/P3HT/AlO x /Co configuration. The ferromagnetic (FM) LSMO electrode with near-atomic flatness is fabricated by a DC facing-target magnetron sputtering method. This research is focused on the origin of the MR inversion. Two types of devices are investigated in details: One with Co penetration shows a negative MR of 0.2%, while the other well-defined device with a nonlinear behavior has a positive MR of 15.6%. The MR measurements in LSMO/AlO x /Co and LSMO/Co junctions are carried to exclude the interference of insulating layer and two FM electrodes themselves. By examining the Co thicknesses and their corresponding magnetic hysteresis loops, a spin-dependent hybrid-interface-state model by Co penetration is induced to explain the MR sign inversion. These results proven by density functional theory (DFT) calculations may shed light on the controllable interfacial properties in designing novel OSV devices.

  1. Flexible semi-transparent organic spin valve based on bathocuproine

    International Nuclear Information System (INIS)

    Sun, Xiangnan; Bedoya-Pinto, Amilcar; Llopis, Roger; Casanova, Fèlix; Hueso, Luis E.

    2014-01-01

    Organic semiconductors are attractive materials for advanced spintronic applications due to their long spin lifetimes and, simultaneously, their mechanical flexibility. With the aim of combining these advantages in a single device, we report on the fabrication and properties of a mechanically flexible bathocuproine-based spin valve. This organic spin device shows great stability on both electrical and magneto-transport properties upon mechanical bending at different radius (up to r = 5 mm), while featuring long-lasting endurance (on bending over 50 times). The room-temperature magnetoresistance ratio reaches up to 3.5%, and is notably preserved under air atmosphere. The observation of spin transport at room-temperature, combined with the outstanding mechanical properties and air stability, highlights the potential of bathocuproine-based spin devices towards applications.

  2. Spin transport at high temperatures in epitaxial Heusler alloy/n-GaAs lateral spin valves

    Science.gov (United States)

    Peterson, Timothy A.; Christie, Kevin D.; Patel, Sahil J.; Crowell, Paul A.; Palmstrøm, Chris J.

    2015-03-01

    We report on electrical injection and detection of spin accumulation in ferromagnet/ n-GaAs lateral spin-valve devices, observed up to and above room temperature. The ferromagnet in these measurements is the Heusler alloy Co2FeSi, and the semiconductor channel is GaAs doped at 3 ×1016 cm-3. The spin signal is enhanced by operating the detection contact under forward bias. The enhancement originates from drift effects at low-temperatures and an increase of the detection efficiency at all temperatures. The detector bias dependence of the observed spin-valve signal is interpreted by taking into account the quantum well (QW) which forms in the degenerately doped region immediately behind the Schottky tunnel barrier. In particular, we believe the QW is responsible for the minority spin accumulation (majority spin current) under large forward bias. The spin diffusion length and lifetime are determined by measuring the separation dependence of the non-local spin valve signal in a family of devices patterned by electron beam lithography. A spin diffusion length of 700 nm and lifetime of 46 picoseconds are found at a temperature of 295 K. This work was supported by the NSF under DMR-1104951, the NSF MRSEC program and C-SPIN, a SRC STARNET center sponsored by MARCO and DARPA.

  3. Magnon detection using a ferroic collinear multilayer spin valve.

    Science.gov (United States)

    Cramer, Joel; Fuhrmann, Felix; Ritzmann, Ulrike; Gall, Vanessa; Niizeki, Tomohiko; Ramos, Rafael; Qiu, Zhiyong; Hou, Dazhi; Kikkawa, Takashi; Sinova, Jairo; Nowak, Ulrich; Saitoh, Eiji; Kläui, Mathias

    2018-03-14

    Information transport and processing by pure magnonic spin currents in insulators is a promising alternative to conventional charge-current-driven spintronic devices. The absence of Joule heating and reduced spin wave damping in insulating ferromagnets have been suggested for implementing efficient logic devices. After the successful demonstration of a majority gate based on the superposition of spin waves, further components are required to perform complex logic operations. Here, we report on magnetization orientation-dependent spin current detection signals in collinear magnetic multilayers inspired by the functionality of a conventional spin valve. In Y 3 Fe 5 O 12 |CoO|Co, we find that the detection amplitude of spin currents emitted by ferromagnetic resonance spin pumping depends on the relative alignment of the Y 3 Fe 5 O 12 and Co magnetization. This yields a spin valve-like behavior with an amplitude change of 120% in our systems. We demonstrate the reliability of the effect and identify its origin by both temperature-dependent and power-dependent measurements.

  4. Spin Valve Systems for Angle Sensor Applications

    OpenAIRE

    Johnson, Andrew

    2004-01-01

    A contact-less sensor with the ability to measure over a 360° range has been long sought after in the automotive industry. Such a sensor could be realized by utilizing the angle dependence of the Giant Magneto Resistance (GMR) Effect in a special type of magnetic multilayer called a spin valve arranged in a wheatstone bridge circuit [Spo96]. A spin valve consists of two ferromagnetic layers separated by nonmagnetic spacer layer where the magnetization of one of the ferromagnetic layers is pin...

  5. Graphene spin valve: An angle sensor

    Energy Technology Data Exchange (ETDEWEB)

    Iqbal, Muhammad Zahir, E-mail: zahir.upc@gmail.com [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa (Pakistan); Hussain, Ghulam [Faculty of Engineering Sciences, GIK Institute of Engineering Sciences and Technology, Topi 23640, Khyber Pakhtunkhwa (Pakistan); Siddique, Salma [Department of Bioscience & Biotechnology, Sejong University, Seoul 143-747 (Korea, Republic of); Iqbal, Muhammad Waqas [Department of Physics, Riphah Institute of Computing and Applied Sciences (RICAS), Riphah International University, Lahore (Pakistan)

    2017-06-15

    Graphene spin valves can be optimized for various spintronic applications by tuning the associated experimental parameters. In this work, we report the angle dependent magnetoresistance (MR) in graphene spin valve for different orientations of applied magnetic field (B). The switching points of spin valve signals show a clear shift towards higher B for each increasing angle of the applied field, thus sensing the response for respective orientation of the magnetic field. The angular variation of B shifts the switching points from ±95 G to ±925 G as the angle is varied from 0° to 90° at 300 K. The observed shifts in switching points become more pronounced (±165 G to ±1450 G) at 4.2 K for similar orientation. A monotonic increase in MR ratio is observed as the angle of magnetic field is varied in the vertical direction at 300 K and 4.2 K temperatures. This variation of B (from 0° to 90°) increases the magnitude of MR ratio from ∼0.08% to ∼0.14% at 300 K, while at 4.2 K it progresses to ∼0.39% from ∼0.14%. The sensitivity related to angular variation of such spin valve structure can be employed for angle sensing applications.

  6. Spin injection and detection in lateral spin valves with hybrid interfaces

    Science.gov (United States)

    Wang, Le; Liu, Wenyu; Ying, Hao; Chen, Luchen; Lu, Zhanjie; Han, Shuo; Chen, Shanshan; Zhao, Bing; Xu, Xiaoguang; Jiang, Yong

    2018-06-01

    Spin injection and detection in lateral spin valves with hybrid interfaces comprising a Co/Ag transparent contact and a Co/MgO/Ag junction (III) are investigated at room temperature in comparison with pure Co/Ag transparent contacts (I) and Co/MgO/Ag junctions (II). The measured spin-accumulation signals of a type III device are five times higher than those for type I. The extracted spin diffusion length in Ag is 180 nm for all three types of devices. The enhancement of the spin signal of the hybrid structure is mainly attributed to the increase of the interfacial spin polarization from the Co/MgO/Ag junction.

  7. Spin current through quantum-dot spin valves

    International Nuclear Information System (INIS)

    Wang, J; Xing, D Y

    2006-01-01

    We report a theoretical study of the influence of the Coulomb interaction on the equilibrium spin current in a quantum-dot spin valve, in which the quantum dot described by the Anderson impurity model is coupled to two ferromagnetic leads with noncollinear magnetizations. In the Kondo regime, electrons transmit through the quantum dot via higher-order virtual processes, in which the spin of either lead electrons or a localized electron on the quantum dot may reverse. It is found that the magnitude of the spin current decreases with increasing Coulomb interactions due to spin flip effects on the dot. However, the spatial direction of the spin current remains unchanged; it is determined only by the exchange coupling between two noncollinear magnetizations

  8. Current-induced magnetization changes in a spin valve due to incoherent emission of non-equilibrium magnons

    OpenAIRE

    Kozub, V. I.; Caro, J.

    2004-01-01

    We describe spin transfer in a ferromagnet/normal metal/ferromagnet spin-valve point contact. Spin is transferred from the spin-polarized device current to the magnetization of the free layer by the mechanism of incoherent magnon emission by electrons. Our approach is based on the rate equation for the magnon occupation, using Fermi's golden rule for magnon emission and absorption and the non-equilibrium electron distribution for a biased spin valve. The magnon emission reduces the magnetizat...

  9. Improved corrosion resistance of spin-valve film

    International Nuclear Information System (INIS)

    Tetsukawa, H.; Hommura, H.; Okabe, A.; Soda, Y.

    2007-01-01

    We investigated the corrosion behavior and magnetoresistance of spin-valve film in order to improve the corrosion resistance of the spin-valve head for a tape recording system. The conventional spin-valve head (sub./Ta/NiFe/CoFe/Cu/CoFe/PtMn/Ta) with no diamond-like carbon (DLC) protective layer showed poor corrosion resistance. This is because the CoFe for ferromagnetic layer and Cu for spacer in the spin-valve film exhibited poor corrosion resistance. The corrosion resistance of the CoFe film and Cu film improved with the addition of Ni and Au, respectively. The spin-valve film (sub./Ta/NiFe/CoNiFe/CuAu/CoNiFe/PtMn/Ta) showed higher pitting potential than the conventional spin-valve film by +0.45 V. This presents a significant improvement over the conventional spin-valve film. We also investigated the effect of the composition of ferromagnetic layer and spacer on the magnetoresistance of the spin-valve film. The magnetoresistance of the spin-valve film by substitution of CoNiFe for CoFe in ferromagnetic layer decreased slightly. The magnetoresistance of the spin-valve film decreased as the addition of Au of the spacer increased. The diffusion at CoNiFe/CuAu interface has not been observed in annealing process. The quantitative relation between corrosion resistance and magnetoresistance of spin-valve film, and its ferromagnetic layer and spacer's compositions have been clarified. The output voltage at 50 Oe of the corrosion-resistant spin-valve head with CoNiFe ferromagnetic layer and CuAu spacer was about 50% of that of the conventional spin-valve head

  10. Improved corrosion resistance of spin-valve film

    Energy Technology Data Exchange (ETDEWEB)

    Tetsukawa, H. [Sony Corporation, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141-0001 (Japan)]. E-mail: tetsukaw@arc.sony.co.jp; Hommura, H. [Sony Corporation, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141-0001 (Japan); Okabe, A. [Sony Corporation, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141-0001 (Japan); Soda, Y. [Sony Corporation, 6-7-35 Kitashinagawa, Shinagawa-ku, Tokyo 141-0001 (Japan)

    2007-06-15

    We investigated the corrosion behavior and magnetoresistance of spin-valve film in order to improve the corrosion resistance of the spin-valve head for a tape recording system. The conventional spin-valve head (sub./Ta/NiFe/CoFe/Cu/CoFe/PtMn/Ta) with no diamond-like carbon (DLC) protective layer showed poor corrosion resistance. This is because the CoFe for ferromagnetic layer and Cu for spacer in the spin-valve film exhibited poor corrosion resistance. The corrosion resistance of the CoFe film and Cu film improved with the addition of Ni and Au, respectively. The spin-valve film (sub./Ta/NiFe/CoNiFe/CuAu/CoNiFe/PtMn/Ta) showed higher pitting potential than the conventional spin-valve film by +0.45 V. This presents a significant improvement over the conventional spin-valve film. We also investigated the effect of the composition of ferromagnetic layer and spacer on the magnetoresistance of the spin-valve film. The magnetoresistance of the spin-valve film by substitution of CoNiFe for CoFe in ferromagnetic layer decreased slightly. The magnetoresistance of the spin-valve film decreased as the addition of Au of the spacer increased. The diffusion at CoNiFe/CuAu interface has not been observed in annealing process. The quantitative relation between corrosion resistance and magnetoresistance of spin-valve film, and its ferromagnetic layer and spacer's compositions have been clarified. The output voltage at 50 Oe of the corrosion-resistant spin-valve head with CoNiFe ferromagnetic layer and CuAu spacer was about 50% of that of the conventional spin-valve head.

  11. Simple Check Valves for Microfluidic Devices

    Science.gov (United States)

    Willis, Peter A.; Greer, Harold F.; Smith, J. Anthony

    2010-01-01

    A simple design concept for check valves has been adopted for microfluidic devices that consist mostly of (1) deformable fluorocarbon polymer membranes sandwiched between (2) borosilicate float glass wafers into which channels, valve seats, and holes have been etched. The first microfluidic devices in which these check valves are intended to be used are micro-capillary electrophoresis (microCE) devices undergoing development for use on Mars in detecting compounds indicative of life. In this application, it will be necessary to store some liquid samples in reservoirs in the devices for subsequent laboratory analysis, and check valves are needed to prevent cross-contamination of the samples. The simple check-valve design concept is also applicable to other microfluidic devices and to fluidic devices in general. These check valves are simplified microscopic versions of conventional rubber- flap check valves that are parts of numerous industrial and consumer products. These check valves are fabricated, not as separate components, but as integral parts of microfluidic devices. A check valve according to this concept consists of suitably shaped portions of a deformable membrane and the two glass wafers between which the membrane is sandwiched (see figure). The valve flap is formed by making an approximately semicircular cut in the membrane. The flap is centered over a hole in the lower glass wafer, through which hole the liquid in question is intended to flow upward into a wider hole, channel, or reservoir in the upper glass wafer. The radius of the cut exceeds the radius of the hole by an amount large enough to prevent settling of the flap into the hole. As in a conventional rubber-flap check valve, back pressure in the liquid pushes the flap against the valve seat (in this case, the valve seat is the adjacent surface of the lower glass wafer), thereby forming a seal that prevents backflow.

  12. Magnetic structure of the spin valve interface

    International Nuclear Information System (INIS)

    Nicholson, D.M.C.; Butler, W.H.; Zhang, X.; MacLaren, J.M.; Gurney, B.A.; Speriosu, V.S.

    1994-01-01

    Nonferromagnetic atoms present at Ni/Cu and Permalloy/Cu interfaces in sputtered spin valve magnetoresistive layered structures have been shown to cause reduced magnetoresistance. Here we show that a model in which the moments on the Ni atoms in the interfacial region of Ni/Cu are reduced substantially by interdiffusion with Cu is consistent with the experimental results. In contrast, we believe that moments persist at the permalloy/Cu interface, which first principle total energy calculations suggest will be disordered at finite temperatures. These reduced or disordered moments are expected to significantly reduce the GMR

  13. Topological Material-Based Spin Devices

    Science.gov (United States)

    Zhang, Minhao; Wang, Xuefeng

    Three-dimensional topological insulators have insulating bulk and gapless helical surface states. One of the most fascinating properties of the metallic surface states is the spin-momentum helical locking. The giant current-driven torques on the magnetic layer have been discovered in TI/ferromagnet bilayers originating from the spin-momentum helical locking, enabling the efficient magnetization switching with a low current density. We demonstrated the current-direction dependent on-off state in TIs-based spin valve devices for memory and logic applications. Further, we demonstrated the Bi2Se3 system will go from a topologically nontrivial state to a topologically trivial state when Bi atoms are replaced by lighter In atoms. Here, topologically trivial metal (BixIny)2 Se3 with high mobility also facilitates the realization of its application in multifunctional spintronic devices.

  14. The effect of electrodes on 11 acene molecular spin valve: Semi-empirical study

    Science.gov (United States)

    Aadhityan, A.; Preferencial Kala, C.; John Thiruvadigal, D.

    2017-10-01

    A new revolution in electronics is molecular spintronics, with the contemporary evolution of the two novel disciplines of spintronics and molecular electronics. The key point is the creation of molecular spin valve which consists of a diamagnetic molecule in between two magnetic leads. In this paper, non-equilibrium Green's function (NEGF) combined with Extended Huckel Theory (EHT); a semi-empirical approach is used to analyse the electron transport characteristics of 11 acene molecular spin valve. We examine the spin-dependence transport on 11 acene molecular junction with various semi-infinite electrodes as Iron, Cobalt and Nickel. To analyse the spin-dependence transport properties the left and right electrodes are joined to the central region in parallel and anti-parallel configurations. We computed spin polarised device density of states, projected device density of states of carbon and the electrode element, and transmission of these devices. The results demonstrate that the effect of electrodes modifying the spin-dependence behaviours of these systems in a controlled way. In Parallel and anti-parallel configuration the separation of spin up and spin down is lager in the case of iron electrode than nickel and cobalt electrodes. It shows that iron is the best electrode for 11 acene spin valve device. Our theoretical results are reasonably impressive and trigger our motivation for comprehending the transport properties of these molecular-sized contacts.

  15. Spin current and spin transfer torque in ferromagnet/superconductor spin valves

    Science.gov (United States)

    Moen, Evan; Valls, Oriol T.

    2018-05-01

    Using fully self-consistent methods, we study spin transport in fabricable spin valve systems consisting of two magnetic layers, a superconducting layer, and a spacer normal layer between the ferromagnets. Our methods ensure that the proper relations between spin current gradients and spin transfer torques are satisfied. We present results as a function of geometrical parameters, interfacial barrier values, misalignment angle between the ferromagnets, and bias voltage. Our main results are for the spin current and spin accumulation as functions of position within the spin valve structure. We see precession of the spin current about the exchange fields within the ferromagnets, and penetration of the spin current into the superconductor for biases greater than the critical bias, defined in the text. The spin accumulation exhibits oscillating behavior in the normal metal, with a strong dependence on the physical parameters both as to the structure and formation of the peaks. We also study the bias dependence of the spatially averaged spin transfer torque and spin accumulation. We examine the critical-bias effect of these quantities, and their dependence on the physical parameters. Our results are predictive of the outcome of future experiments, as they take into account imperfect interfaces and a realistic geometry.

  16. Interplay of Peltier and Seebeck Effects in Nanoscale Nonlocal Spin Valves

    NARCIS (Netherlands)

    Bakker, F. L.; Slachter, A.; Adam, J-P; van Wees, B. J.

    2010-01-01

    We have experimentally studied the role of thermoelectric effects in nanoscale nonlocal spin valve devices. A finite element thermoelectric model is developed to calculate the generated Seebeck voltages due to Peltier and Joule heating in the devices. By measuring the first, second, and third

  17. Autonomous booster device of a safety valve

    International Nuclear Information System (INIS)

    Namand, H.

    1983-01-01

    The invention concerns an autonomous booster device of a protection safety valve of a pressure vessel. The valve comprises a hollow structure, a seat connected with a mobile flap forming one piece with a stem and a calibration spring bearing on the stem and on the valve structure to maintain the flap bearing on the seat. The stem of the flap is prolongated in a box forming one piece with the valve structure and receives an added push of a spring. The box acts as a pressure device of which the piston can exercise on the stem a push opposite to and larger than the spring one. The feeding device of the pressure box is finally described in detail [fr

  18. Aging effect of spin accumulation in non-local spin valves

    International Nuclear Information System (INIS)

    Zhao, Bing; Zhang, Ziyu; Chen, Xiaobing; Zhang, Xiaohan; Pan, Jiahui; Ma, Jiajun; Li, Juan; Wang, Zhicheng; Wang, Le; Xu, Xiaoguang; Jiang, Yong

    2017-01-01

    Highlights: • First time to reveal the whole temporal evolution life of spintronics devices. • The gradual oxidation of the junctions’ areas and that of the channel are confirmed to be the predominant factors to determine the temporal evolution. • Physically, the temporal evolution can be evaluated by theories of S. Takahashi and A. Fert. • This study may offer some useful advice for the design and protection of future industrial spintronics devices. - Abstract: A temporal evolution of spin accumulation of Co/MgO/Ag spin valves have been studied by using the nonlocal spin detection technique over almost a 3-month period in the ambient environment after the fabrication of the devices. Three different stages of the spin accumulation are first observed due to aging effect. The aging effect comes from two contributions–the gradual oxidation of the Ag/MgO and MgO/Co interfaces at the junctions’ areas which arises from the annealing process and the oxidation of the side surfaces of the Ag channels. The theories of S. Takahashi and A. Fert are introduced to evaluate the different evolution stages of spin accumulation.

  19. Aging effect of spin accumulation in non-local spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Bing; Zhang, Ziyu; Chen, Xiaobing; Zhang, Xiaohan; Pan, Jiahui; Ma, Jiajun; Li, Juan; Wang, Zhicheng [State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Wang, Le, E-mail: wangle@ruc.edu.cn [Department of Physics, Renmin University of China, Beijing 100872 (China); Xu, Xiaoguang, E-mail: xgxu@ustb.edu.cn [State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Jiang, Yong [State Key Laboratory for Advanced Metals and Materials, School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

    2017-06-15

    Highlights: • First time to reveal the whole temporal evolution life of spintronics devices. • The gradual oxidation of the junctions’ areas and that of the channel are confirmed to be the predominant factors to determine the temporal evolution. • Physically, the temporal evolution can be evaluated by theories of S. Takahashi and A. Fert. • This study may offer some useful advice for the design and protection of future industrial spintronics devices. - Abstract: A temporal evolution of spin accumulation of Co/MgO/Ag spin valves have been studied by using the nonlocal spin detection technique over almost a 3-month period in the ambient environment after the fabrication of the devices. Three different stages of the spin accumulation are first observed due to aging effect. The aging effect comes from two contributions–the gradual oxidation of the Ag/MgO and MgO/Co interfaces at the junctions’ areas which arises from the annealing process and the oxidation of the side surfaces of the Ag channels. The theories of S. Takahashi and A. Fert are introduced to evaluate the different evolution stages of spin accumulation.

  20. Large spin current injection in nano-pillar-based lateral spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Nomura, Tatsuya [Department of Physics, Kyushu University, 744 Motooka, Fukuoka, 819-0395 (Japan); Ohnishi, Kohei; Kimura, Takashi, E-mail: t-kimu@phys.kyushu-u.ac.jp [Department of Physics, Kyushu University, 744 Motooka, Fukuoka, 819-0395 (Japan); Research Center for Quantum Nano-Spin Sciences, Kyushu University, 744 Motooka, Fukuoka, 819-0395 (Japan)

    2016-08-26

    We have investigated the influence of the injection of a large pure spin current on a magnetization process of a non-locally located ferromagnetic dot in nano-pillar-based lateral spin valves. Here, we prepared two kinds of the nano-pillar-type lateral spin valve based on Py nanodots and CoFeAl nanodots fabricated on a Cu film. In the Py/Cu lateral spin valve, although any significant change of the magnetization process of the Py nanodot has not been observed at room temperature. The magnetization reversal process is found to be modified by injecting a large pure spin current at 77 K. Switching the magnetization by the nonlocal spin injection has also been demonstrated at 77 K. In the CoFeAl/Cu lateral spin valve, a room temperature spin valve signal was strongly enhanced from the Py/Cu lateral spin valve because of the highly spin-polarized CoFeAl electrodes. The room temperature nonlocal switching has been demonstrated in the CoFeAl/Cu lateral spin valve.

  1. Energy efficient hybrid computing systems using spin devices

    Science.gov (United States)

    Sharad, Mrigank

    Emerging spin-devices like magnetic tunnel junctions (MTJ's), spin-valves and domain wall magnets (DWM) have opened new avenues for spin-based logic design. This work explored potential computing applications which can exploit such devices for higher energy-efficiency and performance. The proposed applications involve hybrid design schemes, where charge-based devices supplement the spin-devices, to gain large benefits at the system level. As an example, lateral spin valves (LSV) involve switching of nanomagnets using spin-polarized current injection through a metallic channel such as Cu. Such spin-torque based devices possess several interesting properties that can be exploited for ultra-low power computation. Analog characteristic of spin current facilitate non-Boolean computation like majority evaluation that can be used to model a neuron. The magneto-metallic neurons can operate at ultra-low terminal voltage of ˜20mV, thereby resulting in small computation power. Moreover, since nano-magnets inherently act as memory elements, these devices can facilitate integration of logic and memory in interesting ways. The spin based neurons can be integrated with CMOS and other emerging devices leading to different classes of neuromorphic/non-Von-Neumann architectures. The spin-based designs involve `mixed-mode' processing and hence can provide very compact and ultra-low energy solutions for complex computation blocks, both digital as well as analog. Such low-power, hybrid designs can be suitable for various data processing applications like cognitive computing, associative memory, and currentmode on-chip global interconnects. Simulation results for these applications based on device-circuit co-simulation framework predict more than ˜100x improvement in computation energy as compared to state of the art CMOS design, for optimal spin-device parameters.

  2. Reduction of shunt current in buffer-free IrMn based spin-valve structures

    Science.gov (United States)

    Kocaman, B.; Akdoğan, N.

    2018-06-01

    The presence of thick buffer layers in magnetic sensor devices decreases sensor sensitivity due to shunt currents. With this motivation, we produced IrMn-based spin-valve multilayers without using buffer layer. We also studied the effects of post-annealing and IrMn thickness on exchange bias field (HEB) and blocking temperature (TB) of the system. Magnetization measurements indicate that both HEB and TB values are significantly enhanced with post-annealing of IrMn layer. In addition, we report that IrMn thickness of the system strongly influences the magnetization and transport characteristics of the spin-valve structures. We found that the minimum thickness of IrMn layer is 6 nm in order to achieve the lowest shunt current and high blocking temperature (>300 K). We also investigated the training of exchange bias to check the long-term durability of IrMn-based spin-valve structures for device applications.

  3. Spin-polarized light-emitting diodes based on organic bipolar spin valves

    Science.gov (United States)

    Vardeny, Zeev Valentine; Nguyen, Tho Duc; Ehrenfreund, Eitan Avraham

    2017-10-25

    Spin-polarized organic light-emitting diodes are provided. Such spin-polarized organic light-emitting diodes incorporate ferromagnetic electrodes and show considerable spin-valve magneto-electroluminescence and magneto-conductivity responses, with voltage and temperature dependencies that originate from the bipolar spin-polarized space charge limited current.

  4. Spin valve sensor for biomolecular identification: Design, fabrication, and characterization

    Science.gov (United States)

    Li, Guanxiong

    Biomolecular identification, e.g., DNA recognition, has broad applications in biology and medicine such as gene expression analysis, disease diagnosis, and DNA fingerprinting. Therefore, we have been developing a magnetic biodetection technology based on giant magnetoresistive spin valve sensors and magnetic nanoparticle (developed for the magnetic nanoparticle detection, assuming the equivalent average field of magnetic nanoparticles and the coherent rotation of spin valve free layer magnetization. Micromagnetic simulations have also been performed for the spin valve sensors. The analytical model and micromagnetic simulations are found consistent with each other and are in good agreement with experiments. The prototype spin valve sensors have been fabricated at both micron and submicron scales. We demonstrated the detection of a single 2.8-mum magnetic microbead by micron-sized spin valve sensors. Based on polymer-mediated self-assembly and fine lithography, a bilayer lift-off process was developed to deposit magnetic nanoparticles onto the sensor surface in a controlled manner. With the lift-off deposition method, we have successfully demonstrated the room temperature detection of monodisperse 16-nm Fe3O 4 nanoparticles in a quantity from a few tens to several hundreds by submicron spin valve sensors, proving the feasibility of the nanoparticle detection. As desired for quantitative biodetection, a fairly linear dependence of sensor signal on the number of nanoparticles has been confirmed. The initial detection of DNA hybridization events labeled by magnetic nanoparticles further proved the magnetic biodetection concept.

  5. Spin filter effect of hBN/Co detector electrodes in a 3D topological insulator spin valve

    Science.gov (United States)

    Vaklinova, Kristina; Polyudov, Katharina; Burghard, Marko; Kern, Klaus

    2018-03-01

    Topological insulators emerge as promising components of spintronic devices, in particular for applications where all-electrical spin control is essential. While the capability of these materials to generate spin-polarized currents is well established, only very little is known about the spin injection/extraction into/out of them. Here, we explore the switching behavior of lateral spin valves comprising the 3D topological insulator Bi2Te2Se as channel, which is separated from ferromagnetic Cobalt detector contacts by an ultrathin hexagonal boron nitride (hBN) tunnel barrier. The corresponding contact resistance displays a notable variation, which is correlated with a change of the switching characteristics of the spin valve. For contact resistances below ~5 kΩ, the hysteresis in the switching curve reverses upon reversing the applied current, as expected for spin-polarized currents carried by the helical surface states. By contrast, for higher contact resistances an opposite polarity of the hysteresis loop is observed, which is independent of the current direction, a behavior signifying negative spin detection efficiency of the multilayer hBN/Co contacts combined with bias-induced spin signal inversion. Our findings suggest the possibility to tune the spin exchange across the interface between a ferromagnetic metal and a topological insulator through the number of intervening hBN layers.

  6. Spin transfer torque in antiferromagnetic spin valves: From clean to disordered regimes

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed

    2014-05-28

    Current-driven spin torques in metallic spin valves composed of antiferromagnets are theoretically studied using the nonequilibrium Green\\'s function method implemented on a tight-binding model. We focus our attention on G-type and L-type antiferromagnets in both clean and disordered regimes. In such structures, spin torques can either rotate the magnetic order parameter coherently (coherent torque) or compete with the internal antiferromagnetic exchange (exchange torque). We show that, depending on the symmetry of the spin valve, the coherent and exchange torques can either be in the plane, ∝n×(q×n) or out of the plane ∝n×q, where q and n are the directions of the order parameter of the polarizer and the free antiferromagnetic layers, respectively. Although disorder conserves the symmetry of the torques, it strongly reduces the torque magnitude, pointing out the need for momentum conservation to ensure strong spin torque in antiferromagnetic spin valves.

  7. Spin transfer torque in antiferromagnetic spin valves: From clean to disordered regimes

    KAUST Repository

    Saidaoui, Hamed Ben Mohamed; Manchon, Aurelien; Waintal, Xavier

    2014-01-01

    Current-driven spin torques in metallic spin valves composed of antiferromagnets are theoretically studied using the nonequilibrium Green's function method implemented on a tight-binding model. We focus our attention on G-type and L-type antiferromagnets in both clean and disordered regimes. In such structures, spin torques can either rotate the magnetic order parameter coherently (coherent torque) or compete with the internal antiferromagnetic exchange (exchange torque). We show that, depending on the symmetry of the spin valve, the coherent and exchange torques can either be in the plane, ∝n×(q×n) or out of the plane ∝n×q, where q and n are the directions of the order parameter of the polarizer and the free antiferromagnetic layers, respectively. Although disorder conserves the symmetry of the torques, it strongly reduces the torque magnitude, pointing out the need for momentum conservation to ensure strong spin torque in antiferromagnetic spin valves.

  8. Valve packing leakage monitoring device

    International Nuclear Information System (INIS)

    Ezekoye, L.I.

    1985-01-01

    A device for monitoring leakage of fluid across a seal in a component connected to a pressurized fluid system including a housing having a chamber with an inlet for receiving fluid leaking across the seal and an outlet. A positioning means is connected to an orifice plug so as to move the plug for permitting the fluid to be discharged through the orifice at the same rate at which it enters the first chamber and means for detecting the movement of the plug is provided to produce and output signal corresponding to the distance moved by the plug and thereby indicate flow rate. The positioning means compromise a piston attached to the plug by a hollow tube and springs, which at low flow rates locate the piston. When flow increases sufficiently pressure increases and urges the piston upwards. A magnetic portion of tube actuates a succession of proximity switches to indicate flow rate. (author)

  9. Spin valve effect in single-atom contacts

    International Nuclear Information System (INIS)

    Ziegler, M; Neel, N; Berndt, R; Lazo, C; Ferriani, P; Heinze, S; Kroeger, J

    2011-01-01

    Magnetic single-atom contacts have been controllably fabricated with a scanning tunnelling microscope. A voltage-dependent spin valve effect with conductance variations of ∼40% is reproducibly observed from contacts comprising a Cr-covered tip and Co and Cr atoms on ferromagnetic nanoscale islands on W(110) with opposite magnetization. The spin-dependent conductances are interpreted from first-principles calculations in terms of the orbital character of the relevant electronic states of the junction.

  10. High frequency spin torque oscillators with composite free layer spin valve

    International Nuclear Information System (INIS)

    Natarajan, Kanimozhi; Arumugam, Brinda; Rajamani, Amuda

    2016-01-01

    We report the oscillations of magnetic spin components in a composite free layer spin valve. The associated Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation is studied by stereographically projecting the spin on to a complex plane and the spin components were found. A fourth order Runge–Kutta numerical integration on LLGS equation also confirms the similar trajectories of the spin components. This study establishes the possibility of a Spin Torque Oscillator in a composite free layer spin valve, where the exchange coupling is ferromagnetic in nature. In-plane and out-of-plane precessional modes of magnetization oscillations were found in zero applied magnetic field and the frequencies of the oscillations were calculated from Fast Fourier Transform of the components of magnetization. Behavior of Power Spectral Density for a range of current density is studied. Finally our analysis shows the occurrence of highest frequency 150 GHz, which is in the second harmonics for the specific choice of system parameters.

  11. High frequency spin torque oscillators with composite free layer spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Natarajan, Kanimozhi; Arumugam, Brinda; Rajamani, Amuda

    2016-07-15

    We report the oscillations of magnetic spin components in a composite free layer spin valve. The associated Landau–Lifshitz–Gilbert–Slonczewski (LLGS) equation is studied by stereographically projecting the spin on to a complex plane and the spin components were found. A fourth order Runge–Kutta numerical integration on LLGS equation also confirms the similar trajectories of the spin components. This study establishes the possibility of a Spin Torque Oscillator in a composite free layer spin valve, where the exchange coupling is ferromagnetic in nature. In-plane and out-of-plane precessional modes of magnetization oscillations were found in zero applied magnetic field and the frequencies of the oscillations were calculated from Fast Fourier Transform of the components of magnetization. Behavior of Power Spectral Density for a range of current density is studied. Finally our analysis shows the occurrence of highest frequency 150 GHz, which is in the second harmonics for the specific choice of system parameters.

  12. Role of the magnetic anisotropy in organic spin valves

    Directory of Open Access Journals (Sweden)

    V. Kalappattil

    2017-09-01

    Full Text Available Magnetic anisotropy plays an important role in determining the magnetic functionality of thin film based electronic devices. We present here, the first systematic study of the correlation between magnetoresistance (MR response in organic spin valves (OSVs and magnetic anisotropy of the bottom ferromagnetic electrode over a wide temperature range (10 K–350 K. The magnetic anisotropy of a La0.67Sr0.33MnO3 (LSMO film epitaxially grown on a SrTiO3 (STO substrate was manipulated by reducing film thickness from 200 nm to 20 nm. Substrate-induced compressive strain was shown to drastically increase the bulk in-plane magnetic anisotropy when the LSMO became thinner. In contrast, the MR response of LSMO/OSC/Co OSVs for many organic semiconductors (OSCs does not depend on either the in-plane magnetic anisotropy of the LSMO electrodes or their bulk magnetization. All the studied OSV devices show a similar temperature dependence of MR, indicating a similar temperature-dependent spinterface effect irrespective of LSMO thickness, resulting from the orbital hybridization of carriers at the OSC/LSMO interface.

  13. Thermal stability of low dose Ga+ ion irradiated spin valves

    International Nuclear Information System (INIS)

    Qi Xianjin; Wang Yingang; Zhou Guanghong; Li Ziquan

    2009-01-01

    The thermal stability of low dose Ga + ion irradiated spin valves has been investigated and compared with that of the as-prepared ones. The dependences of exchange field, measured using vibrating sample magnetometer at room temperature, on magnetic field sweep rate and time spent at negative saturation of the pinned ferromagnetic layer, and training effect were explored. The training effect is observed on both the irradiated spin valves and the as-prepared ones. The magnetic field sweep rate dependence of the exchange bias field of the irradiated spin valves is nearly the same as that of the as-prepared ones. For the as-prepared structure thermal activation has been observed, which showed that holding the irradiated structure at negative saturation of the pinned ferromagnetic layer for up to 28 hours results in no change in the exchange field. The results indicate that the thermal stability of the ion irradiated spin valves is the same as or even better than the as-prepared ones.

  14. Large Magnetoresistance at High Bias Voltage in Double-layer Organic Spin Valves

    Science.gov (United States)

    Subedi, R. C.; Liang, S. H.; Geng, R.; Zhang, Q. T.; Lou, L.; Wang, J.; Han, X. F.; Nguyen, T. D.

    We report studies of magnetoresistance (MR) in double-layer organic spin valves (DOSV) using tris (8-hydroxyquinolinato) aluminum (Alq3) spacers. The device exhibits three distinct resistance levels depending on the relative magnetizations of the ferromagnetic electrodes. We observed a much weaker bias voltage dependence of MR in the device compared to that in the conventional organic spin valve (OSV). The MR magnitude reduces by the factor of two at 0.7 V bias voltage in the DOSV compared to 0.02 V in the conventional OSV. Remarkably, the MR magnitude reaches 0.3% at 6 V bias in the DOSVs, the largest MR response ever reported in OSVs at this bias. Our finding may have a significant impact on achieving high efficient bipolar OSVs strictly performed at high voltages. University of Georgia start-up fund, Ministry of Education, Singapore, National Natural Science Foundation of China.

  15. Spin-resolved electron waiting times in a quantum-dot spin valve

    Science.gov (United States)

    Tang, Gaomin; Xu, Fuming; Mi, Shuo; Wang, Jian

    2018-04-01

    We study the electronic waiting-time distributions (WTDs) in a noninteracting quantum-dot spin valve by varying spin polarization and the noncollinear angle between the magnetizations of the leads using the scattering matrix approach. Since the quantum-dot spin valve involves two channels (spin up and down) in both the incoming and outgoing channels, we study three different kinds of WTDs, which are two-channel WTD, spin-resolved single-channel WTD, and cross-channel WTD. We analyze the behaviors of WTDs in short times, correlated with the current behaviors for different spin polarizations and noncollinear angles. Cross-channel WTD reflects the correlation between two spin channels and can be used to characterize the spin-transfer torque process. We study the influence of the earlier detection on the subsequent detection from the perspective of cross-channel WTD, and define the influence degree quantity as the cumulative absolute difference between cross-channel WTDs and first-passage time distributions to quantitatively characterize the spin-flip process. We observe that influence degree versus spin-transfer torque for different noncollinear angles as well as different polarizations collapse into a single curve showing universal behaviors. This demonstrates that cross-channel WTDs can be a pathway to characterize spin correlation in spintronics system.

  16. Diagnostic for two-mode variable valve activation device

    Science.gov (United States)

    Fedewa, Andrew M

    2014-01-07

    A method is provided for diagnosing a multi-mode valve train device which selectively provides high lift and low lift to a combustion valve of an internal combustion engine having a camshaft phaser actuated by an electric motor. The method includes applying a variable electric current to the electric motor to achieve a desired camshaft phaser operational mode and commanding the multi-mode valve train device to a desired valve train device operational mode selected from a high lift mode and a low lift mode. The method also includes monitoring the variable electric current and calculating a first characteristic of the parameter. The method also includes comparing the calculated first characteristic against a predetermined value of the first characteristic measured when the multi-mode valve train device is known to be in the desired valve train device operational mode.

  17. Giant magneto-spin-Seebeck effect and magnon transfer torques in insulating spin valves

    Science.gov (United States)

    Cheng, Yihong; Chen, Kai; Zhang, Shufeng

    2018-01-01

    We theoretically study magnon transport in an insulating spin valve (ISV) made of an antiferromagnetic insulator sandwiched between two ferromagnetic insulator (FI) layers. In the conventional metal-based spin valve, the electron spins propagate between two metallic ferromagnetic layers, giving rise to giant magnetoresistance and spin transfer torque. Here, the incoherent magnons in the ISV serve as angular momentum carriers and are responsible for the angular momentum transport between two FI layers across the antiferromagnetic spacer. We predict two transport phenomena in the presence of the temperature gradient: a giant magneto-spin-Seebeck effect in which the output voltage signal is controlled by the relative orientation of the two FI layers and magnon transfer torque that can be used for switching the magnetization of the FI layers with a temperature gradient of the order of 0.1 Kelvin per nanometer.

  18. Spin relaxation through Kondo scattering in Cu/Py lateral spin valves

    Science.gov (United States)

    Batley, J. T.; Rosaond, M. C.; Ali, M.; Linfield, E. H.; Burnell, G.; Hickey, B. J.

    Within non-magnetic metals it is reasonable to expect the Elliot-Yafet mechanism to govern spin-relaxation and thus the temperature dependence of the spin diffusion length might be inversely proportional to resistivity. However, in lateral spin valves, measurements have found that at low temperatures the spin diffusion length unexpectedly decreases. We have fabricated lateral spin valves from Cu with different concentrations of magnetic impurities. Through temperature dependent charge and spin transport measurements we present clear evidence linking the presence of the Kondo effect within Cu to the suppression of the spin diffusion length below 30 K. We have calculated the spin-relaxation rate and isolated the contribution from magnetic impurities. At very low temperatures electron-electron interactions play a more prominent role in the Kondo effect. Well below the Kondo temperature a strong-coupling regime exists, where the moments become screened and the magnetic dephasing rate is reduced. We also investigate the effect of this low temperature regime (>1 K) on a pure spin current. This work shows the dominant role of Kondo scattering, even in low concentrations of order 1 ppm, within pure spin transport.

  19. Magneto-resistive and spin valve heads fundamentals and applications

    CERN Document Server

    Mallinson, John C

    2002-01-01

    This book is aims to be a comprehensive source on the physics and engineering of magneto-resistive heads. Most of the material is presented in a nonmathematical manner to make it more digestible for researchers, students, developers, and engineers.In addition to revising and updating material available in the first edition, Mallinson has added nine new chapters dealing with various aspects concerning spin valves, the electron spin tunneling effect, the electrostatic discharge effects, read amplifiers, and signal-to-noise ratios, making this a completely up-to-date reference.Th

  20. Four-state ferroelectric spin-valve

    Czech Academy of Sciences Publication Activity Database

    Quindeau, A.; Fina, I.; Martí, Xavier; Apachitei, G.; Ferrer, P.; Nicklin, C.; Pippel, E.; Hesse, D.; Alexe, M.

    2015-01-01

    Roč. 5, May (2015), 09749 ISSN 2045-2322 Institutional support: RVO:68378271 Keywords : electronic and spintronic devices * ferroelectrics and multiferroics Subject RIV: BE - Theoretical Physics Impact factor: 5.228, year: 2015

  1. Superconducting spin valve effect in Fe/In based heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Leksin, Pavel; Schumann, Joachim; Kataev, Vladislav; Schmidt, Oliver; Buechner, Bernd [Leibniz Institute for Solid State and Materials Research IFW Dresden (Germany); Garifyanov, Nadir; Garifullin, Ilgiz [Zavoisky Physical-Technical Institute, Kazan Scientific Center, Russian Academy of Sciences (Russian Federation)

    2015-07-01

    We report on magnetic and superconducting properties of the spin-valve multilayer system CoOx/Fe1/Cu/Fe2/In. The Superconducting Spin Valve Effect (SSVE) assumes the T{sub c} difference between parallel (P) and antiparallel (AP) orientations of the Fe1 and Fe2 layers' magnetizations. The SSVE value oscillates and changes its sign when the Fe2 layer thickness d{sub Fe2} is varied from 0 to 5 nm. The SSVE value is positive, as expected, in the range 0.4 nm ≤ d{sub Fe2} ≤ 0.8 nm. For a rather broad range of thicknesses 1 nm ≤ d{sub Fe2} ≤ 2.6 nm the SSVE has negative sign assuming the inverse SSVE. Moreover, the magnitude of the inverse effect is larger than that of the positive direct effect. We attribute these oscillations to a quantum interference of the cooper pair wave functions in the magnetic part of the system. For most of the spin-valve samples from this set we experimentally realized the full switching between normal and superconducting states due to direct and inverse SSVE. The analysis of the experimental data has enabled the determination of all microscopic parameters of the studied system.

  2. On the temperature dependence of spin pumping in ferromagnet–topological insulator–ferromagnet spin valves

    Directory of Open Access Journals (Sweden)

    A.A. Baker

    Full Text Available Topological insulators (TIs have a large potential for spintronic devices owing to their spin-polarized, counter-propagating surface states. Recently, we have investigated spin pumping in a ferromagnet–TI–ferromagnet structure at room temperature. Here, we present the temperature-dependent measurement of spin pumping down to 10 K, which shows no variation with temperature. Keywords: Topological insulator, Spin pumping, Spintronics, Ferromagnetic resonance

  3. Vortex Flipping in Superconductor-Ferromagnet Spin Valve Structures

    Science.gov (United States)

    Patino, Edgar J.; Aprili, Marco; Blamire, Mark; Maeno, Yoshiteru

    2014-03-01

    We report in plane magnetization measurements on Ni/Nb/Ni/CoO and Co/Nb/Co/CoO spin valve structures with one of the ferromagnetic layers pinned by an antiferromagnetic layer. In samples with Ni, below the superconducting transition Tc, our results show strong evidence of vortex flipping driven by the ferromagnets magnetization. This is a direct consequence of proximity effect that leads to vortex supercurrents leakage into the ferromagnets. Here the polarized electron spins are subject to vortices magnetic field occasioning vortex flipping. Such novel mechanism has been made possible for the first time by fabrication of the F/S/F/AF multilayered spin valves with a thin-enough S layer to barely confine vortices inside as well as thin-enough F layers to align and control the magnetization within the plane. When Co is used there is no observation of vortex flipping effect. This is attributed to Co shorter coherence length. Interestingly instead a reduction in pinning field of about 400 Oe is observed when the Nb layer is in superconducting state. This effect cannot be explained in terms of vortex fields. In view of these facts any explanation must be directly related to proximity effect and thus a remarkable phenomenon that deserves further investigation. Programa Nacional de Ciencias Basicas COLCIENCIAS (No. 120452128168).

  4. Strain effects on anisotropic magnetoresistance in a nanowire spin valve

    Science.gov (United States)

    Hossain, Md I.; Maksud, M.; Subramanian, A.; Atulasimha, J.; Bandyopadhyay, S.

    2016-11-01

    The longitudinal magnetoresistance of a copper nanowire contacted by two cobalt contacts shows broad spin-valve peaks at room temperature. However, when the contacts are slightly heated, the peaks change into troughs which are signature of anisotropic magnetoresistance (AMR). Under heating, the differential thermal expansion of the contacts and the substrate generates a small strain in the cobalt contacts which enhances the AMR effect sufficiently to change the peak into a trough. This shows the extreme sensitivity of AMR to strain. The change in the AMR resistivity coefficient due to strain is estimated to be a few m Ω -m/microstrain.

  5. Transcatheter Mitral Valve Devices - Functional Mechanical Designs.

    Science.gov (United States)

    Kliger, Chad

    2014-03-01

    Mitral regurgitation is a complex disorder involving a multitude of components of the mitral apparatus. With the desire for less invasive treatment approaches, transcatheter mitral valve therapies (TMVT) are directed at these components and available at varying stages of development. Therapeutic advancements and the potential to combine technologies may further improve their efficacy and safety. Transcatheter mitral valve replacement, while preserving the mitral apparatus, may emerge as an alternative or even a more suitable treatment option. In addition, early data on transcatheter mitral valve-in-valve and valve-in-ring implantation are encouraging and this approach may be an alternative to reoperation in the high-risk patient. This review details the expanding functional mechanical designs of current active TMVT.

  6. Magnetic scanning gate microscopy of CoFeB lateral spin valve

    Directory of Open Access Journals (Sweden)

    Héctor Corte-León

    2017-05-01

    Full Text Available Devices comprised of CoFeB nanostructures with perpendicular magnetic anisotropy and non-magnetic Ta channel were operated in thermal lateral spin valve (LSV mode and studied by magnetotransport measurements and magnetic scanning gate microscopy (SGM. Due to the short spin diffusion length of Ta, the spin diffusion signal was suppressed, allowing the study of the contribution from the anomalous Nernst (ANE and anomalous Hall effects (AHE. The magnetotransport measurements identified the switching fields of the CoFeB nanostructures and demonstrated a combination of AHE and ANE when the devices were operated in thermally-driven spin-injection mode. Modified scanning probe microscopy probes were fabricated by placing a NdFeB magnetic bead (MB on the apex of a commercial Si probe. The dipole magnetic field distribution around the MB was characterized by using differential phase contrast technique and direct measurement of the switching field induced by the bead in the CoFeB nanodevices. Using SGM we demonstrate the influence of localized magnetic field on the CoFeB nanostructures near the non-magnetic channel. This approach provides a promising route towards the study of thermal and spin diffusion effects using local magnetic fields.

  7. Magnetic scanning gate microscopy of CoFeB lateral spin valve

    Science.gov (United States)

    Corte-León, Héctor; Scarioni, Alexander Fernandez; Mansell, Rhodri; Krzysteczko, Patryk; Cox, David; McGrouther, Damien; McVitie, Stephen; Cowburn, Russell; Schumacher, Hans W.; Antonov, Vladimir; Kazakova, Olga

    2017-05-01

    Devices comprised of CoFeB nanostructures with perpendicular magnetic anisotropy and non-magnetic Ta channel were operated in thermal lateral spin valve (LSV) mode and studied by magnetotransport measurements and magnetic scanning gate microscopy (SGM). Due to the short spin diffusion length of Ta, the spin diffusion signal was suppressed, allowing the study of the contribution from the anomalous Nernst (ANE) and anomalous Hall effects (AHE). The magnetotransport measurements identified the switching fields of the CoFeB nanostructures and demonstrated a combination of AHE and ANE when the devices were operated in thermally-driven spin-injection mode. Modified scanning probe microscopy probes were fabricated by placing a NdFeB magnetic bead (MB) on the apex of a commercial Si probe. The dipole magnetic field distribution around the MB was characterized by using differential phase contrast technique and direct measurement of the switching field induced by the bead in the CoFeB nanodevices. Using SGM we demonstrate the influence of localized magnetic field on the CoFeB nanostructures near the non-magnetic channel. This approach provides a promising route towards the study of thermal and spin diffusion effects using local magnetic fields.

  8. Microwave spectroscopy and electronic transport properties of ferromagnetic Josephson junctions and superconducting spin-valves

    Energy Technology Data Exchange (ETDEWEB)

    Thalmann, Marcel; Rudolf, Marcel; Pietsch, Torsten [Zukunftskolleg and Department of Physics, University of Konstanz, Universitaetsstrasse 10, 78464 Konstanz (Germany)

    2016-07-01

    Hybrid superconducting nanostructures recently attracted tremendous interest, due to their great potential in dissipation-less spin-electronics with unprecedented switching rates. The practical realisation of such devices, however, requires a complete understanding of the transfer and dynamics of spin- and charge currents between superconducting (S) and ferromagnetic (F) circuit elements, as well as the coupling between spin- and charge degrees of freedom in these systems. We investigate novel transport phenomena in superconductor-ferromagnet hybrid nanostructures under non-equilibrium conditions. Microwave spectroscopy is used to elucidate fundamental questions related to the complex interplay of competing order parameters and the question of relaxation mechanisms of non-equilibrium distributions with respect to spin, charge and energy. Recent experiments on two complimentary device structures are discussed: (I) in diffusive S/F/S Josephson junctions with non-sinusoidal current-phase relationship and (II) local and non-local transport measurements and microwave spectroscopy in F/S/F lateral spin-valves.

  9. Transcatheter Aortic Valve Replacement With Early- and New-Generation Devices in Bicuspid Aortic Valve Stenosis

    DEFF Research Database (Denmark)

    Yoon, Sung Han; Lefèvre, Thierry; Ahn, Jung Ming

    2016-01-01

    Background Few studies have evaluated the clinical outcomes of transcatheter aortic valve replacement (TAVR) in patients with bicuspid aortic valve stenosis (AS). Particularly, limited data exist comparing the results of TAVR with new-generation devices versus early-generation devices.  Objectives...... This study sought to evaluate the clinical outcomes of TAVR for bicuspid AS with early- and new-generation devices.  Methods The Bicuspid TAVR Registry is an international multicenter study enrolling consecutive patients with bicuspid AS undergoing TAVR between April 2005 and May 2015.  Results Of 301...... patients, 199 patients (71.1%) were treated with early-generation devices (Sapien XT [Edwards Lifesciences Corporation, Irvine, California]: n = 87; CoreValve [Medtronic, Minneapolis, Minnesota]: n = 112) and 102 with new-generation devices (Sapien 3 [Edwards Lifesciences Corporation]: n = 91; Lotus...

  10. Photoemission microscopy study of picosecond magnetodynamics in spin-valve-type thin film elements

    International Nuclear Information System (INIS)

    Schneider, C.M.; Kaiser, A.; Wiemann, C.; Tieg, C.; Cramm, S.

    2010-01-01

    Exploring ultimate time scales of magnetic switching processes is an important issue in spin electronics. In spin valves or magnetic tunnelling junctions magnetic anisotropies and coupling phenomena alter the magnetodynamic response of the entire system. Understanding the role of these interactions is a key to the design of optimized devices. We have employed time-resolved X-ray photoemission microscopy to address the magnetodynamics in spin-valve-type model systems in the ns- and ps-regime. In Co/Cr/Fe(0 0 1) single crystal elements we find a strong influence of the magnetocrystalline anisotropy, which tends to suppress rotation processes. In addition, we observe a dynamic 'decoupling' of the layers. In low-anisotropy FeNi/Cr/FeCo trilayers, the interlayer coupling character determines the dynamic response. Particularly, rotational processes in the FeNi and FeCo layers are temporarily shifted to each other, which can be related to different coercivities of the individual layers. By contrast, the domain wall motion in both layers closely agrees, caused by an enhanced coupling due to the domain wall stray fields. Our examples demonstrate that the detailed magnetodynamics in coupled magnetic layers is quite complex and depends strongly on the timescale under consideration.

  11. Pseudo spin-valve behavior in oxide ferromagnet/superconductor/ferromagnet trilayers

    International Nuclear Information System (INIS)

    Pang, B.S.H.; Bell, C.; Tomov, R.I.; Durrell, J.H.; Blamire, M.G.

    2005-01-01

    La 0.7 Ca 0.3 MnO 3 /YBa 2 Cu 3 O 7-δ /La 0.67 Sr 0.33 MnO 3 heterostructural devices with double coercivity have been fabricated. The superconducting critical current (I c ) and critical temperature in both parallel (P) and antiparallel (AP) magnetic configurations remained unchanged within our measurement limits. This observation is contrary to results obtained elsewhere using similar metallic systems. A pseudo spin-valve magnetoresistive (MR) characteristic was observed at bias current (I bias )∼I c at temperatures below the onset of superconductivity. The effect increased with decreasing temperature and I bias and can be explained using the assumption of the electron spin-charge separation

  12. A molecular spin-photovoltaic device.

    Science.gov (United States)

    Sun, Xiangnan; Vélez, Saül; Atxabal, Ainhoa; Bedoya-Pinto, Amilcar; Parui, Subir; Zhu, Xiangwei; Llopis, Roger; Casanova, Fèlix; Hueso, Luis E

    2017-08-18

    We fabricated a C 60 fullerene-based molecular spin-photovoltaic device that integrates a photovoltaic response with the spin transport across the molecular layer. The photovoltaic response can be modified under the application of a small magnetic field, with a magnetophotovoltage of up to 5% at room temperature. Device functionalities include a magnetic current inverter and the presence of diverging magnetocurrent at certain illumination levels that could be useful for sensing. Completely spin-polarized currents can be created by balancing the external partially spin-polarized injection with the photogenerated carriers. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  13. Influence of mechanical strain on magnetic characteristics of spin valves

    International Nuclear Information System (INIS)

    Ac, V; Anwarzai, B; Luby, S; Majkova, E

    2008-01-01

    Giant magnetoresistance (GMR) of Co and Fe-Co based e-beam evaporated spin valves with Cu and Au spacers was studied. The effect of strain on samples, which is detrimental in standard GMR sensors, was measured in a bending configuration. The different dependences of coercivity H c and magnetic field H ip in the point of inflection of MR loops vs. strain were found. For sample with Co/Au/Co core, H c , H ip increase with increasing compressive stress, whereas for sample with FeCo/Cu/Co core they increase with tensile stress. The highest relative change of MR ratio vs. bending in the strain interval ± 300 x 10 -6 is 1-2 % of the basic magnetoresistance and, practically, it does not influence the SV output

  14. Effective suppression of thermoelectric voltage in nonlocal spin-valve measurement

    Science.gov (United States)

    Ariki, Taisei; Nomura, Tatsuya; Ohnishi, Kohei; Kimura, Takashi

    2017-06-01

    We demonstrate that the background signal in the nonlocal spin-valve measurement can be sufficiently suppressed by optimizing the electrode design of the lateral spin valve. A relatively long length scale of heat propagation produces spin-independent thermoelectric signals under the combination of the Peltier and Seebeck effects. These unfavorable signals can be reduced by mixing the Peltier effects in two transparent ferromagnetic/nonmagnetic junctions. Proper understanding of the contribution from the heat current in no spin-current area is a key for effective reduction of the spin-independent background signal.

  15. Superconducting spin valves controlled by spiral re-orientation in B20-family magnets

    Science.gov (United States)

    Pugach, N. G.; Safonchik, M.; Champel, T.; Zhitomirsky, M. E.; Lähderanta, E.; Eschrig, M.; Lacroix, C.

    2017-10-01

    We propose a superconducting spin-triplet valve, which consists of a superconductor and an itinerant magnetic material, with the magnet showing an intrinsic non-collinear order characterized by a wave vector that may be aligned in a few equivalent preferred directions under the control of a weak external magnetic field. Re-orienting the spiral direction allows one to controllably modify long-range spin-triplet superconducting correlations, leading to spin-valve switching behavior. Our results indicate that the spin-valve effect may be noticeable. This bilayer may be used as a magnetic memory element for cryogenic nanoelectronics. It has the following advantages in comparison to superconducting spin valves proposed previously: (i) it contains only one magnetic layer, which may be more easily fabricated and controlled; (ii) its ground states are separated by a potential barrier, which solves the "half-select" problem of the addressed switch of memory elements.

  16. Magnetoresistance effect of heat generation in a single-molecular spin-valve

    International Nuclear Information System (INIS)

    Jiang, Feng; Yan, Yonghong; Wang, Shikuan; Yan, Yijing

    2016-01-01

    Based on non-equilibrium Green's functions' theory and small polaron transformation's technology, we study the heat generation by current through a single-molecular spin-valve. Numerical results indicate that the variation of spin polarization degree can change heat generation effectively, the spin-valve effect happens not only in electrical current but also in heat generation when Coulomb repulsion in quantum dot is smaller than phonon frequency and interestingly, when Coulomb repulsion is larger than phonon frequency, the inverse spin-valve effect appears by sweeping gate voltage and is enlarged with bias increasing. The inverse spin-valve effect will induce the unique heat magnetoresistance effect, which can be modulated from heat-resistance to heat-gain by gate voltage easily. - Highlights: • Spin-valve effect of heat generation happens when Coulomb repulsion in quantum dot is less than phonon frequency. • When Coulomb repulsion is larger than phonon frequency, inverse spin-valve effect appears and is enlarged with bias increasing. • The variation of spin polarization degree can change heat generation effectively. • The heat magnetoresistance can be modulated from heat-resistance to heat-gain by gate voltage easily.

  17. Latest-Generation Transcatheter Aortic Valve Replacement Devices and Procedures.

    Science.gov (United States)

    Chamandi, Chekrallah; Puri, Rishi; Rodriguez-Gabella, Tania; Rodés-Cabau, Josep

    2017-09-01

    Transcatheter aortic valve replacement (TAVR) is a well-established treatment for patients with severe symptomatic aortic stenosis who are at high or prohibitive surgical risk. More recently, TAVR has emerged as a valid alternative to surgical aortic valve replacement for treating intermediate-risk patients, and several studies are currently evaluating the role of TAVR in low-risk patients. Transcatheter heart valve (THV) technologies have evolved considerably over time, and important iterations have been implemented in many of the latest-generation devices to (1) reduce the size and improve delivery system properties; (2) improve valve deployment, repositioning, and retrievability; and (3) reduce paravalvular leaks. This article reviews the main characteristics of, and clinical results associated with, the newer-generation THVs while providing an overview of novel TAVR indications. Copyright © 2017 Canadian Cardiovascular Society. Published by Elsevier Inc. All rights reserved.

  18. Contact induced spin relaxation in graphene spin valves with Al2O3 and MgO tunnel barriers

    Directory of Open Access Journals (Sweden)

    Walid Amamou

    2016-03-01

    Full Text Available We investigate spin relaxation in graphene by systematically comparing the roles of spin absorption, other contact-induced effects (e.g., fringe fields, and bulk spin relaxation for graphene spin valves with MgO barriers, Al2O3 barriers, and transparent contacts. We obtain effective spin lifetimes by fitting the Hanle spin precession data with two models that include or exclude the effect of spin absorption. Results indicate that additional contact-induced spin relaxation other than spin absorption dominates the contact effect. For tunneling contacts, we find reasonable agreement between the two models with median discrepancy of ∼20% for MgO and ∼10% for Al2O3.

  19. Isolation valve control device for nuclear power plant

    International Nuclear Information System (INIS)

    Yukinori, Shigeru.

    1990-01-01

    The present invention provides an isolation valve control device for detecting pipeline rupture accidents in a BWR type nuclear power plant at an early stage to close an isolation valve thereby reducing the amout of radioactivity released to the circumstance. That is, isolation valves are disposed in the pipeline for each of the systems in the nuclear power plant and flow ratemeters are disposed to at least two positions in each of the pipelines. If a meaningful difference is shown for the measured values by these flow ratemeters, the isolation valve is closed. In this way, if pipeline rupture such as leak before break (LBB) is caused to a portion of a system pipelines, the measured value from the flow ratemeters at the downstream of the pipeline is lowered. Accordingly, when a meaningful difference is formed between the value of the flow ratematers at the upstream and the downstream, occurrence of pipe rutpture between both of the flow ratemeters can be detected. As a result, the isolation valves of the system can be closed. According to the present invention, it is possible to detect the pipeline rupture at an early stage irrespective of the kind of the systems, diameter of the pipelines and the magnitude of the ruptured area, and the isolation valve can be closed. (I.S.)

  20. MnNi-based spin valve sensors combining high thermal stability, small footprint and pTesla detectivities

    Science.gov (United States)

    Silva, Marília; Leitao, Diana C.; Cardoso, Susana; Freitas, Paulo

    2018-05-01

    Magnetoresistive sensors with high thermal robustness, low noise and high spatial resolution are the answer to a number of challenging applications. Spin valve sensors including MnNi as antiferromagnet layer provide higher exchange bias field and improved thermal stability. In this work, the influence of the buffer layer type (Ta, NiFeCr) and thickness on key sensor parameters (e.g. offset field, Hf) is investigated. A Ta buffer layer promotes a strong (111) texture which leads to a higher value of MR. In contrast, Hf is lower for NiFeCr buffer. Micrometric sensors display thermal noise levels of 1 nT/Hz1/2 and 571 pT/Hz1/2 for a sensor height (h) of 2 and 4 μm, respectively. The temperature dependence of MR and sensitivity is also addressed and compared with MnIr based spin valves. In this case, MR abruptly decreases after heating at 160°C (without magnetic field), contrary to MnNi-based spin valves, where only a 10% MR decrease (relative to the initial value) is seen at 275°C. Finally, to further decrease the noise levels and improve detectivity, MnNi spin-valves are deposited vertically, and connected in parallel and series (in-plane) to create a device with low resistance and high sensitivity. A field detection at thermal level of 346 pT/Hz1/2 is achieved for a device with a total of 300 SVs (4 vertical, 15 in series, 5 in parallel).

  1. Spin transport and spin torque in antiferromagnetic devices

    Science.gov (United States)

    Železný, J.; Wadley, P.; Olejník, K.; Hoffmann, A.; Ohno, H.

    2018-03-01

    Ferromagnets are key materials for sensing and memory applications. In contrast, antiferromagnets, which represent the more common form of magnetically ordered materials, have found less practical application beyond their use for establishing reference magnetic orientations via exchange bias. This might change in the future due to the recent progress in materials research and discoveries of antiferromagnetic spintronic phenomena suitable for device applications. Experimental demonstration of the electrical switching and detection of the Néel order open a route towards memory devices based on antiferromagnets. Apart from the radiation and magnetic-field hardness, memory cells fabricated from antiferromagnets can be inherently multilevel, which could be used for neuromorphic computing. Switching speeds attainable in antiferromagnets far exceed those of ferromagnetic and semiconductor memory technologies. Here, we review the recent progress in electronic spin-transport and spin-torque phenomena in antiferromagnets that are dominantly of the relativistic quantum-mechanical origin. We discuss their utility in pure antiferromagnetic or hybrid ferromagnetic/antiferromagnetic memory devices.

  2. Resistive switching and voltage induced modulation of tunneling magnetoresistance in nanosized perpendicular organic spin valves

    Directory of Open Access Journals (Sweden)

    Robert Göckeritz

    2016-04-01

    Full Text Available Nanoscale multifunctional perpendicular organic spin valves have been fabricated. The devices based on an La0.7Sr0.3MnO3/Alq3/Co trilayer show resistive switching of up to 4-5 orders of magnitude and magnetoresistance as high as -70% the latter even changing sign when voltage pulses are applied. This combination of phenomena is typically observed in multiferroic tunnel junctions where it is attributed to magnetoelectric coupling between a ferromagnet and a ferroelectric material. Modeling indicates that here the switching originates from a modification of the La0.7Sr0.3MnO3 surface. This modification influences the tunneling of charge carriers and thus both the electrical resistance and the tunneling magnetoresistance which occurs at pinholes in the organic layer.

  3. Magnetoresistance in hybrid organic spin valves at the onset of multiple-step tunneling

    NARCIS (Netherlands)

    Schoonus, J.J.H.M.; Lumens, P.G.E.; Wagemans, W.; Kohlhepp, J.T.; Bobbert, P.A.; Swagten, H.J.M.; Koopmans, B.

    2009-01-01

    By combining experiments with simple model calculations, we obtain new insight in spin transport through hybrid, CoFeB/Al2O3(1.5nm)/tris(8- hydroxyquinoline)aluminium (Alq3)/Co spin valves. We have measured the characteristic changes in the I-V behavior as well as the intrinsic loss of

  4. The multi-step tunneling analogue of conductivity mismatch in organic spin valves

    NARCIS (Netherlands)

    Tran, T. Lan Ahn; Le, T.Q.; Sanderink, Johannes G.M.; van der Wiel, Wilfred Gerard; de Jong, Machiel Pieter

    Carbon-based, molecular semiconductors offer several attractive attributes for spintronics, such as exceptionally weak spin-orbit coupling and compatibility with bottom-up nanofabrication. In spite of the promising properties of organic spin valves, however, the physical mechanisms governing

  5. Flexible spin-orbit torque devices

    International Nuclear Information System (INIS)

    Lee, OukJae; You, Long; Jang, Jaewon; Subramanian, Vivek; Salahuddin, Sayeef

    2015-01-01

    We report on state-of-the-art spintronic devices synthesized and fabricated directly on a flexible organic substrate. Large perpendicular magnetic anisotropy was achieved in ultrathin ferromagnetic heterostructures of Pt/Co/MgO sputtered on a non-rigid plastic substrate at room temperature. Subsequently, a full magnetic reversal of the Co was observed by exploiting the spin orbit coupling in Pt that leads to a spin accumulation at the Pt/Co interface when an in-plane current is applied. Quasi-static measurements show the potential for operating these devices at nano-second speeds. Importantly, the behavior of the devices remained unchanged under varying bending conditions (up to a bending radius of ≈ ±20–30 mm). Furthermore, the devices showed robust operation even after application of 10 6 successive pulses, which is likely sufficient for many flexible applications. Thus, this work demonstrates the potential for integrating high performance spintronic devices on flexible substrates, which could lead to many applications ranging from flexible non-volatile magnetic memory to local magnetic resonance imaging

  6. Flexible spin-orbit torque devices

    Energy Technology Data Exchange (ETDEWEB)

    Lee, OukJae; You, Long; Jang, Jaewon; Subramanian, Vivek [Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720 (United States); Salahuddin, Sayeef [Department of Electrical Engineering and Computer Sciences, University of California at Berkeley, Berkeley, California 94720 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2015-12-21

    We report on state-of-the-art spintronic devices synthesized and fabricated directly on a flexible organic substrate. Large perpendicular magnetic anisotropy was achieved in ultrathin ferromagnetic heterostructures of Pt/Co/MgO sputtered on a non-rigid plastic substrate at room temperature. Subsequently, a full magnetic reversal of the Co was observed by exploiting the spin orbit coupling in Pt that leads to a spin accumulation at the Pt/Co interface when an in-plane current is applied. Quasi-static measurements show the potential for operating these devices at nano-second speeds. Importantly, the behavior of the devices remained unchanged under varying bending conditions (up to a bending radius of ≈ ±20–30 mm). Furthermore, the devices showed robust operation even after application of 10{sup 6} successive pulses, which is likely sufficient for many flexible applications. Thus, this work demonstrates the potential for integrating high performance spintronic devices on flexible substrates, which could lead to many applications ranging from flexible non-volatile magnetic memory to local magnetic resonance imaging.

  7. Valley- and spin-switch effects in molybdenum disulfide superconducting spin valve

    Science.gov (United States)

    Majidi, Leyla; Asgari, Reza

    2014-10-01

    We propose a hole-doped molybdenum disulfide (MoS2) superconducting spin valve (F/S/F) hybrid structure in which the Andreev reflection process is suppressed for all incoming waves with a determined range of the chemical potential in ferromagnetic (F) region and the cross-conductance in the right F region depends crucially on the configuration of magnetizations in the two F regions. Using the scattering formalism, we find that the transport is mediated purely by elastic electron cotunneling (CT) process in a parallel configuration and changes to the pure crossed Andreev reflection (CAR) process in the low-energy regime, without fixing of a unique parameter, by reversing the direction of magnetization in the right F region. This suggests both valley- and spin-switch effects between the perfect elastic CT and perfect CAR processes and makes the nonlocal charge current to be fully valley- and spin-polarized inside the right F region where the type of the polarizations can be changed by reversing the magnetization direction in the right F region. We further demonstrate that the presence of the strong spin-orbit interaction λ and an additional topological term (β ) in the Hamiltonian of MoS2 result in an enhancement of the charge conductance of the CT and CAR processes and make them to be present for long lengths of the superconducting region. Besides, we find that the thermal conductance of the structure with a small length of the highly doped superconducting region exhibits linear dependence on the temperature at low temperatures, whereas it enhances exponentially at higher temperatures. In particular, we demonstrate that the thermal conductance versus the strength of the exchange field (h ) in F region displays a maximum value at h <λ , which moves towards larger exchange fields by increasing the temperature.

  8. Electric field-induced magnetoresistance in spin-valve/piezoelectric multiferroic laminates for low-power spintronics

    International Nuclear Information System (INIS)

    Huong Giang, D.T.; Thuc, V.N.; Duc, N.H.

    2012-01-01

    Electric field-induced magnetic anisotropy has been realized in the spin-valve-based {Ni 80 Fe 20 /Cu/Fe 50 Co 50 /IrMn}/piezoelectric multiferroic laminates. In this system, electric-field control of magnetization is accomplished by strain mediated magnetoelectric coupling. Practically, the magnetization in the magnetostrictive FeCo layer of the spin-valve structure rotates under an effective compressive stress caused by the inverse piezoelectric effect in external electrical fields. This phenomenon is evidenced by the magnetization and magnetoresistance changes under the electrical field applied across the piezoelectric layer. The result shows great potential for advanced low-power spintronic devices. - Highlights: ► Investigate electric field-induced magnetic anisotropy in spin-valve/piezoelectric. ► Magnetization, magnetoresistance changes under electric field across piezoelectric. ► Magnetization in magnetostrictive FeCo-layer rotates under a compressive stress. ► This advance shows great implications for low-power electronics and spintronics.

  9. Theory of electrically controlled resonant tunneling spin devices

    Science.gov (United States)

    Ting, David Z. -Y.; Cartoixa, Xavier

    2004-01-01

    We report device concepts that exploit spin-orbit coupling for creating spin polarized current sources using nonmagnetic semiconductor resonant tunneling heterostructures, without external magnetic fields. The resonant interband tunneling psin filter exploits large valence band spin-orbit interaction to provide strong spin selectivity.

  10. Organic Spin-Valves and Beyond: Spin Injection and Transport in Organic Semiconductors and the Effect of Interfacial Engineering.

    Science.gov (United States)

    Jang, Hyuk-Jae; Richter, Curt A

    2017-01-01

    Since the first observation of the spin-valve effect through organic semiconductors, efforts to realize novel spintronic technologies based on organic semiconductors have been rapidly growing. However, a complete understanding of spin-polarized carrier injection and transport in organic semiconductors is still lacking and under debate. For example, there is still no clear understanding of major spin-flip mechanisms in organic semiconductors and the role of hybrid metal-organic interfaces in spin injection. Recent findings suggest that organic single crystals can provide spin-transport media with much less structural disorder relative to organic thin films, thus reducing momentum scattering. Additionally, modification of the band energetics, morphology, and even spin magnetic moment at the metal-organic interface by interface engineering can greatly impact the efficiency of spin-polarized carrier injection. Here, progress on efficient spin-polarized carrier injection into organic semiconductors from ferromagnetic metals by using various interface engineering techniques is presented, such as inserting a metallic interlayer, a molecular self-assembled monolayer (SAM), and a ballistic carrier emitter. In addition, efforts to realize long spin transport in single-crystalline organic semiconductors are discussed. The focus here is on understanding and maximizing spin-polarized carrier injection and transport in organic semiconductors and insight is provided for the realization of emerging organic spintronics technologies. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Magnetostrictive GMR spin valves with composite FeGa/FeCo free layers

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Luping [Key Laboratory of Magnetic Materials and Devices & Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China); Zhan, Qingfeng, E-mail: zhanqf@nimte.ac.cn, E-mail: runweili@nimte.ac.cn; Yang, Huali; Li, Huihui; Zhang, Shuanglan; Liu, Yiwei; Wang, Baomin; Li, Run-Wei, E-mail: zhanqf@nimte.ac.cn, E-mail: runweili@nimte.ac.cn [Key Laboratory of Magnetic Materials and Devices & Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Tan, Xiaohua [Institute of Materials Science, School of Materials Science and Engineering, Shanghai University, Shanghai 200072 (China)

    2016-03-15

    We have fabricated strain-sensitive spin valves on flexible substrates by utilizing the large magnetostrictive FeGa alloy to promote the strain sensitivity and the composite free layer of FeGa/FeCo to avoid the drastic reduction of giant magnetoresistance (GMR) ratio. This kind of spin valve (SV-FeGa/FeCo) displays a MR ratio about 5.9%, which is comparable to that of the conventional spin valve (SV-FeCo) with a single FeCo free layer. Different from the previously reported works on magnetostrictive spin valves, the SV-FeGa/FeCo displays an asymmetric strain dependent GMR behavior. Upon increasing the lateral strain, the MR ratio for the ascending branch decreases more quickly than that for the descending branch, which is ascribed to the formation of a spiraling spin structure around the FeGa/FeCo interface under the combined influences of both magnetic field and mechanical strain. A strain sensitivity of GF = 7.2 was achieved at a magnetic bias field of -30 Oe in flexible SV-FeGa/FeCo, which is significantly larger than that of SV-FeCo.

  12. Magnetostrictive GMR spin valves with composite FeGa/FeCo free layers

    International Nuclear Information System (INIS)

    Liu, Luping; Zhan, Qingfeng; Yang, Huali; Li, Huihui; Zhang, Shuanglan; Liu, Yiwei; Wang, Baomin; Li, Run-Wei; Tan, Xiaohua

    2016-01-01

    We have fabricated strain-sensitive spin valves on flexible substrates by utilizing the large magnetostrictive FeGa alloy to promote the strain sensitivity and the composite free layer of FeGa/FeCo to avoid the drastic reduction of giant magnetoresistance (GMR) ratio. This kind of spin valve (SV-FeGa/FeCo) displays a MR ratio about 5.9%, which is comparable to that of the conventional spin valve (SV-FeCo) with a single FeCo free layer. Different from the previously reported works on magnetostrictive spin valves, the SV-FeGa/FeCo displays an asymmetric strain dependent GMR behavior. Upon increasing the lateral strain, the MR ratio for the ascending branch decreases more quickly than that for the descending branch, which is ascribed to the formation of a spiraling spin structure around the FeGa/FeCo interface under the combined influences of both magnetic field and mechanical strain. A strain sensitivity of GF = 7.2 was achieved at a magnetic bias field of -30 Oe in flexible SV-FeGa/FeCo, which is significantly larger than that of SV-FeCo.

  13. Magnetostrictive GMR spin valves with composite FeGa/FeCo free layers

    Science.gov (United States)

    Liu, Luping; Zhan, Qingfeng; Yang, Huali; Li, Huihui; Zhang, Shuanglan; Liu, Yiwei; Wang, Baomin; Tan, Xiaohua; Li, Run-Wei

    2016-03-01

    We have fabricated strain-sensitive spin valves on flexible substrates by utilizing the large magnetostrictive FeGa alloy to promote the strain sensitivity and the composite free layer of FeGa/FeCo to avoid the drastic reduction of giant magnetoresistance (GMR) ratio. This kind of spin valve (SV-FeGa/FeCo) displays a MR ratio about 5.9%, which is comparable to that of the conventional spin valve (SV-FeCo) with a single FeCo free layer. Different from the previously reported works on magnetostrictive spin valves, the SV-FeGa/FeCo displays an asymmetric strain dependent GMR behavior. Upon increasing the lateral strain, the MR ratio for the ascending branch decreases more quickly than that for the descending branch, which is ascribed to the formation of a spiraling spin structure around the FeGa/FeCo interface under the combined influences of both magnetic field and mechanical strain. A strain sensitivity of GF = 7.2 was achieved at a magnetic bias field of -30 Oe in flexible SV-FeGa/FeCo, which is significantly larger than that of SV-FeCo.

  14. Resistive Switching and Voltage Induced Modulation of Tunneling Magnetoresistance in Nanosized Perpendicular Organic Spin Valves

    Science.gov (United States)

    Schmidt, Georg; Goeckeritz, Robert; Homonnay, Nico; Mueller, Alexander; Fuhrmann, Bodo

    Resistive switching has already been reported in organic spin valves (OSV), however, its origin is still unclear. We have fabricated nanosized OSV based on La0.7Sr0.3MnO3/Alq3/Co. These devices show fully reversible resistive switching of up to five orders of magnitude. The magnetoresistance (MR) is modulated during the switching process from negative (-70%) to positive values (+23%). The results are reminiscent of experiments claiming magnetoelectric coupling in LSMO based tunneling structures using ferroelectric barriers. By analyzing the I/V characteristics of the devices we can show that transport is dominated by tunneling through pinholes. The resistive switching is caused by voltage induced creation and motion of oxygen vacancies at the LSMO surface, however, the resulting tunnel barrier is complemented by a second adjacent barrier in the organic semiconductor. Our model shows that the barrier in the organic material is constant, causing the initial MR while the barrier in the LMSO can be modulated by the voltage resulting in the resistive switching and the modulation of the MR as the coupling to the states in the LSMO changes. A switching caused by LSMO only is also supported by the fact that replacing ALQ3 by H2PC yields almost identical results. Supported by the DFG in the SFB762.

  15. Current-induced magnetic switching of a single molecule magnet on a spin valve

    International Nuclear Information System (INIS)

    Zhang, Xiao; Wang, Zheng-Chuan; Zheng, Qing-Rong; Zhu, Zheng-Gang; Su, Gang

    2015-01-01

    The current-induced magnetic switching of a single-molecule magnet (SMM) attached on the central region of a spin valve is explored, and the condition for the switching current is derived. Electrons flowing through the spin valve will interact with the SMM via the s–d exchange interaction, producing the spin accumulation that satisfies the spin diffusion equation. We further describe the spin motion of the SMM by a Heisenberg-like equation. Based on the linear stability analysis, we obtain the critical current from two coupled equations. The results of the critical current versus the external magnetic field indicate that one can manipulate the magnetic state of the SMM by an external magnetic field. - Highlights: • We theoretically study the current-induced magnetic switching of the SMM. • We describe the spin motion of the SMM by a Heisenberg-like equation. • We describe the spin accumulation by the spin diffusion equation. • We obtain the critical current by the linear stability analysis. • Our approach can be easily extended to other SMMs

  16. Current-induced magnetic switching of a single molecule magnet on a spin valve

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Xiao [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Wang, Zheng-Chuan, E-mail: wangzc@ucas.ac.cn [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Zheng, Qing-Rong [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); Zhu, Zheng-Gang [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China); School of Electronics, Electric and Communication Engineering, University of Chinese Academy of Sciences, Beijing 100049 (China); Su, Gang, E-mail: gsu@ucas.ac.cn [Theoretical Condensed Matter Physics and Computational Materials Physics Laboratory, School of Physics, University of Chinese Academy of Sciences, Beijing 100049 (China)

    2015-04-17

    The current-induced magnetic switching of a single-molecule magnet (SMM) attached on the central region of a spin valve is explored, and the condition for the switching current is derived. Electrons flowing through the spin valve will interact with the SMM via the s–d exchange interaction, producing the spin accumulation that satisfies the spin diffusion equation. We further describe the spin motion of the SMM by a Heisenberg-like equation. Based on the linear stability analysis, we obtain the critical current from two coupled equations. The results of the critical current versus the external magnetic field indicate that one can manipulate the magnetic state of the SMM by an external magnetic field. - Highlights: • We theoretically study the current-induced magnetic switching of the SMM. • We describe the spin motion of the SMM by a Heisenberg-like equation. • We describe the spin accumulation by the spin diffusion equation. • We obtain the critical current by the linear stability analysis. • Our approach can be easily extended to other SMMs.

  17. The magnetoresistive effect induced by stress in spin-valve structures

    International Nuclear Information System (INIS)

    Li-Jie, Qian; Xiao-Yong, Xu; Jing-Guo, Hu

    2009-01-01

    Using a method of free energy minimization, this paper investigates the magnetization properties of a ferromagnetic (FM) monolayer and an FM/antiferromagnetic (AFM) bilayer under a stress field, respectively. It then investigates the magnetoresistance (MR) of the spin-valve structure, which is built by an FM monolayer and an FM/AFM bilayer, and its dependence upon the applied stress field. The results show that under the stress field, the magnetization properties of the FM monolayer is obviously different from that of the FM/AFM bilayer, since the coupled AFM layer can obviously block the magnetization of the FM layer. This phenomenon makes the MR of the spin-valve structure become obvious. In detail, there are two behaviors for the MR of the spin-valve structure dependence upon the stress field distinguished by the coupling (FM coupling or AFM coupling) between the FM layer and the FM/AFM bilayer. Either behavior of the MR of the spin-valve structure depends on the stress field including its value and orientation. Based on these investigations, a perfect mechanical sensor at the nano-scale is suggested to be devised experimentally

  18. The design and investigation of hybrid ferromagnetic/silicon spin electronic devices

    International Nuclear Information System (INIS)

    Pugh, D.I.

    2001-01-01

    The focus of this study concerns the design and investigation of ferromagnetic/silicon hybrid spin electronic devices as part of a wider project to design a novel spin valve transistor. The key issue to obtain a room temperature spin electronic device is the electrical injection of a spin polarised current from a ferromagnetic contact into a semiconductor. Despite many attempts concentrating on GaAs and InAs only small (< 1%) effects have been observed, making it difficult to confirm spin injection. Lateral devices were designed and fabricated using standard device fabrication procedures to produce arrays of Co/Si/So junctions. Subsequent designs aimed to reduce the number of junctions and improve device isolation. Evidence for spin dependent MR of up to 0.56% was observed in Co/p-Si/Co junctions with silicon gaps up to 16 μm in length. The maximum MR was observed when the first Co/Si Schottky barrier was reverse biased forming a high resistance interface. Vertical devices were designed in an attempt to eliminate any alternative current paths by using a well defined, 1 μm thick silicon membrane. Despite attempts to include oxide barriers, no spin dependent MR was observed in these devices. However, a novel vertical silicon based design has been made which should facilitate further advanced studies of spin injection and transport. The spin diffusion length in n-type silicon has been calculated as a function of doping concentration and temperature by considering the spin relaxation mechanisms in the semiconductor. Discussion has been made concerning p-type silicon and comparisons made with GaAs, indicating that n-Si should show longer spin diffusion lengths. The key design criteria for designing room temperature spin electronic devices have been highlighted. These include the use of a high leakage Schottky barrier or tunnel barrier between the ferromagnet and p-Si and a contact to the silicon to enable appropriate biasing to each FM/Si interface. (author)

  19. Spin state determination using Stern-Gerlach device

    International Nuclear Information System (INIS)

    Shirokov, M.I.

    1996-01-01

    The well-known Stern-Gerlach device is proposed here for determination of a particle spin state instead of using it for measurement of spin observables. It is shown that measurement of particle momentum distributions (before and after the action of the device magnetic field) allows one to determine the particle initial spin state in the case of an arbitrary spin value. It is demonstrated that one cannot use for this purpose the usual treatment of the Stern-Gerlach experiment based on the entanglement of spin and spatial states. 11 refs

  20. Spin thermoelectric effects in organic single-molecule devices

    Energy Technology Data Exchange (ETDEWEB)

    Wang, H.L.; Wang, M.X.; Qian, C.; Hong, X.K.; Zhang, D.B.; Liu, Y.S.; Yang, X.F., E-mail: xfyang@cslg.edu.cn

    2017-05-25

    Highlights: • A stronger spin thermoelectric performance in a polyacetylene device is observed. • For the antiferromagnetic (AFM) ordering, a transport gap is opened. Thus the thermoelectric effects are largely enhanced. - Abstract: The spin thermoelectric performance of a polyacetylene chain bridging two zigzag graphene nanoribbons (ZGNRs) is investigated based on first principles method. Two different edge spin arrangements in ZGNRs are considered. For ferromagnetic (FM) ordering, transmission eigenstates with different spin indices distributed below and above Fermi level are observed, leading directly to a strong spin thermoelectric effect in a wide temperature range. With the edge spins arranged in the antiferromagnetic (AFM) ordering, an obvious transport gap appears in the system, which greatly enhances the thermoelectric effects. The presence of a small spin splitting also induces a spin thermoelectric effect greater than the charge thermoelectric effect in certain temperature range. In general, the single-molecule junction exhibits the potential to be used for the design of perfect thermospin devices.

  1. All-spin logic operations: Memory device and reconfigurable computing

    Science.gov (United States)

    Patra, Moumita; Maiti, Santanu K.

    2018-02-01

    Exploiting spin degree of freedom of electron a new proposal is given to characterize spin-based logical operations using a quantum interferometer that can be utilized as a programmable spin logic device (PSLD). The ON and OFF states of both inputs and outputs are described by spin state only, circumventing spin-to-charge conversion at every stage as often used in conventional devices with the inclusion of extra hardware that can eventually diminish the efficiency. All possible logic functions can be engineered from a single device without redesigning the circuit which certainly offers the opportunities of designing new generation spintronic devices. Moreover, we also discuss the utilization of the present model as a memory device and suitable computing operations with proposed experimental setups.

  2. Nanoscale magnetic characterization of tunneling magnetoresistance spin valve head by electron holography.

    Science.gov (United States)

    Park, Hyun Soon; Hirata, Kei; Yanagisawa, Keiichi; Ishida, Yoichi; Matsuda, Tsuyoshi; Shindo, Daisuke; Tonomura, Akira

    2012-12-07

    Nanostructured magnetic materials play an important role in increasing miniaturized devices. For the studies of their magnetic properties and behaviors, nanoscale imaging of magnetic field is indispensible. Here, using electron holography, the magnetization distribution of a TMR spin valve head of commercial design is investigated without and with a magnetic field applied. Characterized is the magnetic flux distribution in complex hetero-nanostructures by averaging the phase images and separating their component magnetic vectors and electric potentials. The magnetic flux densities of the NiFe (shield and 5 nm-free layers) and the CoPt (20 nm-bias layer) are estimated to be 1.0 T and 0.9 T, respectively. The changes in the magnetization distribution of the shield, bias, and free layers are visualized in situ for an applied field of 14 kOe. This study demonstrates the promise of electron holography for characterizing the magnetic properties of hetero-interfaces, nanostructures, and catalysts. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Spin and tunneling dynamics in an asymmetrical double quantum dot with spin-orbit coupling: Selective spin transport device

    Science.gov (United States)

    Singh, Madhav K.; Jha, Pradeep K.; Bhattacherjee, Aranya B.

    2017-09-01

    In this article, we study the spin and tunneling dynamics as a function of magnetic field in a one-dimensional GaAs double quantum dot with both the Dresselhaus and Rashba spin-orbit coupling. In particular, we consider different spatial widths for the spin-up and spin-down electronic states. We find that the spin dynamics is a superposition of slow as well as fast Rabi oscillations. It is found that the Rashba interaction strength as well as the external magnetic field strongly modifies the slow Rabi oscillations which is particularly useful for implementing solid state selective spin transport device.

  4. Electrical detection of spin transport in lateral ferromagnet-semiconductor devices

    Science.gov (United States)

    Lou, Xiaohua

    2007-03-01

    A fully electrical scheme of spin injection, transport, and detection in a single ferromagnet-semiconductor structure has been a long-standing goal in the field of spintronics. In this talk, we report on an experimental demonstration of such a scheme. The devices are fabricated from epitaxial Fe/GaAs (100) heterostructures with highly doped GaAs as a Schottky tunnel barrier. A set of closely spaced Fe contacts on the top of an n-GaAs channel are used as spin injectors and detectors. Reference electrodes are placed at the far ends of the channel, allowing for non-local spin detection [1]. The electro-chemical potential of the detector is sensitive to the relative magnetizations of the injector and detector. In spin-valve measurements, a magnetic field is applied along the Fe easy axis to switch the relative magnetizations of injector and detector from parallel to antiparallel, resulting in a voltage jump that is proportional to the non-equilibrium spin polarization in the channel. A more rigorous test of electrical spin detection is the observation of the Hanle effect, in which an out-of-plane magnetic field is used to modulate and dephase the spin polarization in the channel. The magnitudes of the observed Hanle curves agree with the results of the spin-valve measurements. The dependence of the Hanle curves on temperature and contact separation is studied in detail and is consistent with a drift-diffusion model incorporating spin precession and relaxation. The spin polarization generated by spin injection (reverse bias at the injector) or spin accumulation (forward bias at the injector) is measured using the magneto-optical Kerr effect and is found to be in good agreement with the spin-dependent non-local voltage. Both the transport and optical measurements show a non-linear relationship between the bias voltage at the injector and the spin polarization in the channel. [1] M. Johnson and R. H. Silsbee, Phys. Rev. Lett. 55, 1790 (1985).

  5. Designing innovative retractors and devices to facilitate mitral valve repair surgery

    OpenAIRE

    Okamoto, Kazuma; Yozu, Ryohei

    2015-01-01

    Various devices have been developed to facilitate mitral valve surgery, including those that improve mitral valve exposure and assist surgeons with associated procedures. Choosing appropriate supporting devices when performing minimally invasive mitral valve surgery (MIMVS) through a minithoracotomy with endoscopic assistance is critical. Depending on the surgeon’s preference, trans-thoracic or trans-working-port left atrial retractors can be utilized. Although the trans-thoracic retractors p...

  6. Device for the simultaneous operation of the closing valve of a vessel and the closing valve of a transport container

    International Nuclear Information System (INIS)

    Tellier, Claude; Surriray, Michel.

    1982-01-01

    This device includes mechanisms for unlatching the closing valve of the vessel and securing it to the closing valve of the transport container and other mechanisms for vertically raising the assembly of valves, pivoting it and bringing it into a vertical position in a bulge provided in the bottom of the transport container. For example the first containment is a nuclear reactor vessel and the transport container is used for carrying an item from the vessel to an external area (for instance, a defective pump to the repair area) and for the return transport operation [fr

  7. FY1995 study of high density near-contact magnetic recording using spin valve head; 1995 nendo spin valve head ni yoru chokomitsudo near contact jiki kiroku no kenkyu

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-03-01

    Development of high performance spin valves formed by amorphous magnetic layer and head-medium interface with nano-thickness molecular film for realizing an ultra-high density of 20 Gbit/in{sup 2} using contact recording. The giant magnetoresistance effect was investigated for spin valves using very thin amorphous magnetic layer. In amorphous-CoFeB/Cu/ Co spin valves, the maximum MR ratio of 6% was achieved at the thickness of the amorphous layer of 2 nm. The spin valves with the amorphous layer exhibit very good thermal stability. Design guideline for molecularly thin lubricant was established using newly derived lubrication equation considering lubricant porosity. Novel method for accurately measuring surface force due to molecularly thin lubricant was developed by using Michelson interferometry to detect cantilever displacement, which enabled two-dimensional transient force measurement. (NEDO)

  8. Correlations between atomic structure and giant magnetoresistance ratio in Co2(Fe,Mn)Si spin valves

    International Nuclear Information System (INIS)

    Lari, L; Sizeland, J; Gilks, D; Uddin, G M; Nedelkoski, Z; Hasnip, P J; Lazarov, V K; Yoshida, K; Galindo, P L; Sato, J; Oogane, M; Ando, Y; Hirohata, A

    2014-01-01

    We show that the magnetoresistance of Co 2 Fe x Mn 1−x Si-based spin valves, over 70% at low temperature, is directly related to the structural ordering in the electrodes and at the electrodes/spacer (Co 2 Fe x Mn 1−x Si/Ag) interfaces. Aberration-corrected atomic resolution Z-contrast scanning transmission electron microscopy of device structures reveals that annealing at 350 °C and 500 °C creates partial B2/L2 1 and fully L2 1 ordering of electrodes, respectively. Interface structural studies show that the Ag/Co 2 Fe x Mn 1−x Si interface is more ordered compared to the Co 2 Fe x Mn 1−x Si/Ag interface. The release of interface strain is mediated by misfit dislocations that localize the strain around the dislocation cores, and the effect of this strain is assessed by first principles electronic structure calculations. This study suggests that by improving the atomic ordering and strain at the interfaces, further enhancement of the magnetoresistance of CFMS-based current-perpendicular-to-plane spin valves is possible. (fast track communication)

  9. Magnetoresistance in hybrid organic spin valves at the onset of multiple-step tunneling.

    Science.gov (United States)

    Schoonus, J J H M; Lumens, P G E; Wagemans, W; Kohlhepp, J T; Bobbert, P A; Swagten, H J M; Koopmans, B

    2009-10-02

    By combining experiments with simple model calculations, we obtain new insight in spin transport through hybrid, CoFeB/Al2O3(1.5 nm)/tris(8-hydroxyquinoline)aluminium (Alq3)/Co spin valves. We have measured the characteristic changes in the I-V behavior as well as the intrinsic loss of magnetoresistance at the onset of multiple-step tunneling. In the regime of multiple-step tunneling, under the condition of low hopping rates, spin precession in the presence of hyperfine coupling is conjectured to be the relevant source of spin relaxation. A quantitative analysis leads to the prediction of a symmetric magnetoresistance around zero magnetic field in addition to the hysteretic magnetoresistance curves, which are indeed observed in our experiments.

  10. Magnetotransport in spin-valve systems with amorphous magnetic and superconducting partial layers

    International Nuclear Information System (INIS)

    Steiner, Roland Johannes

    2006-01-01

    The first part of this work deals with the fabrication and characterisation of spin valves with an amorphous FeB layer acting as a weak ferromagnet embedded into the structure. In the second part of this work ferromagnet/superconductor hybrid structures are fabricated and the relevant magnetic field dependent transport phenomena are analyzed. The interlayer of a conventional spin valve was replaced by a superconducting niobium layer. Small applied fields close to the coercivity field of the involved ferromagnets - and thus far below the critical magnetic field of the superconductor - affected the critical temperature of the niobium layer. Measurements of the field dependent resistance and the critical temperature of a FM/SC/FMsystem showed a local maximum in the T c (H)- and the R(H)-curve. (orig.)

  11. Stretchable Spin Valve with Stable Magnetic Field Sensitivity by Ribbon-Patterned Periodic Wrinkles.

    Science.gov (United States)

    Li, Huihui; Zhan, Qingfeng; Liu, Yiwei; Liu, Luping; Yang, Huali; Zuo, Zhenghu; Shang, Tian; Wang, Baomin; Li, Run-Wei

    2016-04-26

    A strain-relief structure by combining the strain-engineered periodic wrinkles and the parallel ribbons was employed to fabricate flexible dual spin valves onto PDMS substrates in a direct sputtering method. The strain-relief structure can accommodate the biaxial strain accompanying with stretching operation (the uniaxial applied tensile strain and the induced transverse compressive strain due to the Poisson effect), thus significantly reducing the influence of the residual strain on the giant magnetoresistance (GMR) performance. The fabricated GMR dual spin-valve sensor exhibits the nearly unchanged MR ratio of 9.9%, magnetic field sensitivity up to 0.69%/Oe, and zero-field resistance in a wide range of stretching strain, making it promising for applications on a conformal shape or a movement part.

  12. Giant tunneling electroresistance effect driven by an electrically controlled spin valve at a complex oxide interface.

    Science.gov (United States)

    Burton, J D; Tsymbal, E Y

    2011-04-15

    A giant tunneling electroresistance effect may be achieved in a ferroelectric tunnel junction by exploiting the magnetoelectric effect at the interface between the ferroelectric barrier and a magnetic La(1-x)Sr(x)MnO3 electrode. Using first-principles density-functional theory we demonstrate that a few magnetic monolayers of La(1-x)Sr(x)MnO3 near the interface act, in response to ferroelectric polarization reversal, as an atomic-scale spin valve by filtering spin-dependent current. This produces more than an order of magnitude change in conductance, and thus constitutes a giant resistive switching effect.

  13. Spin Coherence in Silicon-based Quantum Structures and Devices

    Science.gov (United States)

    2017-08-31

    Using electron spin resonance (ESR) to measure the den- sity of shallow traps, we find that the two sets of devices are nearly identical , indicating...experiments which cannot utilize a clock transition or a field-cancelling decoherence-free subspace. Our approach was to lock the microwave source driving...the electron spins to a strong nuclear spin signal. In our initial experiments we locked to the proton signal in a water cell. However, the noise in

  14. Durability of central aortic valve closure in patients with continuous flow left ventricular assist devices.

    Science.gov (United States)

    McKellar, Stephen H; Deo, Salil; Daly, Richard C; Durham, Lucian A; Joyce, Lyle D; Stulak, John M; Park, Soon J

    2014-01-01

    A competent aortic valve is essential to providing effective left ventricular assist device support. We have adopted a practice of central aortic valve closure by placing a simple coaptation stitch at left ventricular assist device implantation in patients with significant aortic insufficiency. We conducted a follow-up study to evaluate the efficacy and durability of this procedure. The study included patients who had undergone continuous flow left ventricular assist device implantation. The patients were divided into 2 groups, those who did not require any aortic procedure because the valve was competent and those who underwent central aortic valve closure for mild or greater aortic regurgitation. The clinical endpoints were mortality, progression or recurrence of aortic insufficiency, and reoperation for aortic valve pathologic features. Aortic insufficiency was measured qualitatively from mild to severe on a scale of 0 to 5. A total of 123 patients received continuous flow left ventricular assist devices from February 2007 to August 2011. Of those, 18 (15%) underwent central aortic valve closure at left ventricular assist device implantation because of significant aortic insufficiency (1.8 ± 1.4) and 105 who did not (competent aortic valve, 0.15 ± 0.43; P assist device-supported patients, with follow-up extending into 2 years. Although aortic insufficiency progressed over time in those with minimal native valve regurgitation initially, no such progression was noted in those with central aortic valve closure. Additional investigation is needed to evaluate whether prophylactic central aortic valve closure should be performed at left ventricular assist device implantation to avoid problematic aortic regurgitation developing over time, in particular in patients undergoing left ventricular assist device implantation for life-long (destination therapy) support. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights

  15. Left Ventricular Assist Device Implantation with Concomitant Aortic Valve and Ascending Aortic Replacement.

    Science.gov (United States)

    Huenges, Katharina; Panholzer, Bernd; Cremer, Jochen; Haneya, Assad

    2018-01-01

    Left ventricular assist device (LVAD) is nowadays a routine therapy for patients with advanced heart failure. We present the case of a 74-year-old male patient who was admitted to our center with terminal heart failure in dilated cardiomyopathy and ascending aortic aneurysm with aortic valve regurgitation. The LVAD implantation with simultaneous aortic valve and supracoronary ascending aortic replacement was successfully performed.

  16. The Spin Torque Lego - from spin torque nano-devices to advanced computing architectures

    Science.gov (United States)

    Grollier, Julie

    2013-03-01

    Spin transfer torque (STT), predicted in 1996, and first observed around 2000, brought spintronic devices to the realm of active elements. A whole class of new devices, based on the combined effects of STT for writing and Giant Magneto-Resistance or Tunnel Magneto-Resistance for reading has emerged. The second generation of MRAMs, based on spin torque writing : the STT-RAM, is under industrial development and should be out on the market in three years. But spin torque devices are not limited to binary memories. We will rapidly present how the spin torque effect also allows to implement non-linear nano-oscillators, spin-wave emitters, controlled stochastic devices and microwave nano-detectors. What is extremely interesting is that all these functionalities can be obtained using the same materials, the exact same stack, simply by changing the device geometry and its bias conditions. So these different devices can be seen as Lego bricks, each brick with its own functionality. During this talk, I will show how spin torque can be engineered to build new bricks, such as the Spintronic Memristor, an artificial magnetic nano-synapse. I will then give hints on how to assemble these bricks in order to build novel types of computing architectures, with a special focus on neuromorphic circuits. Financial support by the European Research Council Starting Grant NanoBrain (ERC 2010 Stg 259068) is acknowledged.

  17. Anisotropic spin relaxation in graphene

    NARCIS (Netherlands)

    Tombros, N.; Tanabe, S.; Veligura, A.; Jozsa, C.; Popinciuc, M.; Jonkman, H. T.; van Wees, B. J.

    2008-01-01

    Spin relaxation in graphene is investigated in electrical graphene spin valve devices in the nonlocal geometry. Ferromagnetic electrodes with in-plane magnetizations inject spins parallel to the graphene layer. They are subject to Hanle spin precession under a magnetic field B applied perpendicular

  18. Role of the antiferromagnetic pinning layer on spin wave properties in IrMn/NiFe based spin-valves

    Energy Technology Data Exchange (ETDEWEB)

    Gubbiotti, G., E-mail: gubbiotti@fisica.unipg.it; Tacchi, S. [Istituto Officina dei Materiali del CNR (IOM-CNR), Unità di Perugia, I-06123 Perugia (Italy); Del Bianco, L. [Department of Physics and Astronomy, University of Bologna, I-40127 Bologna (Italy); Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Bonfiglioli, E.; Giovannini, L.; Spizzo, F.; Zivieri, R. [Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Tamisari, M. [Department of Physics and Earth Sciences and CNISM, University of Ferrara, I-44122 Ferrara (Italy); Dipartimento di Fisica e Geologia, Università di Perugia, I-06123 Perugia (Italy)

    2015-05-07

    Brillouin light scattering (BLS) was exploited to study the spin wave properties of spin-valve (SV) type samples basically consisting of two 5 nm-thick NiFe layers (separated by a Cu spacer of 5 nm), differently biased through the interface exchange coupling with an antiferromagnetic IrMn layer. Three samples were investigated: a reference SV sample, without IrMn (reference); one sample with an IrMn underlayer (10 nm thick) coupled to the bottom NiFe film; one sample with IrMn underlayer and overlayer of different thickness (10 nm and 6 nm), coupled to the bottom and top NiFe film, respectively. The exchange coupling with the IrMn, causing the insurgence of the exchange bias effect, allowed the relative orientation of the NiFe magnetization vectors to be controlled by an external magnetic field, as assessed through hysteresis loop measurements by magneto-optic magnetometry. Thus, BLS spectra were acquired by sweeping the magnetic field so as to encompass both the parallel and antiparallel alignment of the NiFe layers. The BLS results, well reproduced by the presented theoretical model, clearly revealed the combined effects on the spin dynamic properties of the dipolar interaction between the two NiFe films and of the interface IrMn/NiFe exchange coupling.

  19. Tunneling Planar Hall Effect in Topological Insulators: Spin Valves and Amplifiers.

    Science.gov (United States)

    Scharf, Benedikt; Matos-Abiague, Alex; Han, Jong E; Hankiewicz, Ewelina M; Žutić, Igor

    2016-10-14

    We investigate tunneling across a single ferromagnetic barrier on the surface of a three-dimensional topological insulator. In the presence of a magnetization component along the bias direction, a tunneling planar Hall conductance (TPHC), transverse to the applied bias, develops. Electrostatic control of the barrier enables a giant Hall angle, with the TPHC exceeding the longitudinal tunneling conductance. By changing the in-plane magnetization direction, it is possible to change the sign of both the longitudinal and transverse differential conductance without opening a gap in the topological surface state. The transport in a topological-insulator-ferromagnet junction can, thus, be drastically altered from a simple spin valve to an amplifier.

  20. Rankine cycle condenser pressure control using an energy conversion device bypass valve

    Science.gov (United States)

    Ernst, Timothy C; Nelson, Christopher R; Zigan, James A

    2014-04-01

    The disclosure provides a waste heat recovery system and method in which pressure in a Rankine cycle (RC) system of the WHR system is regulated by diverting working fluid from entering an inlet of an energy conversion device of the RC system. In the system, an inlet of a controllable bypass valve is fluidly coupled to a working fluid path upstream of an energy conversion device of the RC system, and an outlet of the bypass valve is fluidly coupled to the working fluid path upstream of the condenser of the RC system such that working fluid passing through the bypass valve bypasses the energy conversion device and increases the pressure in a condenser. A controller determines the temperature and pressure of the working fluid and controls the bypass valve to regulate pressure in the condenser.

  1. Flow visualization of a monoleaflet and bileaflet mechanical heart valve in a pneumatic ventricular assist device using a PIV system.

    Science.gov (United States)

    Lee, Hwansung; Tatsumi, Eisuke; Taenaka, Yoshiyuki

    2010-01-01

    Our group is developing a new type of pulsatile pneumatic ventricular assist device (PVAD) that uses the Medtronic Hall tilting disc valve (M-H valve). Although tilting disc valves have good washout effect inside the blood pump, they are no longer in common clinical use and may be difficult to obtain in the future. To investigate the stability of the Sorin Bicarbon valve (S-B valve) in our PVAD, we constructed a model pump made of an acrylic resin with the same configuration as our PVAD and attempted to compare the flow visualization upstream and downstream of the outlet position valve between the M-H valve and the S-B valve using a particle image velocimetry (PIV) method. The outlet S-B valve had faster closure than the M-H valve. The maximum flow velocity was greater than with the M-H valve. The maximum Reynolds shear stress (RSS) of the M-H valve reached 150 N/m(2) and that of the S-B valve reached 300 N/m(2) upstream during the end-systolic and early-diastolic phases. In both valves, the maximum RSS upstream of the valve was higher than downstream of the valve because of the regurgitation flow during valve closure. In addition, the maximum viscous shear stress reached above 2 N/m(2), which occupied only about 1%-1.5% of the maximum RSS.

  2. A device for simultaneous spin analysis of ultracold neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Afach, S. [Institute for Particle Physics, ETH Zuerich, Zuerich (Switzerland); Paul Scherrer Institute, Villigen-PSI (Switzerland); Jena University Hospital, Hans Berger Department of Neurology, Jena (Germany); Ban, G.; Lefort, T.; Lemiere, Y.; Naviliat-Cuncic, O.; Quemener, G. [Universite de Caen, CNRS/IN2P3, LPC Caen ENSICAEN, Caen (France); Bison, G.; Chowdhuri, Z.; Daum, M.; Henneck, R.; Lauss, B.; Mtchedlishvili, A.; Schmidt-Wellenburg, P.; Zsigmond, G. [Paul Scherrer Institute, Villigen-PSI (Switzerland); Bodek, K.; Rawlik, M.; Rozpedzik, D.; Zejma, J. [Jagiellonian University, Marian Smoluchowski Institute of Physics, Cracow (Poland); Fertl, M.; Franke, B.; Kirch, K.; Komposch, S. [Institute for Particle Physics, ETH Zuerich, Zuerich (Switzerland); Paul Scherrer Institute, Villigen-PSI (Switzerland); Geltenbort, P. [Institut Laue-Langevin, Grenoble (France); Grujic, Z.D.; Kasprzak, M.; Weis, A. [University of Fribourg, Physics Department, Fribourg (Switzerland); Hayen, L.; Severijns, N.; Wursten, E. [Katholieke Universiteit Leuven, Instituut voor Kernen Stralingsfysica, Leuven (Belgium); Helaine, V. [Paul Scherrer Institute, Villigen-PSI (Switzerland); Universite de Caen, CNRS/IN2P3, LPC Caen ENSICAEN, Caen (France); Kermaidic, Y.; Pignol, G.; Rebreyend, D. [Universite Grenoble Alpes, CNRS/IN2P3, LPSC, Grenoble (France); Kozela, A. [Henryk Niedwodniczanski Institute for Nuclear Physics, Cracow (Poland); Krempel, J.; Piegsa, F.M. [Institute for Particle Physics, ETH Zuerich, Zuerich (Switzerland); Prashanth, P.N. [Paul Scherrer Institute, Villigen-PSI (Switzerland); Katholieke Universiteit Leuven, Instituut voor Kernen Stralingsfysica, Leuven (Belgium); Ries, D. [Paul Scherrer Institute, Villigen-PSI (Switzerland); Jena University Hospital, Hans Berger Department of Neurology, Jena (Germany); Roccia, S. [Universite Paris Sud, CNRS/IN2P3, CSNSM, Orsay campus (France); Wyszynski, G. [Institute for Particle Physics, ETH Zuerich, Zuerich (Switzerland); Jagiellonian University, Marian Smoluchowski Institute of Physics, Cracow (Poland)

    2015-11-15

    We report on the design and first tests of a device allowing for measurement of ultracold neutrons polarisation by means of the simultaneous analysis of the two spin components. The device was developed in the framework of the neutron electric dipole moment experiment at the Paul Scherrer Institute. Individual parts and the entire newly built system have been characterised with ultracold neutrons. The gain in statistical sensitivity obtained with the simultaneous spin analyser is (18.2 ± 6.1) % relative to the former sequential analyser under nominal running conditions. (orig.)

  3. Anomalous superconducting spin-valve effect in NbN/FeN/Cu/FeN/FeMn multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Tae Jong; Kim, Dong Ho [Yeungnam University, Gyeongsan (Korea, Republic of)

    2017-09-15

    We have studied magnetic and transport properties of NbN/FeN/Cu/FeN/FeMn spin-valve structure. In-plane magnetic moment exhibited typical hysteresis loops of spin valves in the normal state of NbN film at 20 K. On the other hand, the magnetic hysteresis loop in the superconducting state exhibited more complex behavior in which exchange bias provided by antiferrmagnetic FeMn layer to adjacent FeN layer was disturbed by superconductivity. Because of this, the ideal superconducting spin-valve effect was not detected. Instead the stray field originated from unsaturated magnetic states dominated the transport properties of NbN/FeN/Cu/FeN/FeMn multilayer.

  4. Strain-Induced Spin-Resonance Shifts in Silicon Devices

    Science.gov (United States)

    Pla, J. J.; Bienfait, A.; Pica, G.; Mansir, J.; Mohiyaddin, F. A.; Zeng, Z.; Niquet, Y. M.; Morello, A.; Schenkel, T.; Morton, J. J. L.; Bertet, P.

    2018-04-01

    In spin-based quantum-information-processing devices, the presence of control and detection circuitry can change the local environment of a spin by introducing strain and electric fields, altering its resonant frequencies. These resonance shifts can be large compared to intrinsic spin linewidths, and it is therefore important to study, understand, and model such effects in order to better predict device performance. We investigate a sample of bismuth donor spins implanted in a silicon chip, on top of which a superconducting aluminum microresonator is fabricated. The on-chip resonator provides two functions: it produces local strain in the silicon due to the larger thermal contraction of the aluminum, and it enables sensitive electron spin-resonance spectroscopy of donors close to the surface that experience this strain. Through finite-element strain simulations, we are able to reconstruct key features of our experiments, including the electron spin-resonance spectra. Our results are consistent with a recently observed mechanism for producing shifts of the hyperfine interaction for donors in silicon, which is linear with the hydrostatic component of an applied strain.

  5. Spin-motive Force Induced by Domain Wall Dynamics in the Antiferromagnetic Spin Valve

    Science.gov (United States)

    Sugano, Ryoko; Ichimura, Masahiko; Takahashi, Saburo; Maekawa, Sadamichi; Crest Collaboration

    2014-03-01

    In spite of no net magnetization in antiferromagnetic (AF) textures, the local magnetic properties (Neel magnetization) can be manipulated in a similar fashion to ferromagnetic (F) ones. It is expected that, even in AF metals, spin transfer torques (STTs) lead to the domain wall (DW) motion and that the DW motion induces spin-motive force (SMF). In order to study the Neel magnetization dynamics and the resultant SMF, we treat the nano-structured F1/AF/F2 junction. The F1 and F2 leads behave as a spin current injector and a detector, respectively. Each F lead is fixed in the different magnetization direction. Torsions (DW in AF) are introduced reflecting the fixed magnetization of two F leads. We simulated the STT-induced Neel magnetization dynamics with the injecting current from F1 to F2 and evaluate induced SMF. Based on the adiabatic electron dynamics in the AF texture, Langevin simulations are performed at finite temperature. This research was supported by JST, CREST, Japan.

  6. Ultra-low-pressure sputtering to improve exchange bias and tune linear ranges in spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Tang, XiaoLi, E-mail: tangtang1227@163.com; Yu, You; Liu, Ru; Su, Hua; Zhang, HuaiWu; Zhong, ZhiYong; Jing, YuLan

    2017-05-01

    A series of CoFe/IrMn exchange bilayers was grown by DC-sputtering at different ultra-low argon pressures ranging from 0.008 to 0.1 Pa. This pressure range was one to two orders lower than the normal sputtering pressure. Results revealed that the exchange bias increased from 140 to 250 Oe in CoFe(10 nm)/IrMn (15 nm) bilayers of fixed thickness because of the improved crystalline structure and morphological uniformity of films. Since ferromagnetic /antiferromagnetic (FM/AF) bilayers are always used in linear magnetic sensors as detection layers, the varying exchange bias can successfully achieve tunable linear range in a crossed pinning spin valve. The linear range could be adjustable from −80 Oe – +80 Oe to −150 Oe – +150 Oe on the basis of giant magnetoresistance responses. Therefore, this method provides a simple method to tune the operating range of magnetic field sensors. - Highlights: • Increasing exchange bias was achieved in bilayer at ultra-low-pressure sputtering. • The low void density and smooth surface were achieved in low pressure. • Varying exchange bias achieved tunable linear range in spin valve.

  7. Magnetic transport property of NiFe/WSe{sub 2}/NiFe spin valve structure

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Kangkang [Key Lab of Opto-electronics Technology, Ministry of Education, College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China); Key Lab of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China); Xing, Yanhui, E-mail: xingyanhui@bjut.edu.cn [Key Lab of Opto-electronics Technology, Ministry of Education, College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China); Han, Jun [Key Lab of Opto-electronics Technology, Ministry of Education, College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China); Feng, Jiafeng [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences (CAS), Beijing 100190 (China); Shi, Wenhua; Zhang, Baoshun [Key Lab of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China); Zeng, Zhongming, E-mail: zmzeng2012@sinano.ac.cn [Key Lab of Nanodevices and Applications, Suzhou Institute of Nano-Tech and Nano-Bionics, Chinese Academy of Sciences (CAS), Suzhou 215123 (China)

    2017-06-15

    Highlight: • Two-dimensional (2D) materials have been proposed as promising candidate for spintronic applications due to their atomic crystal structure and physical properties. • In this article, we introduce exfoliated few-layer tungsten diselenide (WSe{sub 2}) as spacer in a Py/WSe{sub 2}/Py vertical spin valve. • In this junction, the WSe{sub 2} spacer exhibits metallic behavior. • We observed negative magnetoresistance (MR) with a ratio of −1.1% at 4 K and −0.21% at 300 K. • A general phenomenological analysis of the negative MR property is discussed. • Our result is anticipated to be beneficial for future spintronic applications. - Abstract: Two-dimensional (2D) materials have been proposed as promising candidate for spintronic applications due to their atomic crystal structure and physical properties. Here, we introduce exfoliated few-layer tungsten diselenide (WSe{sub 2}) as spacer in a Py/WSe{sub 2}/Py vertical spin valve. In this junction, the WSe{sub 2} spacer exhibits metallic behavior. We observed negative magnetoresistance (MR) with a ratio of −1.1% at 4 K and −0.21% at 300 K. A general phenomenological analysis of the negative MR property is discussed. Our result is anticipated to be beneficial for future spintronic applications.

  8. Magnetic field devices for neutron spin transport and manipulation in precise neutron spin rotation measurements

    Energy Technology Data Exchange (ETDEWEB)

    Maldonado-Velázquez, M. [Posgrado en Ciencias Físicas, Universidad Nacional Autónoma de México, 04510 (Mexico); Barrón-Palos, L., E-mail: libertad@fisica.unam.mx [Instituto de Física, Universidad Nacional Autónoma de México, Apartado Postal 20-364, 01000 (Mexico); Crawford, C. [University of Kentucky, Lexington, KY 40506 (United States); Snow, W.M. [Indiana University, Bloomington, IN 47405 (United States)

    2017-05-11

    The neutron spin is a critical degree of freedom for many precision measurements using low-energy neutrons. Fundamental symmetries and interactions can be studied using polarized neutrons. Parity-violation (PV) in the hadronic weak interaction and the search for exotic forces that depend on the relative spin and velocity, are two questions of fundamental physics that can be studied via the neutron spin rotations that arise from the interaction of polarized cold neutrons and unpolarized matter. The Neutron Spin Rotation (NSR) collaboration developed a neutron polarimeter, capable of determining neutron spin rotations of the order of 10{sup −7} rad per meter of traversed material. This paper describes two key components of the NSR apparatus, responsible for the transport and manipulation of the spin of the neutrons before and after the target region, which is surrounded by magnetic shielding and where residual magnetic fields need to be below 100 μG. These magnetic field devices, called input and output coils, provide the magnetic field for adiabatic transport of the neutron spin in the regions outside the magnetic shielding while producing a sharp nonadiabatic transition of the neutron spin when entering/exiting the low-magnetic-field region. In addition, the coils are self contained, forcing the return magnetic flux into a compact region of space to minimize fringe fields outside. The design of the input and output coils is based on the magnetic scalar potential method.

  9. Enhanced spin accumulation in Fe3O4 based spin injection devices below the Verwey transition

    Science.gov (United States)

    Bhat, Shwetha G.; Kumar, P. S. Anil

    2016-12-01

    Spin injection into GaAs and Si (both n and p-type) semiconductors using Fe3O4 is achieved with and without a tunnel barrier (MgO) via three-terminal electrical Hanle measurement. Interestingly, the magnitude of spin accumulation voltage (ΔV) in semiconductor is found to be associated with a drastic increment in ΔV in Fe3O4 based devices for temperature metal-to-insulator transition of Fe3O4 at T V. Observations from our elaborate investigations show that spin polarization of Fe3O4 has an explicit influence on the enhanced spin injection. It is argued that the theoretical prediction of half-metallicity of Fe3O4 above and below T V has to be reinvestigated.

  10. Measurement of variable magnetic reversal paths in electrically contacted pseudo-spin-valve rings

    International Nuclear Information System (INIS)

    Hayward, T J; Llandro, J; Schackert, F D O; Morecroft, D; Balsod, R B; Bland, J A C; Castano, F J; Ross, C A

    2007-01-01

    In this work we show that the measurement of single magnetic reversal events is of critical importance in order to correctly characterize the switching of magnetic microstructures. Magnetoresistance measurements are performed on two pseudo-spin-valve ring structures with high enough signal to noise to allow the probing of single reversal events. Using this technique we acquire 'switching spectra' which demonstrate that the rings exhibit a range of variable reversal paths, including a bistable reversal mechanism of the hard layer, where the two switching routes have substantially different switching fields. The signature of the variable reversal paths would have been obscured in field cycle averaged data and in the bistable case would cause a fundamental misinterpretation of the reversal behaviour

  11. Controllable spin-charge transport in strained graphene nanoribbon devices

    Energy Technology Data Exchange (ETDEWEB)

    Diniz, Ginetom S., E-mail: ginetom@gmail.com; Guassi, Marcos R. [Institute of Physics, University of Brasília, 70919-970, Brasília-DF (Brazil); Qu, Fanyao [Institute of Physics, University of Brasília, 70919-970, Brasília-DF (Brazil); Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States)

    2014-09-21

    We theoretically investigate the spin-charge transport in two-terminal device of graphene nanoribbons in the presence of a uniform uniaxial strain, spin-orbit coupling, exchange field, and smooth staggered potential. We show that the direction of applied strain can efficiently tune strain-strength induced oscillation of band-gap of armchair graphene nanoribbon (AGNR). It is also found that electronic conductance in both AGNR and zigzag graphene nanoribbon (ZGNR) oscillates with Rashba spin-orbit coupling akin to the Datta-Das field effect transistor. Two distinct strain response regimes of electronic conductance as function of spin-orbit couplings magnitude are found. In the regime of small strain, conductance of ZGNR presents stronger strain dependence along the longitudinal direction of strain. Whereas for high values of strain shows larger effect for the transversal direction. Furthermore, the local density of states shows that depending on the smoothness of the staggered potential, the edge states of AGNR can either emerge or be suppressed. These emerging states can be determined experimentally by either spatially scanning tunneling microscope or by scanning tunneling spectroscopy. Our findings open up new paradigms of manipulation and control of strained graphene based nanostructure for application on novel topological quantum devices.

  12. Role of passive valves & devices in poison injection system of advanced heavy water reactor

    International Nuclear Information System (INIS)

    Sapra, M.K.; Kundu, S.; Vijayan, P.K.; Vaze, K.K.; Sinha, R.K.

    2014-01-01

    The Advanced Heavy Water Reactor (AHWR) is a 300 MWe pressure tube type boiling light water (H 2 O) cooled, heavy water (D 2 O) moderated reactor. The reactor design is based on well-proven water reactor technologies and incorporates a number of passive safety features such as natural circulation core cooling; direct in-bundle injection of light water coolant during a Loss of Coolant Accident (LOCA) from Advanced Accumulators and Gravity Driven Water Pool by passive means; Passive Decay Heat Removal using Isolation Condensers, Passive Containment Cooling System and Passive Containment Isolation System. In addition to above, there is another passive safety system named as Passive Poison Injection System (PPIS) which is capable of shutting down the reactor for a prolonged time. It is an additional safety system in AHWR to fulfill the shutdown function in the event of failure of wired shutdown systems i.e. primary and secondary shut down systems of the reactor. When demanded, PPIS injects the liquid poison into the moderator by passive means using passive valves and devices. On increase of main heat transport (MHT) system pressure beyond a predetermined value, a set of rupture disks burst, which in-turn actuate the passive valve. The opening of passive valve initiates inrush of high pressure helium gas into poison tanks to push the poison into the moderator system, thereby shutting down the reactor. This paper primarily deals with design and development of Passive Poison Injection System (PPIS) and its passive valves & devices. Recently, a prototype DN 65 size Poison Injection Passive Valve (PIPV) has been developed for AHWR usage and tested rigorously under simulated conditions. The paper will highlight the role of passive valves & devices in PPIS of AHWR. The design concept and test results of passive valves along with rupture disk performance will also be covered. (author)

  13. Ferromagnetic resonance study of the half-Heusler alloy NiMnSb. The benefit of using NiMnSb as a ferromagnetic layer in pseudo-spin-valve based spin-torque oscillators

    Energy Technology Data Exchange (ETDEWEB)

    Riegler, Andreas

    2011-11-25

    Since the discovery of spin torque in 1996, independently by Berger and Slonczewski, and given its potential impact on information storage and communication technologies, (e.g. through the possibility of switching the magnetic configuration of a bit by current instead of a magnetic field, or the realization of high frequency spin torque oscillators (STO)), this effect has been an important field of spintronics research. One aspect of this research focuses on ferromagnets with low damping. The lower the damping in a ferromagnet, the lower the critical current that is needed to induce switching of a spin valve or induce precession of its magnetization. In this thesis ferromagnetic resonance (FMR) studies of NiMnSb layers are presented along with experimental studies on various spin-torque (ST) devices using NiMnSb. NiMnSb, when crystallized in the half-Heusler structure, is a half-metal which is predicted to have 100% spin polarization, a consideration which further increases its potential as a candidate for memory devices based on the giant magnetoresistance (GMR) effect. The FMR measurements show an outstandingly low damping factor for NiMnSb, in low 10{sup -3} range. This is about a factor of two lower than permalloy and well comparable to lowest damping for iron grown by molecular beam epitaxy (MBE). According to theory the 100% spin polarization properties of the bulk disappear at interfaces where the break in translational symmetry causes the gap in the minority spin band to collapse but can remain in other crystal symmetries such as (111). Consequently NiMnSb layers on (111)(In,Ga)As buffer are characterized in respect of anisotropies and damping. The FMR measurements on these samples indicates a higher damping that for the 001 samples, and a thickness dependent uniaxial in-plane anisotropy. Investigations of the material for device use is pursued by considering sub-micrometer sized elements of NiMnSb on 001 substrates, which were fabricated by electron

  14. Spin-valves with modified synthetic antiferromagnets exhibiting an enhanced bias point control capability at submicrometer dimensions

    International Nuclear Information System (INIS)

    Park, J.-S.; Lee, S.-R.; Kim, Y.K.

    2004-01-01

    Bias point control is of practical importance for operating read sensors for magnetic recording and magnetic random access memory devices. To attain bias point control capability, in particular, at submicrometer cell size, a modified synthetic antiferromagnet-based spin-valve (MSSV) structure was devised. A series of calculations were carried out to investigate the effect of size variation on their MR transfer behaviors. The cell dimension was varied from 10 to 0.05 μm. The typical MSSV comprises IrMn (9.0)/CoFe (P1, 1.5)/Ru (0.7)/CoFe (P2, 3.0)/Ru (0.7)/CoFe (P3, 1.5)/Cu (2.8)/CoFe (1.6)/NiFe (3.2) (in nm). As the cell size decreased, the bias point in the MSSV maintained nearly zero regardless of the cell size. The bias point was further tuned by varying the P3 layer thickness. Moreover, the effective exchange field (H ex.eff ) of the MSSV was much larger than that of the conventional SSV. The field sensitivity of the MSSV was very high indicating that the free layer can rotate more sharply

  15. Spin-valves with modified synthetic antiferromagnets exhibiting an enhanced bias point control capability at submicrometer dimensions

    Science.gov (United States)

    Park, Jeong-Suk; Lee, Seong-Rae; Kim, Young Keun

    2004-08-01

    Bias point control is of practical importance for operating read sensors for magnetic recording and magnetic random access memory devices. To attain bias point control capability, in particular, at submicrometer cell size, a modified synthetic antiferromagnet-based spin-valve (MSSV) structure was devised. A series of calculations were carried out to investigate the effect of size variation on their MR transfer behaviors. The cell dimension was varied from 10 to 0.05 μm. The typical MSSV comprises IrMn (9.0)/CoFe (P1, 1.5)/Ru (0.7)/CoFe (P2, 3.0)/Ru (0.7)/CoFe (P3, 1.5)/Cu (2.8)/CoFe (1.6)/NiFe (3.2) (in nm). As the cell size decreased, the bias point in the MSSV maintained nearly zero regardless of the cell size. The bias point was further tuned by varying the P3 layer thickness. Moreover, the effective exchange field ( Hex.eff) of the MSSV was much larger than that of the conventional SSV. The field sensitivity of the MSSV was very high indicating that the free layer can rotate more sharply.

  16. Cardiac implantable electronic device and associated risk of infective endocarditis in patients undergoing aortic valve replacement

    DEFF Research Database (Denmark)

    Østergaard, Lauge; Valeur, Nana; Bundgaard, Henning

    2017-01-01

    Aims: Patients undergoing aortic valve replacement (AVR) are at increased risk of infective endocarditis (IE) as are patients with a cardiac implantable electronic device (CIED). However, few data exist on the IE risk after AVR surgery in patients with a CIED. Methods and results: Using the Danish...

  17. Spin-splitting in p-type Ge devices

    Energy Technology Data Exchange (ETDEWEB)

    Holmes, S. N., E-mail: s.holmes@crl.toshiba.co.uk; Newton, P. J.; Llandro, J.; Mansell, R.; Barnes, C. H. W. [Cavendish Laboratory, Department of Physics, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Morrison, C.; Myronov, M. [Department of Physics, University of Warwick, Coventry CV4 7AL (United Kingdom)

    2016-08-28

    Compressively strained Ge quantum well devices have a spin-splitting in applied magnetic field that is entirely consistent with a Zeeman effect in the heavy hole valence band. The spin orientation is determined by the biaxial strain in the quantum well with the relaxed SiGe buffer layers and is quantized in the growth direction perpendicular to the conducting channel. The measured spin-splitting in the resistivity ρ{sub xx} agrees with the predictions of the Zeeman Hamiltonian where the Shubnikov-deHaas effect exhibits a loss of even filling factor minima in the resistivity ρ{sub xx} with hole depletion from a gate field, increasing disorder or increasing temperature. There is no measurable Rashba spin-orbit coupling irrespective of the structural inversion asymmetry of the confining potential in low p-doped or undoped Ge quantum wells from a density of 6 × 10{sup 10} cm{sup −2} in depletion mode to 1.7 × 10{sup 11} cm{sup −2} in enhancement.

  18. Use of an Automated Suture Fastening Device in Minimally Invasive Aortic Valve Replacement.

    Science.gov (United States)

    Beute, Tyler J; Orem, Matthew D; Schiller, Timothy M; Goehler, Matthew; Parker, Jessica; Willekes, Charles L; Timek, Tomasz

    2018-03-01

    Minimally invasive aortic valve replacement (mAVR) is gaining clinical acceptance, however, it is associated with increased operative times due to limited surgical field and access. The Cor-Knot is an automated fastening device designed to facilitate suture fastening, but clinical data in mAVR are lacking. From May 2014 to February 2017, 92 patients underwent mAVR at our center with 39 valves secured with manually-tied (MT) sutures and 53 valves entirely secured with the Cor-Knot (CK). Pre-operative characteristics and 30-day outcomes data were extracted from our local Society of Thoracic Surgeons database and the electronic medical record. Survival data were obtained from the Michigan State Social Security Death Index. No significant difference in pre-operative characteristics were noted between the two groups. Aortic cross-clamp time (72±12 min vs 82±15 min, p=0.001) was significantly shorter with CK. There was no difference in post-operative mortality (0% vs 0%), stroke (0% vs 1.9%), atrial fibrillation (28% vs 33%), renal failure (0% vs 3.8%), or pacemaker implantation (5.1% vs 5.7%) between MT and CK. Valve function on post-operative echocardiography and 1-year patient survival were similar. In minimally invasive aortic valve replacement, the Cor-Knot device was associated with reduced aortic cross-clamp time while providing equivalent clinical outcomes. Larger studies are needed to confirm efficacy, safety, and cost-effectiveness of the Cor-Knot device in minimally invasive aortic valve surgery. Copyright © 2018 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  19. Steps toward an all-electric spin valve using side-gated quantum point contacts with lateral spin-orbit coupling

    Science.gov (United States)

    Bhandari, Nikhil; Dutta, Maitreya; Charles, James; Newrock, Richard S.; Cahay, Marc; Herbert, Stephen T.

    2013-03-01

    Spin-based electronics or ‘spintronics’ has been a topic of interest for over two decades. Electronic devices based on the manipulation of the electron spin are believed to offer the possibility of very small, non-volatile and ultrafast devices with very low power consumption. Since the proposal of a spin-field-effect transistor (SpinFET) by Datta and Das in 1990, many attempts have been made to achieve spin injection, detection and manipulation in semiconductor materials either by incorporating ferromagnetic materials into device architectures or by using external magnetic fields. This approach has significant design complexities, partly due to the influence of stray magnetic fields on device operation. In addition, magnetic electrodes can have magneto-resistance and spurious Hall voltages that can complicate device performance. To date, there has been no successful report of a working Datta-Das SpinFET. Over the last few years we have investigated an all-electric means of manipulating spins, one that only relies on electric fields and voltages and not on ferromagnetic materials or external magnetic fields. We believe we have found a pathway toward this goal, using in-plane side-gated quantum point contacts (QPCs) that rely on lateral spin-orbit coupling to create spin polarization. In this paper we discuss several aspects of our work, beginning with our finding what we believe is nearly complete spin-polarization in InAs QPCs by purely electrical means, our theoretical work to understand the basic mechanisms leading to that situation (asymmetric lateral confinement, lateral spin-orbit coupling and a strong e-e interaction), and our recent work extending the effort to GaAs and to dual QPC systems where one QPC acts as a polarizer and the other as an analyzer. Keynote talk at the 6th International Workshop on Advanced Materials Science and Nanotechnology, 30 October-2 November 2012, Ha Long, Vietnam.

  20. Chemical properties and GMR improvement of specular spin valves with nano-oxide layers, formed in ambient mixed gases

    International Nuclear Information System (INIS)

    Quang, H D; Hien, N T; Oh, S K; Sinh, N H; Yu, S C

    2004-01-01

    Specular spin valves (SVs) containing nano-oxide layers (NOLs) structured as substrate/seed/AF/P 1 /NOL/P 2 /Cu/F/NOL, have been fabricated. The NOLs were formed by natural oxidation in different ambient atmospheres of pure oxygen, oxygen/nitrogen and oxygen/argon gas mixtures. The fabrication conditions were optimized to enhance the magnetoresistance (MR) ratio, to suppress the interlayer coupling fields (H f ) between the free and pinned layers, to suppress the high interface density of the NOL, to ease the control of the NOL thickness and to form a smooth NOL/P 2 interface for promoting specular electron scattering. The characteristics of our specular SVs are the MR ratio of 14.1%, the exchange bias field of 44-45 mT, and H f weaker than 1.0 mT. The optimal conditions for oxidation time, total oxidation pressure and the annealing temperature were found to be 300 s, 0.14 Pa (oxygen/argon = 80/20) and 250 deg. C, respectively. Also, the origin of thermal stability of MMn-based (M = Fe, Pt, Ir, etc) specular SVs has been explained in detail by chemical properties of NOL using secondary-ion mass spectroscopy and x-ray photoelectron spectroscopy depth profile analyses. Thermal stability turns out to be caused by a decrease in MR ratios at high temperatures (>250 deg. C), which is a serious problem for device applications using the SV structure as a high density read head device

  1. Catheterization Laboratory: Structural Heart Disease, Devices, and Transcatheter Aortic Valve Replacement.

    Science.gov (United States)

    Fiorilli, Paul N; Anwaruddin, Saif; Zhou, Elizabeth; Shah, Ronak

    2017-12-01

    The cardiac catheterization laboratory is advancing medicine by performing procedures on patients who would usually require sternotomy and cardiopulmonary bypass. These procedures are done percutaneously, allowing them to be performed on patients considered inoperable. Patients have compromised cardiovascular function or advanced age. An anesthesiologist is essential for these procedures in case of hemodynamic compromise. Interventionalists are becoming more familiar with transcatheter aortic valve replacement and the device has become smaller, both contributing to less complications. Left atrial occlusion and the endovascular edge-to-edge mitral valve repair devices were approved. Although these devices require general anesthesia, an invasive surgery and cardiopulmonary bypass machine are not necessary for deployment. Copyright © 2017 Elsevier Inc. All rights reserved.

  2. The anchoring effect on the spin transport properties and I-V characteristics of pentacene molecular devices suspended between nickel electrodes.

    Science.gov (United States)

    Caliskan, S; Laref, A

    2014-07-14

    Spin-polarized transport properties are determined for pentacene sandwiched between Ni surface electrodes with various anchoring ligands. These calculations are carried out using spin density functional theory in tandem with a non-equilibrium Green's function technique. The presence of a Se atom at the edge of the pentacene molecule significantly modifies the transport properties of the device because Se has a different electronegativity than S. Our theoretical results clearly show a larger current for spin-up electrons than for spin-down electrons in the molecular junction that is attached asymmetrically across the Se linker at one side of the Ni electrodes (in an APL magnetic orientation). Moreover, this molecular junction exhibits pronounced NDR as the bias voltage is increased from 0.8 to 1.0 V. However, this novel NDR behavior is only detected in this promising pentacene molecular device. The NDR in the current-voltage (I-V) curve results from the narrowness of the density of states for the molecular states. The feasibility of controlling the TMR is also predicted in these molecular device nanostructures. Spin-dependent transmission calculations show that the sign and strength of the current-bias voltage characteristics and the TMR could be tailored for the organic molecule devices. These molecular junctions are joined symmetrically and asymmetrically between Ni metallic probes across the S and Se atoms (at the ends of the edges of the pentacene molecule). Our theoretical findings show that spin-valve phenomena can occur in these prototypical molecular junctions. The TMR and NDR results show that nanoscale junctions with spin valves could play a vital role in the production of novel functional molecular devices.

  3. Nanostructures based on superconducting Nb and ferromagnetic CuNi alloy for elaboration of spin-valve core

    International Nuclear Information System (INIS)

    Morari, Roman

    2013-01-01

    The main goal of our research group is the elaboration of superconducting spin-switch (valve) based on Ferromagnetic/Superconductor/Ferromagnetic core. We could realize all building blocks necessary for the fabrication of the core structure of the superconducting spin valve, consisting of two mirror symmetric bilayers. In other words, the spin valve consists of a F/S * /F trilayer, which can be regarded as a package of a F/S and S/F bilayer so that S * =2S in the trilayer. For such a trilayer, the theory predicts that the critical temperature depends on the relative orientation of the magnetization of the ferromagnetic layers. To enable a reversal of one of the magnetizations of the layers with respect to the other by an external magnetic field, the coercive forces of the F layers have to be different due to either intrinsic properties or to an antiferromagnetic pinning layer delivering an exchange bias. The main points of our study are presented here. (author)

  4. Thickness dependence of the triplet spin-valve effect in superconductor-ferromagnet heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Lenk, Daniel; Zdravkov, Vladimir I.; Kehrle, Jan; Obermeier, Guenther; Krug von Nidda, Hans-Albrecht; Mueller, Claus; Horn, Siegfried; Tidecks, Reinhard [Institut fuer Physik, Universitaet Augsburg (Germany); Morari, Roman [Institut fuer Physik, Universitaet Augsburg (Germany); D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Kishinev (Moldova, Republic of); Sidorenko, Anatolie S. [D. Ghitsu Institute of Electronic Engineering and Nanotechnologies ASM, Kishinev (Moldova, Republic of); Tagirov, Lenar [Solid State Physics Department, Kazan Federal University (Russian Federation)

    2015-07-01

    We investigated the triplet spin-valve effect in nanoscale layered S/F{sub 1}/N/F{sub 2}/AF heterostructures with varying F{sub 1}-layer thickness (where S=Nb is a singlet superconducting, F{sub 1}=Cu{sub 41}Ni{sub 59} and F{sub 2}=Co a ferromagnetic, and N a normal-conducting, non-magnetic layer). The theory predicts a long-range, odd-in-frequency triplet component of superconductivity at non-collinear alignment of the magnetizations of F{sub 1} and F{sub 2}. This triplet component exhausts the singlet state and, thus, lowers the superconducting transition temperature, T{sub c}, yielding a global minimum of T{sub c} close to the perpendicular mutual orientations of the magnetizations. We found an oscillating decay of T{sub c} suppression, due to the generation of the triplet component, with increasing F{sub 1} layer thickness, which we discuss in the framework of recent theories.

  5. Investigations of the polymer/magnetic interface of organic spin-valves

    Energy Technology Data Exchange (ETDEWEB)

    Morley, N.A., E-mail: n.a.morley@sheffield.ac.uk [Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Dost, R.; Lingam, A.S.V. [Department of Materials Science and Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD (United Kingdom); Barlow, A.J. [National EPSRC XPS Users’ Service, School of Mechanical and Systems Engineering, Newcastle University, Newcastle upon Tyne NE1 7RU (United Kingdom)

    2015-12-30

    Graphical abstract: - Highlights: • Metal carbide and sulphide species are detected at a polymer–magnetic interface. • Top magnetic electrodes on P3HT have uniaxial anisotropy. • Top magnetic electrodes on PBTTT are isotropic. - Abstract: This work investigates the top interface of an organic spin-valve, to determine the interactions between the polymer and top magnetic electrode. The polymers studied are regio-regular poly(3-hexylthiophene) (RR-P3HT) and poly(2,5-bis(3-hexadecylthiophen-2-yl)thieno[3,2-b]thiophene (PBTTT) and the magnetic top electrodes are NiFe and Fe. X-ray photoelectron spectroscopy (XPS) is used to determine the bonding at the interface, along with the extent of how oxidised the magnetic layers are, while atomic force microscopy (AFM) is used to determine the surface roughness. A magneto-optic Kerr effect (MOKE) magnetometer is used to study the magnetic properties of the top electrode. It is shown that at the organic–magnetic interface the magnetic atoms interact with the polymer, as metallic–sulphide and metallic-carbide species are present at the interface. It is also shown that the structure of the polymer influences the anisotropy of the magnetic electrode, such that the magnetic electrodes grown on RR-P3HT have uniaxial anisotropy, while those grown on PBTTT are isotropic.

  6. Ordinary and triplet superconducting spin valve effect in Fe/Pb based systems

    Energy Technology Data Exchange (ETDEWEB)

    Leksin, Pavel; Schumann, Joachim; Krupskaya, Yulia; Kataev, Vladislav; Hess, Christian; Schmidt, Oliver; Buechner, Bernd [Leibniz Institute for Solid State and Materials Research IFW Dresden (Germany); Garifyanov, Nadir; Garifullin, Ilgiz [Zavoisky Physical-Technical Institute of RAS, Kazan (Russian Federation); Fominov, Yakov [L. D. Landau Institute for Theoretical Physics of RAS, Moscow (Russian Federation)

    2015-07-01

    We report on experimental evidence for the occurrence of the long range triplet correlations (LRTC) of the superconducting (SC) condensate in the spin-valve heterostructures CoO{sub x}/Fe1/Cu/Fe2/Pb. The LRTC generation in this layer sequence is accompanied by a T{sub c} suppression near the orthogonal mutual orientation of the Fe1 and Fe2 layers' magnetization. This T{sub c} drop reaches its maximum of 60mK at the Fe2 layer thickness d{sub Fe2} = 0.6 nm and falls down when d{sub Fe2} is increased. The modification of the Fe/Pb interface by using a thin Cu layer between Fe and Pb layers reduces the SC transition width without preventing the interaction between Pb and Fe2 layers. The dependence of the SSVE magnitude on Fe1 layer thickness d{sub Fe1} reveals maximum of the effect when d{sub Fe1} and d{sub Fe2} are equal and the d{sub Fe2} value is minimal. Using the optimal d{sub Fe1}, d{sub Fe2} and the intermediate Cu layer we realized almost full switching from normal to SC state due to SSVE.

  7. Spin wave absorber generated by artificial surface anisotropy for spin wave device network

    Directory of Open Access Journals (Sweden)

    Naoki Kanazawa

    2016-09-01

    Full Text Available Spin waves (SWs have the potential to reduce the electric energy loss in signal processing networks. The SWs called magnetostatic forward volume waves (MSFVWs are advantageous for networking due to their isotropic dispersion in the plane of a device. To control the MSFVW flow in a processing network based on yttrium iron garnet, we developed a SW absorber using artificial structures. The mechanical surface polishing method presented in this work can well control extrinsic damping without changing the SW dispersion of the host material. Furthermore, enhancement of the ferromagnetic resonance linewidth over 3 Oe was demonstrated.

  8. Magnon Valve Effect between Two Magnetic Insulators

    Science.gov (United States)

    Wu, H.; Huang, L.; Fang, C.; Yang, B. S.; Wan, C. H.; Yu, G. Q.; Feng, J. F.; Wei, H. X.; Han, X. F.

    2018-03-01

    The key physics of the spin valve involves spin-polarized conduction electrons propagating between two magnetic layers such that the device conductance is controlled by the relative magnetization orientation of two magnetic layers. Here, we report the effect of a magnon valve which is made of two ferromagnetic insulators (YIG) separated by a nonmagnetic spacer layer (Au). When a thermal gradient is applied perpendicular to the layers, the inverse spin Hall voltage output detected by a Pt bar placed on top of the magnon valve depends on the relative orientation of the magnetization of two YIG layers, indicating the magnon current induced by the spin Seebeck effect at one layer affects the magnon current in the other layer separated by Au. We interpret the magnon valve effect by the angular momentum conversion and propagation between magnons in two YIG layers and conduction electrons in the Au layer. The temperature dependence of the magnon valve ratio shows approximately a power law, supporting the above magnon-electron spin conversion mechanism. This work opens a new class of valve structures beyond the conventional spin valves.

  9. Highly spin-polarized materials and devices for spintronics∗.

    Science.gov (United States)

    Inomata, Koichiro; Ikeda, Naomichi; Tezuka, Nobuki; Goto, Ryogo; Sugimoto, Satoshi; Wojcik, Marek; Jedryka, Eva

    2008-01-01

    The performance of spintronics depends on the spin polarization of the current. In this study half-metallic Co-based full-Heusler alloys and a spin filtering device (SFD) using a ferromagnetic barrier have been investigated as highly spin-polarized current sources. The multilayers were prepared by magnetron sputtering in an ultrahigh vacuum and microfabricated using photolithography and Ar ion etching. We investigated two systems of Co-based full-Heusler alloys, Co 2 Cr 1 - x Fe x Al (CCFA( x )) and Co 2 FeSi 1 - x Al x (CFSA( x )) and revealed the structure and magnetic and transport properties. We demonstrated giant tunnel magnetoresistance (TMR) of up to 220% at room temperature and 390% at 5 K for the magnetic tunnel junctions (MTJs) using Co 2 FeSi 0.5 Al 0.5 (CFSA(0.5)) Heusler alloy electrodes. The 390% TMR corresponds to 0.81 spin polarization for CFSA(0.5) at 5 K. We also investigated the crystalline structure and local structure around Co atoms by x-ray diffraction (XRD) and nuclear magnetic resonance (NMR) analyses, respectively, for CFSA films sputtered on a Cr-buffered MgO (001) substrate followed by post-annealing at various temperatures in an ultrahigh vacuum. The disordered structures in CFSA films were clarified by NMR measurements and the relationship between TMR and the disordered structure was discussed. We clarified that the TMR of the MTJs with CFSA(0.5) electrodes depends on the structure, and is significantly higher for L2 1 than B2 in the crystalline structure. The second part of this paper is devoted to a SFD using a ferromagnetic barrier. The Co ferrite is investigated as a ferromagnetic barrier because of its high Curie temperature and high resistivity. We demonstrate the strong spin filtering effect through an ultrathin insulating ferrimagnetic Co-ferrite barrier at a low temperature. The barrier was prepared by the surface plasma oxidization of a CoFe 2 film deposited on a MgO (001) single crystal substrate, wherein the spinel

  10. Topological Magnonics: A Paradigm for Spin-Wave Manipulation and Device Design

    Science.gov (United States)

    Wang, X. S.; Zhang, H. W.; Wang, X. R.

    2018-02-01

    Conventional magnonic devices use magnetostatic waves whose properties are sensitive to device geometry and the details of magnetization structure, so the design and the scalability of the device or circuitry are difficult. We propose topological magnonics, in which topological exchange spin waves are used as information carriers, that do not suffer from conventional problems of magnonic devices with additional nice features of nanoscale wavelength and high frequency. We show that a perpendicularly magnetized ferromagnet on a honeycomb lattice is generically a topological magnetic material in the sense that topologically protected chiral edge spin waves exist in the band gap as long as a spin-orbit-induced nearest-neighbor pseudodipolar interaction (and/or a next-nearest-neighbor Dzyaloshinskii-Moriya interaction) is present. The edge spin waves propagate unidirectionally along sample edges and domain walls regardless of the system geometry and defects. As a proof of concept, spin-wave diodes, spin-wave beam splitters, and spin-wave interferometers are designed by using sample edges and domain walls to manipulate the propagation of topologically protected chiral spin waves. Since magnetic domain walls can be controlled by magnetic fields or electric current or fields, one can essentially draw, erase, and redraw different spin-wave devices and circuitry on the same magnetic plate so that the proposed devices are reconfigurable and tunable. The topological magnonics opens up an alternative direction towards a robust, reconfigurable and scalable spin-wave circuitry.

  11. Template-grown NiFe/Cu/NiFe nanowires for spin transfer devices

    DEFF Research Database (Denmark)

    Piraux, L.; Renard, K.; Guillemet, R.

    2007-01-01

    We have developed a new reliable method combining template synthesis and nanolithography-based contacting technique to elaborate current perpendicular-to-plane giant magnetoresistance spin valve nanowires, which are very promising for the exploration of electrical spin transfer phenomena....... The method allows the electrical connection of one single nanowire in a large assembly of wires embedded in anodic porous alumina supported on Si substrate with diameters and periodicities to be controllable to a large extent. Both magnetic excitations and switching phenomena driven by a spin...

  12. Biomedical Impact in Implantable Devices-The Transcatheter Aortic Valve as an example

    Science.gov (United States)

    Anastasiou, Alexandros; Saatsakis, George

    2015-09-01

    Objective: To update of the scientific community about the biomedical engineering involvement in the implantable devices chain. Moreover the transcatheter Aortic Valve (TAV) replacement, in the field of cardiac surgery, will be analyzed as an example of contemporary implantable technology. Methods: A detailed literature review regarding biomedical engineers participating in the implantable medical product chain, starting from the design of the product till the final implantation technique. Results: The scientific role of biomedical engineers has clearly been established. Certain parts of the product chain are implemented almost exclusively by experienced biomedical engineers such as the transcatheter aortic valve device. The successful professional should have a multidisciplinary knowledge, including medicine, in order to pursue the challenges for such intuitive technology. This clearly indicates that biomedical engineers are among the most appropriate scientists to accomplish such tasks. Conclusions: The biomedical engineering involvement in medical implantable devices has been widely accepted by the scientific community, worldwide. Its important contribution, starting from the design and extended to the development, clinical trials, scientific support, education of other scientists (surgeons, cardiologists, technicians etc.), and even to sales, makes biomedical engineers a valuable player in the scientific arena. Notably, the sector of implantable devices is constantly raising, as emerging technologies continuously set up new targets.

  13. High-performance spinning device for DVD-based micromechanical signal transduction

    DEFF Research Database (Denmark)

    Hwu, En-Te; Chen, Ching-Hsiu; Bosco, Filippo

    2013-01-01

    Here we report a high-throughput spinning device for nanometric scale measurements of microstructures with instrumentation details and experimental results. The readout technology implemented in the designed disc-like device is based on a DVD data storage optical pick-up unit (OPU). With a spinning...

  14. Strong spin-filtering and spin-valve effects in a molecular V–C60–V contact

    Directory of Open Access Journals (Sweden)

    Mohammad Koleini

    2012-08-01

    Full Text Available Motivated by the recent achievements in the manipulation of C60 molecules in STM experiments, we study theoretically the structure and electronic properties of a C60 molecule in an STM tunneljunction with a magnetic tip and magnetic adatom on a Cu(111 surface using first-principles calculations. For the case of a vanadium tip/adatom, we demonstrate how spin coupling between the magnetic V atoms, mediated by the C60, can be observed in the electronic transport, which display a strong spin-filtering effect, allowing mainly majority-spin electrons to pass (>95%. Moreover, we find a significant change in the conductance between parallel and anti-parallel spin polarizations in the junction (86% which suggests that STM experiments should be able to characterize the magnetism and spin coupling for these systems.

  15. Strong spin-filtering and spin-valve effects in a molecular V-C-60-V contact

    DEFF Research Database (Denmark)

    Koleini, Mohammad; Brandbyge, Mads

    2012-01-01

    Motivated by the recent achievements in the manipulation of C-60 molecules in STM experiments, we study theoretically the structure and electronic properties of a C-60 molecule in an STM tunneljunction with a magnetic tip and magnetic adatom on a Cu(111) surface using first-principles calculations....... For the case of a vanadium tip/adatom, we demonstrate how spin coupling between the magnetic V atoms, mediated by the C-60, can be observed in the electronic transport, which display a strong spin-filtering effect, allowing mainly majority-spin electrons to pass (>95%). Moreover, we find a significant change...... in the conductance between parallel and anti-parallel spin polarizations in the junction (86%) which suggests that STM experiments should be able to characterize the magnetism and spin coupling for these systems....

  16. Effect of uniaxial strain on the tunnel magnetoresistance of T-shaped graphene nanoribbon based spin-valve

    Science.gov (United States)

    Fouladi, A. Ahmadi

    2016-07-01

    We theoretically investigated the spin-dependent transport through a T-shaped graphene nanoribbon (TsGNR) based spin-valve consisting of armchair graphene sandwiched between two semi-infinite ferromagnetic armchair graphene nanoribbon leads in the presence of an applied uniaxial strain. Based on a tight-binding model and standard nonequilibrium Green's function technique, it is demonstrated that the tunnel magnetoresistance (TMR) for the system can be increased about 98% by tuning the uniaxial strain. Our results show that the absolute values of TMR around the zero bias voltage for compressive strain are larger than tensile strain. In addition, the TMR of the system can be nicely controlled by GNR width.

  17. Spin-filtering and giant magnetoresistance effects in polyacetylene-based molecular devices

    Science.gov (United States)

    Chen, Tong; Yan, Shenlang; Xu, Liang; Liu, Desheng; Li, Quan; Wang, Lingling; Long, Mengqiu

    2017-07-01

    Using the non-equilibrium Green's function formalism in combination with density functional theory, we performed ab initio calculations of spin-dependent electron transport in molecular devices consisting of a polyacetylene (CnHn+1) chain vertically attached to a carbon chain sandwiched between two semi-infinite zigzag-edged graphene nanoribbon electrodes. Spin-charge transport in the device could be modulated to different magnetic configurations by an external magnetic field. The results showed that single spin conduction could be obtained. Specifically, the proposed CnHn+1 devices exhibited several interesting effects, including (dual) spin filtering, spin negative differential resistance, odd-even oscillation, and magnetoresistance (MR). Marked spin polarization with a filtering efficiency of up to 100% over a large bias range was found, and the highest MR ratio for the CnHn+1 junctions reached 4.6 × 104. In addition, the physical mechanisms for these phenomena were also revealed.

  18. Surgical treatment of tricuspid valve insufficiency promotes early reverse remodeling in patients with axial-flow left ventricular assist devices.

    Science.gov (United States)

    Maltais, Simon; Topilsky, Yan; Tchantchaleishvili, Vakhtang; McKellar, Stephen H; Durham, Lucian A; Joyce, Lyle D; Daly, Richard C; Park, Soon J

    2012-06-01

    The HeartMate II (Thoratec Corp, Pleasanton, Calif) continuous-flow left ventricular assist device has emerged as the standard of care for patients with advanced heart failure. The objective of this study was to assess the safety and early effectiveness of concomitant tricuspid valve procedures in patients undergoing implantation of a HeartMate II device. From February 2007 to April 2010, 83 patients underwent HeartMate II left ventricular assist device implantation. Of these, 37 patients had concomitant tricuspid valve procedures (32 repairs, 5 replacements) for severe tricuspid regurgitation. The effects of a tricuspid valve procedure on tricuspid regurgitation and right ventricular remodeling were assessed comparing echocardiographic findings at baseline and 30 days after left ventricular assist device implantation. Overall survival was also compared. Patients undergoing a concomitant tricuspid valve procedure had more tricuspid regurgitation (vena contracta, 5.6 ± 2.1 mm vs 2.9 ± 2.0 mm; P tricuspid regurgitation was worse in patients who underwent left ventricular assist device implantation alone (+18.6%), whereas it improved significantly in patients undergoing a concomitant tricuspid valve procedure (-50.2%) (P = .005). A corresponding significant reduction in right ventricular end-diastolic area (33.6% ± 6.2% vs 30.1% ± 9.7%; P = .03) and a trend toward better right ventricular function (55.5% ± 79.7% vs 35.7% ± 60.5%; P = .28) were noted in patients undergoing a concomitant tricuspid valve procedure. Survival was comparable between the 2 groups. In patients with severe tricuspid regurgitation undergoing left ventricular assist device implantation, a concomitant tricuspid valve procedure effectively reduces tricuspid regurgitation and promotes reverse remodeling of the right ventricle. Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.

  19. Spin injection and transport in semiconductor and metal nanostructures

    Science.gov (United States)

    Zhu, Lei

    In this thesis we investigate spin injection and transport in semiconductor and metal nanostructures. To overcome the limitation imposed by the low efficiency of spin injection and extraction and strict requirements for retention of spin polarization within the semiconductor, novel device structures with additional logic functionality and optimized device performance have been developed. Weak localization/antilocalization measurements and analysis are used to assess the influence of surface treatments on elastic, inelastic and spin-orbit scatterings during the electron transport within the two-dimensional electron layer at the InAs surface. Furthermore, we have used spin-valve and scanned probe microscopy measurements to investigate the influence of sulfur-based surface treatments and electrically insulating barrier layers on spin injection into, and spin transport within, the two-dimensional electron layer at the surface of p-type InAs. We also demonstrate and analyze a three-terminal, all-electrical spintronic switching device, combining charge current cancellation by appropriate device biasing and ballistic electron transport. The device yields a robust, electrically amplified spin-dependent current signal despite modest efficiency in electrical injection of spin-polarized electrons. Detailed analyses provide insight into the advantages of ballistic, as opposed to diffusive, transport in device operation, as well as scalability to smaller dimensions, and allow us to eliminate the possibility of phenomena unrelated to spin transport contributing to the observed device functionality. The influence of the device geometry on magnetoresistance of nanoscale spin-valve structures is also demonstrated and discussed. Shortcomings of the simplified one-dimensional spin diffusion model for spin valve are elucidated, with comparison of the thickness and the spin diffusion length in the nonmagnetic channel as the criterion for validity of the 1D model. Our work contributes

  20. Melanin: spin behaviour and implications for bioelectronic devices (Presentation Recording)

    Science.gov (United States)

    Meredith, Paul; Sheliakina, Margarita; Mostert, Bernard

    2015-10-01

    The melanins are a broad class of pigmentary macromolecules found through nature that perform a wide range of functions including photo-protection [1]. The most common melanin - the brown, black pigment eumelanin, has been much studied because of its role in melanoma and also for its functional material properties [2]. Synthetic eumelanin has been shown to be photoconductive in the solid state and also possess a water content dependent dark conductivity [3]. It is now well established that these electrical properties arise from hybrid ionic-electronic behaviour, leading to the proposition that melanins could be model biocompatible systems for ion-to-electron transduction in bioelectronics. In my talk, I will discuss the basic science behind these bioelectronics properties - electrical and optical. In this context I will also describe recent electron paramagnetic spin studies which isolate the role of the various chemical moieties responsible for the hybrid ionic-electronic behaviour. I will also highlight preliminary results on prototype melanin-based bioelectronics devices and discuss possible architectures to realise elements such as solid-state switches and transducers. [1] "The physical and chemical properties of eumelanin", P. Meredith and T. Sarna, Pigment Cell Research, 19(6), pp572-594 (2006). [2] "Electronic and optoelectronic materials and devices inspired by nature", P Meredith, C.J. Bettinger, M. Irimia-Vladu, A.B. Mostert and P.E. Schwenn, Reports on Progress in Physics, 76, 034501 (2013). [3] "Is melanin a semiconductor: humidity induced self doping and the electrical conductivity of a biopolymer", A.B. Mostert, B.J. Powell, F.L. Pratt, G.R. Hanson, T. Sarna, I.R. Gentle and P. Meredith, Proceedings of the National Academy of Sciences of the USA, 109(23), 8943-8947 (2012).

  1. A microfluidic device with multi-valves system to enable several simultaneous exposure tests on Caenorhabditis elegans

    International Nuclear Information System (INIS)

    Jung, Jaehoon; Masaru, Takeuchi; Nakajima, Masahiro; Huang, Qiang; Fukuda, Toshio

    2014-01-01

    In this paper, we report on a microfluidic device with a multi-valve system to conduct several exposure tests on Caenorhabditis elegans (C. elegans) simultaneously. It has pneumatic valves and no-moving-parts (NMP) valves. An NMP valve is incorporated with a chamber and enables the unidirectional movement of C. elegans in the chamber; once worms are loaded into the chamber, they cannot exit, regardless of the flow direction. To demonstrate the ability of the NMP valve to handle worms, we made a microfluidic device with three chambers. Each chamber was used to expose worms to Cd and Cu solutions, and K-medium. A pair of electrodes was installed in the device and the capacitance in-between the electrode was measured. When a C. elegans passed through the electrodes, the capacitance was changed. The capacitance change was proportional to the body volume of the worm, thus the body volume change by the heavy metal exposure was measured in the device. Thirty worms were divided into three groups and exposed to each solution. We confirmed that the different solutions induced differences in the capacitance changes for each group. These results indicate that our device is a viable method for simultaneously analyzing the effect of multiple stimuli on C. elegans. (paper)

  2. Spin-wave logic devices based on isotropic forward volume magnetostatic waves

    International Nuclear Information System (INIS)

    Klingler, S.; Pirro, P.; Brächer, T.; Leven, B.; Hillebrands, B.; Chumak, A. V.

    2015-01-01

    We propose the utilization of isotropic forward volume magnetostatic spin waves in modern wave-based logic devices and suggest a concrete design for a spin-wave majority gate operating with these waves. We demonstrate by numerical simulations that the proposed out-of-plane magnetized majority gate overcomes the limitations of anisotropic in-plane magnetized majority gates due to the high spin-wave transmission through the gate, which enables a reduced energy consumption of these devices. Moreover, the functionality of the out-of-plane majority gate is increased due to the lack of parasitic generation of short-wavelength exchange spin waves

  3. Spin-wave logic devices based on isotropic forward volume magnetostatic waves

    Energy Technology Data Exchange (ETDEWEB)

    Klingler, S., E-mail: stefan.klingler@wmi.badw-muenchen.de; Pirro, P.; Brächer, T.; Leven, B.; Hillebrands, B.; Chumak, A. V. [Fachbereich Physik and Landesforschungszentrum OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern (Germany)

    2015-05-25

    We propose the utilization of isotropic forward volume magnetostatic spin waves in modern wave-based logic devices and suggest a concrete design for a spin-wave majority gate operating with these waves. We demonstrate by numerical simulations that the proposed out-of-plane magnetized majority gate overcomes the limitations of anisotropic in-plane magnetized majority gates due to the high spin-wave transmission through the gate, which enables a reduced energy consumption of these devices. Moreover, the functionality of the out-of-plane majority gate is increased due to the lack of parasitic generation of short-wavelength exchange spin waves.

  4. Spin-filter scanning tunneling microscopy : a novel technique for the analysis of spin polarization on magnetic surfaces and spintronic devices

    NARCIS (Netherlands)

    Vera Marun, I.J.

    2010-01-01

    This thesis deals with the development of a versatile technique to measure spin polarization with atomic resolution. A microscopy technique that can measure electronic spin polarization is relevant for characterization of magnetic nanostructures and spintronic devices. Scanning tunneling microscopy

  5. Spin-dependent tunneling transport into CrO2 nanorod devices with nonmagnetic contacts.

    Science.gov (United States)

    Song, Yipu; Schmitt, Andrew L; Jin, Song

    2008-08-01

    Single-crystal nanorods of half-metallic chromium dioxide (CrO2) were synthesized and structurally characterized. Spin-dependent electrical transport was investigated in individual CrO2 nanorod devices contacted with nonmagnetic metallic electrodes. Negative magnetoresistance (MR) was observed at low temperatures due to the spin-dependent direct tunneling through the contact barrier and the high spin polarization in the half-metallic nanorods. The magnitude of this negative magnetoresistance decreases with increasing bias voltage and temperature due to spin-independent inelastic hopping through the barrier, and a small positive magnetoresistance was found at room temperature. It is believed that the contact barrier and the surface state of the nanorods have great influence on the spin-dependent transport limiting the magnitude of MR effect in this first attempt at spin filter devices of CrO2 nanorods with nonmagnetic contacts.

  6. Spin Hall conductance in a Y-shaped junction device in presence of tunable spin-orbit coupling

    Science.gov (United States)

    Ganguly, Sudin; Basu, Saurabh

    2017-06-01

    We study spin Hall effect in a three terminal Y-shaped device in presence of tunable spin-orbit (SO) interactions via Landauer-Büttiker formalism. We have evolved a fabrication technique for creating different angular separation between the two arms of the Y-shaped device so as to investigate the effect of angular width on the spin Hall conductance (SHC). A smaller angular separation yields a larger conductance. Also arbitrary orientation of the spin quantization axes yields interesting three dimensional contour maps for the SHC corresponding to different angular separation of the Y-shaped device. In addition to the GSH demonstrating bounded behaviour for different angular separations, there are distinct symmetry axes about which SHC demonstrates reflection symmetry. The results explicitly show breaking of the spin rotational symmetry. Further a systematic study is carried out to compare and contrast between the different SO terms, such as Rashba and Dresselhaus SO interactions and the interplay of the angular separation therein.

  7. Verification of the Thomson-Onsager reciprocity relation for spin caloritronics

    NARCIS (Netherlands)

    Dejene, F. K.; Flipse, J.; van Wees, B. J.

    2014-01-01

    We investigate the Thomson-Onsager relation between the spin-dependent Seebeck and spin-dependent Peltier effect. To maintain identical device and measurement conditions we measure both effects in a single Ni80Fe20/Cu/Ni80Fe20 nanopillar spin valve device subjected to either an electrical or a

  8. Repeat transcatheter aortic valve implantation using a latest generation balloon-expandable device for treatment of failing transcatheter heart valves.

    Science.gov (United States)

    Schaefer, Andreas; Treede, Hendrik; Seiffert, Moritz; Deuschl, Florian; Schofer, Niklas; Schneeberger, Yvonne; Blankenberg, Stefan; Reichenspurner, Hermann; Schaefer, Ulrich; Conradi, Lenard

    2016-01-15

    Paravalvular leakage (PVL) is a known complication of transcatheter aortic valve implantation (TAVI) and is associated with poor outcome. Besides balloon-post-dilatation, valve-in-valve (ViV) procedures can be taken into consideration to control this complication. Herein we present initial experience with use of the latest generation balloon-expandable Edwards Sapien 3® (S3) transcatheter heart valve (THV) for treatment of failing THVs. Between 01/2014 and 12/2014 three patients (two male, age: 71-80 y, log EUROScore I: 11.89 - 32.63) with failing THVs were refered to our institution for further treatment. THV approach with secondary implantation of an S3 was chosen after mutual agreement of the local interdisciplinary heart team at an interval of 533-1119 days from the index procedure. The performed procedures consisted of: S3 in Sapien XT, JenaValve and CoreValve. Successful transfemoral implantation with significant reduction of PVL was achieved in all cases. No intraprocedural complications occurred regarding placement of the S3 with a postprocedural effective orifice area (EOA) of 1.5-2.5 cm(2) and pressure gradients of max/mean 14/6-36/16 mmHg. 30-day mortality was 0%. At the latest follow-up of 90-530 days, all patients are alive and well with satisfactory THV function. Regarding VARC-2 criteria one major bleeding and one TIA was reported. In the instance of moderate or severe aortic regurgitation after TAVI, S3 ViV deployment is an excellent option to reduce residual regurgitation to none or mild. For further assertions concerning functional outcomes long-term results have to be awaited.

  9. Superconducting spin valves based on epitaxial Fe/V-hybrid thin film heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Nowak, Gregor

    2010-12-10

    This study presents a systematic investigation of the SSV effect in FM/SC/FM and FM/N/FM/SC heterostructures. Before investigating the actual SSV effect, we first pre-analyzed structural, magnetic and superconducting properties of the Fe/V system. In these preliminary studies we demonstrated, that epitaxial Fe/V heterostructures of superior crystalline quality can be grown by DC sputter deposition. With a Fe/V interface thickness of only one monolayer, the chemical separation of the Fe and V layers is extremely sharp. Moreover, the magnetic investigation showed that from thicknesses of two Fe(001) monolayers on the Fe layers in the superlattice possess a magnetic moment. Furthermore, we demonstrated the interlayer exchange coupling as oscillatory function of the V interlayer thickness. The investigations of the superconducting parameters of the Fe/V system revealed a non-monotonic T{sub S} vs. d{sub Fe} dependence in sample series (1). This observation proves the presence of the FM/SC proximity effect. The studies of various heterostructures of the design AFM/FM/SC/FM revealed a strong counteracting influence on the SSV effect, the stray field effect. The sample containing Fe{sub 25}V{sub 75} alloy layers, has the highest ratio of Cooper pair coherence length and superconductor thickness (ξ{sub S})/(d{sub S}), and its superconducting transition temperature is comparable to the sample with Fe{sub 35}V{sub 65} alloy layers. Nevertheless, the SSV effect in sample Fe{sub 25}V{sub 75} with alloy layers is much smaller than in sample with Fe{sub 35}V{sub 65} alloy layers. For a high-performance superconducting spin valve based on a FM1/SC/FM2 heterostructure at least four parameters have to be optimized simultaneously. 1. The magnetic domain size in FM1 and FM2 has to be as large as possible in order to reduce the stray field effect resulting from magnetization components in the FM domain walls perpendicular to the SC layer. 2. When using ferromagnetic alloys as

  10. Spin-dependent transport and functional design in organic ferromagnetic devices

    Directory of Open Access Journals (Sweden)

    Guichao Hu

    2017-09-01

    Full Text Available Organic ferromagnets are intriguing materials in that they combine ferromagnetic and organic properties. Although challenges in their synthesis still remain, the development of organic spintronics has triggered strong interest in high-performance organic ferromagnetic devices. This review first introduces our theory for spin-dependent electron transport through organic ferromagnetic devices, which combines an extended Su–Schrieffer–Heeger model with the Green’s function method. The effects of the intrinsic interactions in the organic ferromagnets, including strong electron–lattice interaction and spin–spin correlation between π-electrons and radicals, are highlighted. Several interesting functional designs of organic ferromagnetic devices are discussed, specifically the concepts of a spin filter, multi-state magnetoresistance, and spin-current rectification. The mechanism of each phenomenon is explained by transmission and orbital analysis. These works show that organic ferromagnets are promising components for spintronic devices that deserve to be designed and examined in future experiments.

  11. Low permanent pacemaker rates following Lotus device implantation for transcatheter aortic valve replacement due to modified implantation protocol.

    Science.gov (United States)

    Krackhardt, Florian; Kherad, Behrouz; Krisper, Maximilian; Pieske, Burkert; Laule, Michael; Tschöpe, Carsten

    2017-01-01

    Conduction disturbances requiring permanent pacemaker implantation following transcatheter aortic valve replacement (TAVR) are a common problem. Pacemaker implantation rates after TAVR appear to be higher compared to conventional aortic valve replacement. The aim of this study was to analyze whether a high annulus implantation conveys the benefit of a decreased rate of permanent pacemaker implantation while being safe and successful according to Valve Academic Research Consortium 2 (VARC2)-criteria. A total of 23 patients with symptomatic severe aortic valve stenosis, an aortic annulus of 19-27 mm and at high risk for surgery were treated with the Lotus valve. In all patients the valve was implanted in a high annulus position via femoral access. The primary device performance endpoint was VARC2-defined device success after 30 days and the primary safety endpoint was the need for permanent pacemaker implantation. The mean age was 73.23 ± 7.65 years, 46% were female, 38% were New York Heart Association class III/IV at baseline. Thirty-day follow-up data were available for all patients. The VARC2-defined device success rate after 30 days was 22/23 (96%). 2/21 (10%) patients required a newly implanted pacemaker due to 3rd degree atrioventricular block. 25% of the patients developed a new left bundle branch block after valvuloplasty or device implantation. 21 of the 23 patients (96%) had no other signs of conduction disturbances after 30 days. The approach of the modified implantation technique of Lotus TAVR device was safe and effective. The incidence of need for a permanent pacemaker following TAVR could be significantly reduced due to adopted implantation protocol.

  12. Spin Transfer Torque in Graphene

    Science.gov (United States)

    Lin, Chia-Ching; Chen, Zhihong

    2014-03-01

    Graphene is an idea channel material for spin transport due to its long spin diffusion length. To develop graphene based spin logic, it is important to demonstrate spin transfer torque in graphene. Here, we report the experimental measurement of spin transfer torque in graphene nonlocal spin valve devices. Assisted by a small external in-plane magnetic field, the magnetization reversal of the receiving magnet is induced by pure spin diffusion currents from the injector magnet. The magnetization switching is reversible between parallel and antiparallel configurations by controlling the polarity of the applied charged currents. Current induced heating and Oersted field from the nonlocal charge flow have also been excluded in this study. Next, we further enhance the spin angular momentum absorption at the interface of the receiving magnet and graphene channel by removing the tunneling barrier in the receiving magnet. The device with a tunneling barrier only at the injector magnet shows a comparable nonlocal spin valve signal but lower electrical noise. Moreover, in the same preset condition, the critical charge current density for spin torque in the single tunneling barrier device shows a substantial reduction if compared to the double tunneling barrier device.

  13. Biomolecule detection using wheatstone bridge giant magnetoresistance (GMR) sensors based on CoFeB spin-valve thin film

    Science.gov (United States)

    Elda Swastika, P.; Antarnusa, G.; Suharyadi, E.; Kato, T.; Iwata, S.

    2018-04-01

    A potential wheatstone bridge giant magnetoresistance (GMR) biosensor have been successfully developed for biomolecule detection. [IrMn(10 nm)/CoFe(3 nm)/Cu(2.2 nm)/CoFeB(10 nm)] spin-valve structure has been chosen as the magnetic sensing surface, showing a magnetoresistance (MR) of 6% fabricated by DC magnetron sputtering method. The Fe3O4 magnetic nanoparticles used as biomolecular labels (nanotags) was synthesized by co-precipitation method, exhibiting soft magnetic behavior with saturation magnetization (Ms), remanent magnetization (Mr) and coercivity (Hc) is 77.2 emu/g, 7.8 emu/g and 51 Oe, respectively. The X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) images showed that Fe3O4 was well crystallized and grew in their inverse spinel structure, highly uniform morphology with an average grain size was about 20 nm. Fe3O4 was coated with polyethylene-glycol (PEG)-4000 for surface functionalization. Detection of biomolecule such as formalin, gelatin from bovine-skin and porcine-skin were dispersed in ethanol at room temperature. Induction would cause a shift in output voltage with a minimum delta output voltage (ΔV) 4.937 mV (10%) for formalin detection, 2.268 mV (7%) for bovine-skin gelatin and 2.943 mV (7%) for porcine-skin gelatin detection. The ΔV of the wheatstone bridge in real-time measurement decrease by increase in biomolecules concentration. The change of ΔV with various concentration of biomolecule indicates that the spin-valve thin film with wheatstone-bridge circuit is potential as a biosensor.

  14. Fabrication of magnetic tunnel junctions connected through a continuous free layer to enable spin logic devices

    Science.gov (United States)

    Wan, Danny; Manfrini, Mauricio; Vaysset, Adrien; Souriau, Laurent; Wouters, Lennaert; Thiam, Arame; Raymenants, Eline; Sayan, Safak; Jussot, Julien; Swerts, Johan; Couet, Sebastien; Rassoul, Nouredine; Babaei Gavan, Khashayar; Paredis, Kristof; Huyghebaert, Cedric; Ercken, Monique; Wilson, Christopher J.; Mocuta, Dan; Radu, Iuliana P.

    2018-04-01

    Magnetic tunnel junctions (MTJs) interconnected via a continuous ferromagnetic free layer were fabricated for spin torque majority gate (STMG) logic. The MTJs are biased independently and show magnetoelectric response under spin transfer torque. The electrical control of these devices paves the way to future spin logic devices based on domain wall (DW) motion. In particular, it is a significant step towards the realization of a majority gate. To our knowledge, this is the first fabrication of a cross-shaped free layer shared by several perpendicular MTJs. The fabrication process can be generalized to any geometry and any number of MTJs. Thus, this framework can be applied to other spin logic concepts based on magnetic interconnect. Moreover, it allows exploration of spin dynamics for logic applications.

  15. In situ scanning tunneling microscope tip treatment device for spin polarization imaging

    Science.gov (United States)

    Li, An-Ping [Oak Ridge, TN; Jianxing, Ma [Oak Ridge, TN; Shen, Jian [Knoxville, TN

    2008-04-22

    A tip treatment device for use in an ultrahigh vacuum in situ scanning tunneling microscope (STM). The device provides spin polarization functionality to new or existing variable temperature STM systems. The tip treatment device readily converts a conventional STM to a spin-polarized tip, and thereby converts a standard STM system into a spin-polarized STM system. The tip treatment device also has functions of tip cleaning and tip flashing a STM tip to high temperature (>2000.degree. C.) in an extremely localized fashion. Tip coating functions can also be carried out, providing the tip sharp end with monolayers of coating materials including magnetic films. The device is also fully compatible with ultrahigh vacuum sample transfer setups.

  16. Towards sub-200 nm nano-structuring of linear giant magneto-resistive spin valves by a direct focused ion beam milling process

    International Nuclear Information System (INIS)

    Riedmüller, Benjamin; Huber, Felix; Herr, Ulrich

    2014-01-01

    In this work, we present a detailed investigation of a focused ion beam (FIB) assisted nano-structuring process for giant magneto-resistive (GMR) spin valve sensors. We have performed a quantitative study of the dependence of the GMR ratio as well as the sensor resistance on the ion dose, which is implanted in the active region of our sensors. These findings are correlated with the decrease of magneto-resistive properties after micro- and nano-structuring by the FIB and reveal the importance of ion damage which limits the applicability of FIB milling to GMR devices in the low μm range. Deposition of a protective layer (50 nm SiO 2 ) on top of the sensor structure before milling leads to a preservation of the magneto-resistive properties after the milling procedure down to sensor dimensions of ∼300 nm. The reduction of the sensor dimensions to the nanometer regime is accompanied by a shift of the GMR curves, and a modification of the saturation behavior. Both effects can be explained by a micromagnetic model including the magnetic interaction of free and pinned layer as well as the effect of the demagnetizing field of the free layer on the sensor behavior. The results demonstrate that the FIB technology can be successfully used to prepare spintronic nanostructures

  17. Minimally Invasive Implantation of HeartWare Assist Device and Simultaneous Tricuspid Valve Reconstruction Through Partial Upper Sternotomy.

    Science.gov (United States)

    Hillebrand, Julia; Hoffmeier, Andreas; Djie Tiong Tjan, Tonny; Sindermann, Juergen R; Schmidt, Christoph; Martens, Sven; Scherer, Mirela

    2017-05-01

    Left ventricular assist device (LVAD) implantation is a well-established therapy to support patients with end-stage heart failure. However, the operative procedure is associated with severe trauma. Third generation LVADs like the HeartWare assist device (HeartWare, Inc., Framingham, MA, USA) are characterized by enhanced technology despite smaller size. These devices offer new minimally invasive surgical options. Tricuspid regurgitation requiring valve repair is frequent in patients with the need for mechanical circulatory support as it is strongly associated with ischemic and nonischemic cardiomyopathy. We report on HeartWare LVAD implantation and simultaneous tricuspid valve reconstruction through minimally invasive access by partial upper sternotomy to the fifth left intercostal space. Four male patients (mean age 51.72 ± 11.95 years) suffering from chronic heart failure due to dilative (three patients) and ischemic (one patient) cardiomyopathy and also exhibiting concomitant tricuspid valve insufficiency due to annular dilation underwent VAD implantation and tricuspid valve annuloplasty. Extracorporeal circulation was established via the ascending aorta, superior vena cava, and right atrium. In all four cases the LVAD implantation and tricuspid valve repair via partial median sternotomy was successful. During the operative procedure, no conversion to full sternotomy was necessary. One patient needed postoperative re-exploration because of pericardial effusion. No postoperative focal neurologic injury was observed. New generation VADs are advantageous because of the possibility of minimally invasive implantation procedure which can therefore minimize surgical trauma. Concomitant tricuspid valve reconstruction can also be performed simultaneously through partial upper sternotomy. Nevertheless, minimally invasive LVAD implantation is a challenging operative technique. © 2016 International Center for Artificial Organs and Transplantation and Wiley Periodicals

  18. Quantum interference effect in electron tunneling through a quantum-dot-ring spin valve.

    Science.gov (United States)

    Ma, Jing-Min; Zhao, Jia; Zhang, Kai-Cheng; Peng, Ya-Jing; Chi, Feng

    2011-03-28

    Spin-dependent transport through a quantum-dot (QD) ring coupled to ferromagnetic leads with noncollinear magnetizations is studied theoretically. Tunneling current, current spin polarization and tunnel magnetoresistance (TMR) as functions of the bias voltage and the direct coupling strength between the two leads are analyzed by the nonequilibrium Green's function technique. It is shown that the magnitudes of these quantities are sensitive to the relative angle between the leads' magnetic moments and the quantum interference effect originated from the inter-lead coupling. We pay particular attention on the Coulomb blockade regime and find the relative current magnitudes of different magnetization angles can be reversed by tuning the inter-lead coupling strength, resulting in sign change of the TMR. For large enough inter-lead coupling strength, the current spin polarizations for parallel and antiparallel magnetic configurations will approach to unit and zero, respectively.PACS numbers:

  19. Quantum interference effect in electron tunneling through a quantum-dot-ring spin valve

    Directory of Open Access Journals (Sweden)

    Ma Jing-Min

    2011-01-01

    Full Text Available Abstract Spin-dependent transport through a quantum-dot (QD ring coupled to ferromagnetic leads with noncollinear magnetizations is studied theoretically. Tunneling current, current spin polarization and tunnel magnetoresistance (TMR as functions of the bias voltage and the direct coupling strength between the two leads are analyzed by the nonequilibrium Green's function technique. It is shown that the magnitudes of these quantities are sensitive to the relative angle between the leads' magnetic moments and the quantum interference effect originated from the inter-lead coupling. We pay particular attention on the Coulomb blockade regime and find the relative current magnitudes of different magnetization angles can be reversed by tuning the inter-lead coupling strength, resulting in sign change of the TMR. For large enough inter-lead coupling strength, the current spin polarizations for parallel and antiparallel magnetic configurations will approach to unit and zero, respectively. PACS numbers:

  20. EXPERIENCES IN THE AIR SPINNING TO MANUFACTURE MEDICAL DEVICES

    Directory of Open Access Journals (Sweden)

    MARSAL Feliu

    2015-05-01

    Full Text Available The work aims to determine, with scientific rigor, differences in key parameters of the yarns produced by conventional ring spinning systems, open-end and air spinning and its interrelation with the main parameters of those products that are intended for medical-sanitary sector. The experiences have been made in a Spanish company from short fibers sector that has three spinning systems, with tradition and prestige in world market, validating the results in Innotex Center laboratories of the Polytechnic University of Catalonia. Considering the results, it shows that the technology of manufacture of yarns by air is suitable for yarn, woven fabrics and knitting, structures to textile medical-sanitary application, by specific properties as well as enhanced competitiveness, due to the high production rate and shortened spinning process. The viscose yarns manufactured by air mass are more mass regular. The new DR parameter clearly indicates a better look of the finished fabric when we work with yarns produced by air technology.The significant reduction of the hairiness means less formation of loose fibres by friction, very important in the application of these yarns in the manufacture of textile structures for medical-sanitary use. Also no-table increase of about 15% in the absorption capacity of the fluids, especially water, from the yarns made by air. In the functionalization of fabrics obtained from spun yarn by air will need to apply a permanent smoothing.

  1. Integrated nozzle - flapper valve with piezoelectric actuator and isothermal chamber: a feedback linearization multi control device

    Energy Technology Data Exchange (ETDEWEB)

    Kamali, Mohammadreza; Jazayeri, Seyed Ali [K. N.Toosi University of Technology, Tehran (Iran, Islamic Republic of); Najafi, Farid [University of Guilan, Rasht (Iran, Islamic Republic of); Kawashima, Kenji [Tokyo Medical and Dental University, Tokyo (Japan); Kagawa, Toshiharu [Tokyo Institute of Technology, Tokyo (Japan)

    2016-05-15

    This paper introduces a new nozzle-flapper valve with isothermal chamber using piezoelectric actuator. It controls the pressure and flow rate simply, effectively and separately. The proposed valve uses isothermal chamber presenting practical isothermal condition due to its large heat transfer interfaces filled by metal wool. The valve uses stacked type piezoelectric actuator with unique advantages. By using this valve, a simple method has been fulfilled to control flow rate or pressure of ideal gases in a pneumatic actuators. Experimental results demonstrated applications of the proposed valve to control either pressure or flow rate in pneumatic circuits. This valve can be also used in the pilot stage valve to actuate the main stage of a much bigger pneumatic valve. Designated structure contains only one pressure sensor installed on the isothermal control chamber, capable of controlling both pressure and flow rate. The desired output mass flow rate of the valve is controlled by the pressure changes during positioning of piezoelectric actuator at proper position. The proposed valve can control steady and unsteady oscillatory flow rate and pressure effectively, using nonlinear control method such as feedback linearization approach. Its effectiveness is demonstrated and validated through simulation and experiments.

  2. Nanosecond-timescale spin transfer using individual electrons in a quadruple-quantum-dot device

    Energy Technology Data Exchange (ETDEWEB)

    Baart, T. A.; Jovanovic, N.; Vandersypen, L. M. K. [QuTech and Kavli Institute of Nanoscience, Delft University of Technology, P.O. Box 5046, 2600 GA Delft (Netherlands); Reichl, C.; Wegscheider, W. [Solid State Physics Laboratory, ETH Zürich, 8093 Zürich (Switzerland)

    2016-07-25

    The ability to coherently transport electron-spin states between different sites of gate-defined semiconductor quantum dots is an essential ingredient for a quantum-dot-based quantum computer. Previous shuttles using electrostatic gating were too slow to move an electron within the spin dephasing time across an array. Here, we report a nanosecond-timescale spin transfer of individual electrons across a quadruple-quantum-dot device. Utilizing enhanced relaxation rates at a so-called hot spot, we can upper bound the shuttle time to at most 150 ns. While actual shuttle times are likely shorter, 150 ns is already fast enough to preserve spin coherence in, e.g., silicon based quantum dots. This work therefore realizes an important prerequisite for coherent spin transfer in quantum dot arrays.

  3. Dynamic detection of spin accumulation in ferromagnet-semiconductor devices by ferromagnetic resonance (Conference Presentation)

    Science.gov (United States)

    Crowell, Paul A.; Liu, Changjiang; Patel, Sahil; Peterson, Tim; Geppert, Chad C.; Christie, Kevin; Stecklein, Gordon; Palmstrøm, Chris J.

    2016-10-01

    A distinguishing feature of spin accumulation in ferromagnet-semiconductor devices is its precession in a magnetic field. This is the basis for detection techniques such as the Hanle effect, but these approaches become ineffective as the spin lifetime in the semiconductor decreases. For this reason, no electrical Hanle measurement has been demonstrated in GaAs at room temperature. We show here that by forcing the magnetization in the ferromagnet to precess at resonance instead of relying only on the Larmor precession of the spin accumulation in the semiconductor, an electrically generated spin accumulation can be detected up to 300 K. The injection bias and temperature dependence of the measured spin signal agree with those obtained using traditional methods. We further show that this new approach enables a measurement of short spin lifetimes (C. Liu, S. J. Patel, T. A. Peterson, C. C. Geppert, K. D. Christie, C. J. Palmstrøm, and P. A. Crowell, "Dynamic detection of electron spin accumulation in ferromagnet-semiconductor devices by ferromagnetic resonance," Nature Communications 7, 10296 (2016). http://dx.doi.org/10.1038/ncomms10296

  4. Spin dependent disorder in a junction device with spin orbit couplings

    International Nuclear Information System (INIS)

    Ganguly, Sudin; Basu, Saurabh

    2016-01-01

    Using the multi-probe Landauer-BUttiker formula and Green's function approach, we calculate the longitudinal conductance (LC) and spin Hall conductance (SHC) numerically in a two-dimensional junction system with the Rashba and Dresselhaus spin orbit coupling (SOC) and spin dependent disorder (SDD) in presence of both random onsite and hopping disorder strengths. It has been found that when the strengths of the RSOC and DSOC are same, the SHC vanishes. Further in presence of random onsite or hopping disorder, the SHC is still zero when the strengths of the two types of SOC, that is Rashba and Dressselhaus are the same. This indicates that the cancellation of SHC is robust even in the presence of random disorder. Only with the inclusion of SDD (onsite or hopping), a non-zero SHC is found and it increases as the strength of SDD increases. The physical implication of the existence of a non-zero SHC has been explored in this work. Finally, we have compared the effect of onsite SDD and hopping SDD on both longitudinal and spin Hall conductances. (paper)

  5. Magnetotransport in spin-valve systems with amorphous magnetic and superconducting partial layers; Magnetotransport in Spinventil-Systemen mit amorphen magnetischen und supraleitenden Teilschichten

    Energy Technology Data Exchange (ETDEWEB)

    Steiner, Roland Johannes

    2006-04-27

    The first part of this work deals with the fabrication and characterisation of spin valves with an amorphous FeB layer acting as a weak ferromagnet embedded into the structure. In the second part of this work ferromagnet/superconductor hybrid structures are fabricated and the relevant magnetic field dependent transport phenomena are analyzed. The interlayer of a conventional spin valve was replaced by a superconducting niobium layer. Small applied fields close to the coercivity field of the involved ferromagnets - and thus far below the critical magnetic field of the superconductor - affected the critical temperature of the niobium layer. Measurements of the field dependent resistance and the critical temperature of a FM/SC/FMsystem showed a local maximum in the T{sub c}(H)- and the R(H)-curve. (orig.)

  6. Interfacial spectroscopic characterization of organic/ferromagnet hetero-junction of 3,4,9,10-perylene-teracarboxylic dianhydride-based organic spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Hong, Jhen-Yong; Ou Yang, Kui-Hon; Li, Kai-Shin [Department of Physics, National Taiwan University, 10617 Taipei, Taiwan (China); Wang, Bo-Yao [Department of Physics, National Taiwan University, 10617 Taipei, Taiwan (China); Department of Physics, National Changhua University of Education, Changhua 500, Taiwan (China); Shiu, Hung-Wei; Chen, Chia-Hao; Chan, Yuet-Loy; Wei, Der-Hsin; Chang, Fan-Hsiu; Lin, Hong-Ji [National Synchrotron Radiation Research Center, 30076 Hsinchu, Taiwan (China); Chiang, Wen-Chung, E-mail: wchiang@faculty.pccu.edu.tw [Department of Physics, Chinese Culture University, 11114 Taipei, Taiwan (China); Lin, Minn-Tsong, E-mail: mtlin@phys.ntu.edu.tw [Department of Physics, National Taiwan University, 10617 Taipei, Taiwan (China); Institute of Atomic and Molecular Sciences, Academia Sinica, 10617 Taipei, Taiwan (China)

    2014-02-24

    We report interfacial characterization of 3,4,9,10-perylene-teracarboxylic dianhydride (PTCDA)-based organic spin valves (OSV) dusted with a thin layer of partially oxidized alumina at the organic semiconductor (OSC)/ferromagnet (FM) interfaces. Up to 13.5% magnetoresistance is achieved at room temperature. X-ray photoelectron spectroscopy measurements reveal interfacial electronic interaction between PTCDA and FM while the application of a thin alumina layer at the PTCDA/FM interfaces prevents the electronic hybridization and effectively preserves the spin injection into the OSC spacer. This finding demonstrates the critical effect of interfacial structure on magnetotransport behavior in OSV.

  7. Towards real-time cardiovascular magnetic resonance-guided transarterial aortic valve implantation: In vitro evaluation and modification of existing devices

    Directory of Open Access Journals (Sweden)

    Ladd Mark E

    2010-10-01

    Full Text Available Abstract Background Cardiovascular magnetic resonance (CMR is considered an attractive alternative for guiding transarterial aortic valve implantation (TAVI featuring unlimited scan plane orientation and unsurpassed soft-tissue contrast with simultaneous device visualization. We sought to evaluate the CMR characteristics of both currently commercially available transcatheter heart valves (Edwards SAPIEN™, Medtronic CoreValve® including their dedicated delivery devices and of a custom-built, CMR-compatible delivery device for the Medtronic CoreValve® prosthesis as an initial step towards real-time CMR-guided TAVI. Methods The devices were systematically examined in phantom models on a 1.5-Tesla scanner using high-resolution T1-weighted 3D FLASH, real-time TrueFISP and flow-sensitive phase-contrast sequences. Images were analyzed for device visualization quality, device-related susceptibility artifacts, and radiofrequency signal shielding. Results CMR revealed major susceptibility artifacts for the two commercial delivery devices caused by considerable metal braiding and precluding in vivo application. The stainless steel-based Edwards SAPIEN™ prosthesis was also regarded not suitable for CMR-guided TAVI due to susceptibility artifacts exceeding the valve's dimensions and hindering an exact placement. In contrast, the nitinol-based Medtronic CoreValve® prosthesis was excellently visualized with delineation even of small details and, thus, regarded suitable for CMR-guided TAVI, particularly since reengineering of its delivery device toward CMR-compatibility resulted in artifact elimination and excellent visualization during catheter movement and valve deployment on real-time TrueFISP imaging. Reliable flow measurements could be performed for both stent-valves after deployment using phase-contrast sequences. Conclusions The present study shows that the Medtronic CoreValve® prosthesis is potentially suited for real-time CMR-guided placement

  8. Role of radionuclide imaging for diagnosis of device and prosthetic valve infections

    Science.gov (United States)

    Sarrazin, Jean-François; Philippon, François; Trottier, Mikaël; Tessier, Michel

    2016-01-01

    Cardiovascular implantable electronic device (CIED) infection and prosthetic valve endocarditis (PVE) remain a diagnostic challenge. Cardiac imaging plays an important role in the diagnosis and management of patients with CIED infection or PVE. Over the past few years, cardiac radionuclide imaging has gained a key role in the diagnosis of these patients, and in assessing the need for surgery, mainly in the most difficult cases. Both 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) and radiolabelled white blood cell single-photon emission computed tomography/computed tomography (WBC SPECT/CT) have been studied in these situations. In their 2015 guidelines for the management of infective endocarditis, the European Society of Cardiology incorporated cardiac nuclear imaging as part of their diagnostic algorithm for PVE, but not CIED infection since the data were judged insufficient at the moment. This article reviews the actual knowledge and recent studies on the use of 18F-FDG PET/CT and WBC SPECT/CT in the context of CIED infection and PVE, and describes the technical aspects of cardiac radionuclide imaging. It also discusses their accepted and potential indications for the diagnosis and management of CIED infection and PVE, the limitations of these tests, and potential areas of future research. PMID:27721936

  9. Effect of nano-oxide layers on giant magnetoresistance in pseudo-spin-valves using Co2FeAl electrodes

    International Nuclear Information System (INIS)

    Zhang, D.L.; Xu, X.G.; Wu, Y.; Miao, J.; Jiang, Y.

    2011-01-01

    We studied the pseudo-spin-valves (PSVs) with a structure of Ta/Co 2 FeAl/NOL 1 /Co 2 FeAl/Cu/Co 2 FeAl/NOL 2 /Ta, where NOL represents the nano-oxide layer. Compared with the normal Co 2 FeAl (CFA) PSV with a structure of Ta/Co 2 FeAl/Cu/Co 2 FeAl/Ta, which shows only a current-in-plane (CIP) giant magnetoresistance (GMR) of 0.03%, the CFA PSV with NOLs shows a large CIP-GMR of 5.84%. The enhanced GMR by the NOLs inserted in the CFA PSV is due to the large specular reflection caused by [(CoO)(Fe 2 O 3 )(Al 2 O 3 )] in NOL 1 and [(Fe 2 O 3 )(Al 2 O 3 )(Ta 2 O 5 )] in NOL 2 . Another reason is that the roughness of the interface between Ta and CFA is improved by the oxidation procedure. - Research highlights: → Nano-oxide layers are applied in the pseudo-spin-valves with the Heusler alloy. → The CIP-GMR of pseudo-spin-valves is improved from 0.03% to 5.84%. → The GMR ratio is decided by the position of nano-oxide layers.

  10. Electrical detection of proton-spin motion in a polymer device at room temperature

    Science.gov (United States)

    Boehme, Christoph

    With the emergence of spintronics concepts based on organic semiconductors there has been renewed interest in the role of both, electron as well as nuclear spin states for the magneto-optoelectronic properties of these materials. In spite of decades of research on these molecular systems, there is still much need for an understanding of some of the fundamental properties of spin-controlled charge carrier transport and recombination processes. This presentation focuses on mechanisms that allow proton spin states to influence electronic transition rates in organic semiconductors. Remarkably, even at low-magnetic field conditions and room temperature, nuclear spin states with energy splittings orders of magnitude below thermal energies are able to influence observables like magnetoresistance and fluorescence. While proton spins couple to charge carrier spins via hyperfine interaction, there has been considerable debate about the nature of the electronic processes that are highly susceptible to these weak hyperfine fields. Here, experiments are presented which show how the magnetic resonant manipulation of electron and nuclear spin states in a π-conjugated polymer device causes changes of the device current. The experiments confirm the extraordinary sensitivity of electronic transitions to very weak magnetic field changes and underscore the potential significance of spin-selection rules for highly sensitive absolute magnetic fields sensor concepts. However, the relevance of these magnetic-field sensitive spin-dependent electron transitions is not just limited to semiconductor materials but also radical pair chemistry and even avian magnetoreceptors This work was supported by the US Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award #DE-SC0000909. The Utah NSF - MRSEC program #DMR 1121252 is acknowledged for instrumentation support.

  11. Integration of continuous-flow sampling with microchip electrophoresis using poly(dimethylsiloxane)-based valves in a reversibly sealed device.

    Science.gov (United States)

    Li, Michelle W; Martin, R Scott

    2007-07-01

    Here we describe a reversibly sealed microchip device that incorporates poly(dimethylsiloxane) (PDMS)-based valves for the rapid injection of analytes from a continuously flowing stream into a channel network for analysis with microchip electrophoresis. The microchip was reversibly sealed to a PDMS-coated glass substrate and microbore tubing was used for the introduction of gas and fluids to the microchip device. Two pneumatic valves were incorporated into the design and actuated on the order of hundreds of milliseconds, allowing analyte from a continuously flowing sampling stream to be injected into an electrophoresis separation channel. The device was characterized in terms of the valve actuation time and pushback voltage. It was also found that the addition of sodium dodecyl sulfate (SDS) to the buffer system greatly increased the reproducibility of the injection scheme and enabled the analysis of amino acids derivatized with naphthalene-2,3-dicarboxaldehyde/cyanide. Results from continuous injections of a 0.39 nL fluorescein plug into the optimized system showed that the injection process was reproducible (RSD of 0.7%, n = 10). Studies also showed that the device was capable of monitoring off-chip changes in concentration with a device lag time of 90 s. Finally, the ability of the device to rapidly monitor on-chip concentration changes was demonstrated by continually sampling from an analyte plug that was derivatized upstream from the electrophoresis/continuous flow interface. A reversibly sealed device of this type will be useful for the continuous monitoring and analysis of processes that occur either off-chip (such as microdialysis sampling) or on-chip from other integrated functions.

  12. Interplay between interface structure and magnetism in NiFe/Cu/Ni-based pseudo-spin valves

    Science.gov (United States)

    Loving, Melissa G.; Ambrose, Thomas F.; Ermer, Henry; Miller, Don; Naaman, Ofer

    2018-05-01

    Magnetic pseudo spin valves (PSVs) with superconducting Nb electrodes, have been leading candidates for an energy-efficient memory solution compatible with cryogenic operation of ultra-low power superconducting logic. Integration of these PSV Josephson junctions in a standard multi-layer Nb process requires growing high-quality thin magnetic films on a thick Nb bottom electrode (i.e. ≥1.5kÅ, to achieve bulk superconducting properties). However, as deposited, 1.5kÅ Nb exhibits a rough surface with a characteristic rice grain morphology, which severely degrades the switching properties of subsequently deposited PSVs. Therefore, in order to achieve coherent switching throughout a PSV, the Nb interface must be modified. Here, we demonstrate that the Nb surface morphology and PSV crystallinity can be altered with the incorporation of separate 50Å Cu or 100Å Al/50Å Cu non-magnetic seed layers, and demonstrate their impact on the magnetic switching of a 15Å Ni80Fe20/50Å Cu/20Å Ni PSV, at both room temperature and at 10 K. Most notably, these results show that the incorporation of an Al seed layer leads to an improved face centered cubic templating through the bulk of the PSV, and ultimately to superior magnetic switching.

  13. Significant manipulation of output performance of a bridge-structured spin valve magnetoresistance sensor via an electric field

    Science.gov (United States)

    Zhang, Yue; Yan, Baiqian; Ou-Yang, Jun; Wang, Xianghao; Zhu, Benpeng; Chen, Shi; Yang, Xiaofei

    2016-01-01

    Through principles of spin-valve giant magnetoresistance (SV-GMR) effect and its application in magnetic sensors, we have investigated electric-field control of the output performance of a bridge-structured Co/Cu/NiFe/IrMn SV-GMR sensor on a PZN-PT piezoelectric substrate using the micro-magnetic simulation. We centered on the influence of the variation of uniaxial magnetic anisotropy constant (K) of Co on the output of the bridge, and K was manipulated via the stress of Co, which is generated from the strain of a piezoelectric substrate under an electric field. The results indicate that when K varies between 2 × 104 J/m3 and 10 × 104 J/m3, the output performance can be significantly manipulated: The linear range alters from between -330 Oe and 330 Oe to between -650 Oe and 650 Oe, and the sensitivity is tuned by almost 7 times, making it possible to measure magnetic fields with very different ranges. According to the converse piezoelectric effect, we have found that this variation of K can be realized by applying an electric field with the magnitude of about 2-20 kV/cm on a PZN-PT piezoelectric substrate, which is realistic in application. This result means that electric-control of SV-GMR effect has potential application in developing SV-GMR sensors with improved performance.

  14. Microfluidic sieve valves

    Science.gov (United States)

    Quake, Stephen R; Marcus, Joshua S; Hansen, Carl L

    2015-01-13

    Sieve valves for use in microfluidic device are provided. The valves are useful for impeding the flow of particles, such as chromatography beads or cells, in a microfluidic channel while allowing liquid solution to pass through the valve. The valves find particular use in making microfluidic chromatography modules.

  15. Electron spin for classical information processing: a brief survey of spin-based logic devices, gates and circuits

    International Nuclear Information System (INIS)

    Bandyopadhyay, Supriyo; Cahay, Marc

    2009-01-01

    In electronics, information has been traditionally stored, processed and communicated using an electron's charge. This paradigm is increasingly turning out to be energy-inefficient, because movement of charge within an information processing device invariably causes current flow and an associated dissipation. Replacing 'charge' with the 'spin' of an electron to encode information may eliminate much of this dissipation and lead to more energy-efficient 'green electronics'. This realization has spurred significant research in spintronic devices and circuits where spin either directly acts as the physical variable for hosting information or augments the role of charge. In this review article, we discuss and elucidate some of these ideas, and highlight their strengths and weaknesses. Many of them can potentially reduce energy dissipation significantly, but unfortunately are error-prone and unreliable. Moreover, there are serious obstacles to their technological implementation that may be difficult to overcome in the near term. This review addresses three constructs: (1) single devices or binary switches that can be constituents of Boolean logic gates for digital information processing, (2) complete gates that are capable of performing specific Boolean logic operations, and (3) combinational circuits or architectures (equivalent to many gates working in unison) that are capable of performing universal computation. (topical review)

  16. A spin-valve-like magnetoresistance of an antiferromagnet-based tunnel junction

    Czech Academy of Sciences Publication Activity Database

    Park, B.G.; Wunderlich, Joerg; Martí, X.; Holý, V.; Kurosaki, Y.; Yamada, M.; Yamamoto, H.; Nishide, A.; Hayakawa, J.; Takahashi, H.; Shick, Alexander; Jungwirth, Tomáš

    2011-01-01

    Roč. 10, č. 5 (2011), s. 347-351 ISSN 1476-1122 R&D Projects: GA AV ČR KAN400100652; GA MŠk LC510; GA MŠk(CZ) 7E08087 EU Projects: European Commission(XE) 268066 - 0MSPIN; European Commission(XE) 214499 - NAMASTE; European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521; CEZ:AV0Z10100520 Keywords : spintronics * antiferromagnets Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 32.841, year: 2011

  17. Quantum interference measurement of spin interactions in a bio-organic/semiconductor device structure

    Science.gov (United States)

    Deo, Vincent; Zhang, Yao; Soghomonian, Victoria; Heremans, Jean J.

    2015-03-01

    Quantum interference is used to measure the spin interactions between an InAs surface electron system and the iron center in the biomolecule hemin in nanometer proximity in a bio-organic/semiconductor device structure. The interference quantifies the influence of hemin on the spin decoherence properties of the surface electrons. The decoherence times of the electrons serve to characterize the biomolecule, in an electronic complement to the use of spin decoherence times in magnetic resonance. Hemin, prototypical for the heme group in hemoglobin, is used to demonstrate the method, as a representative biomolecule where the spin state of a metal ion affects biological functions. The electronic determination of spin decoherence properties relies on the quantum correction of antilocalization, a result of quantum interference in the electron system. Spin-flip scattering is found to increase with temperature due to hemin, signifying a spin exchange between the iron center and the electrons, thus implying interactions between a biomolecule and a solid-state system in the hemin/InAs hybrid structure. The results also indicate the feasibility of artificial bioinspired materials using tunable carrier systems to mediate interactions between biological entities.

  18. Element-specific ferromagnetic resonance in epitaxial Heusler spin valve systems

    Energy Technology Data Exchange (ETDEWEB)

    Klaer, P; Jorge, E Arbelo; Jourdan, M; Elmers, H J [Institut fuer Physik, Johannes Gutenberg-Universitaet Mainz, D-55128 Mainz (Germany); Hoffmann, F; Woltersdorf, G; Back, C H, E-mail: elmers@uni-mainz.de [Institut fuer Experimentelle und Angewandte Physik, Universitaet Regensburg, D-93040 Regensburg (Germany)

    2011-10-26

    Time-resolved x-ray magnetic circular dichroism was used to investigate epitaxial MgO(100)/Co{sub 2}Cr{sub 0.6}Fe{sub 0.4}Al and MgO(100)/Co{sub 2}Cr{sub 0.6}Fe{sub 0.4}Al/Cr/CoFe films. The precessional motion of the individual sublattice magnetization, excited by continuous microwave excitation in the range 2-10 GHz, was detected by tuning the x-ray photon energy to the L{sub 3} absorption edges of Cr, Fe and Co. The relative phase angle of the sublattice magnetization's response is smaller than the detection limit of 2{sup 0}. A weakly antiferromagnetically coupled CoFe layer causes an increase in the ferromagnetic resonance linewidth consisting of a constant offset and a component linearly increasing with frequency that we partly attribute to non-local damping due to spin pumping.

  19. Steps toward an all-electric spin valve using side-gated quantum point contacts with lateral spin–orbit coupling

    International Nuclear Information System (INIS)

    Bhandari, Nikhil; Dutta, Maitreya; Charles, James; Cahay, Marc; Newrock, Richard S; Herbert, Stephen T

    2013-01-01

    Spin-based electronics or ‘spintronics’ has been a topic of interest for over two decades. Electronic devices based on the manipulation of the electron spin are believed to offer the possibility of very small, non-volatile and ultrafast devices with very low power consumption. Since the proposal of a spin-field-effect transistor (SpinFET) by Datta and Das in 1990, many attempts have been made to achieve spin injection, detection and manipulation in semiconductor materials either by incorporating ferromagnetic materials into device architectures or by using external magnetic fields. This approach has significant design complexities, partly due to the influence of stray magnetic fields on device operation. In addition, magnetic electrodes can have magneto-resistance and spurious Hall voltages that can complicate device performance. To date, there has been no successful report of a working Datta–Das SpinFET. Over the last few years we have investigated an all-electric means of manipulating spins, one that only relies on electric fields and voltages and not on ferromagnetic materials or external magnetic fields. We believe we have found a pathway toward this goal, using in-plane side-gated quantum point contacts (QPCs) that rely on lateral spin–orbit coupling to create spin polarization. In this paper we discuss several aspects of our work, beginning with our finding what we believe is nearly complete spin-polarization in InAs QPCs by purely electrical means, our theoretical work to understand the basic mechanisms leading to that situation (asymmetric lateral confinement, lateral spin–orbit coupling and a strong e–e interaction), and our recent work extending the effort to GaAs and to dual QPC systems where one QPC acts as a polarizer and the other as an analyzer. (review)

  20. Process and device for in situ replacing sealing faces in large valves

    International Nuclear Information System (INIS)

    Francois, M.; Garit, J.; Mantes, G.

    1995-01-01

    A milling machine is fitted in the interior of the valve and first machines the sealing face of the opposite seat of the seat to be replaced so that this face can act as a reference for the tool and then machines out the seat ending up by machining a new recess for the replacement seat which is then inserted in position and fixed to the body of the valve by a circular welded joint. 23 figs

  1. Candida and cardiovascular implantable electronic devices: a case of lead and native aortic valve endocarditis and literature review.

    Science.gov (United States)

    Glavis-Bloom, Justin; Vasher, Scott; Marmor, Meghan; Fine, Antonella B; Chan, Philip A; Tashima, Karen T; Lonks, John R; Kojic, Erna M

    2015-11-01

    Use of cardiovascular implantable electronic devices (CIED), including permanent pacemakers (PPM) and implantable cardioverter defibrillators (ICD), has increased dramatically over the past two decades. Most CIED infections are caused by staphylococci. Fungal causes are rare and their prognosis is poor. To our knowledge, there has not been a previously reported case of multifocal Candida endocarditis involving both a native left-sided heart valve and a CIED lead. Here, we report the case of a 70-year-old patient who presented with nausea, vomiting, and generalised fatigue, and was found to have Candida glabrata endocarditis involving both a native aortic valve and right atrial ICD lead. We review the literature and summarise four additional cases of CIED-associated Candida endocarditis published from 2009 to 2014, updating a previously published review of cases prior to 2009. We additionally review treatment guidelines and discuss management of CIED-associated Candida endocarditis. © 2015 Blackwell Verlag GmbH.

  2. Partial spin absorption induced magnetization switching and its voltage-assisted improvement in an asymmetrical all spin logic device at the mesoscopic scale

    Science.gov (United States)

    Zhang, Yue; Zhang, Zhizhong; Wang, Lezhi; Nan, Jiang; Zheng, Zhenyi; Li, Xiang; Wong, Kin; Wang, Yu; Klein, Jacques-Olivier; Khalili Amiri, Pedram; Zhang, Youguang; Wang, Kang L.; Zhao, Weisheng

    2017-07-01

    Beyond memory and storage, future logic applications put forward higher requirements for electronic devices. All spin logic devices (ASLDs) have drawn exceptional interest as they utilize pure spin current instead of charge current, which could promise ultra-low power consumption. However, relatively low efficiencies of spin injection, transport, and detection actually impede high-speed magnetization switching and challenge perspectives of ASLD. In this work, we study partial spin absorption induced magnetization switching in asymmetrical ASLD at the mesoscopic scale, in which the injector and detector have the nano-fabrication compatible device size (>100 nm) and their contact areas are different. The enlarged contact area of the detector is conducive to the spin current absorption, and the contact resistance difference between the injector and the detector can decrease the spin current backflow. Rigorous spin circuit modeling and micromagnetic simulations have been carried out to analyze the electrical and magnetic features. The results show that, at the fabrication-oriented technology scale, the ferromagnetic layer can hardly be switched by geometrically partial spin current absorption. The voltage-controlled magnetic anisotropy (VCMA) effect has been applied on the detector to accelerate the magnetization switching by modulating magnetic anisotropy of the ferromagnetic layer. With a relatively high VCMA coefficient measured experimentally, a voltage of 1.68 V can assist the whole magnetization switching within 2.8 ns. This analysis and improving approach will be of significance for future low-power, high-speed logic applications.

  3. [Coupled Analysis of Fluid-Structure Interaction of a Micro-Mechanical Valve for Glaucoma Drainage Devices].

    Science.gov (United States)

    Siewert, S; Sämann, M; Schmidt, W; Stiehm, M; Falke, K; Grabow, N; Guthoff, R; Schmitz, K-P

    2015-12-01

    Glaucoma is the leading cause of irreversible blindness worldwide. In therapeutically refractory cases, alloplastic glaucoma drainage devices (GDD) are being increasingly used to decrease intraocular pressure. Current devices are mainly limited by fibrotic encapsulation and postoperative hypotension. Preliminary studies have described the development of a glaucoma microstent to control aqueous humour drainage from the anterior chamber into the suprachoroidal space. One focus of these studies was on the design of a micro-mechanical valve placed in the anterior chamber to inhibit postoperative hypotension. The present report describes the coupled analysis of fluid-structure interaction (FSI) as basis for future improvements in the design micro-mechanical valves. FSI analysis was carried out with ANSYS 14.5 software. Solid and fluid geometry were combined in a model, and the corresponding material properties of silicone (Silastic Rx-50) and water at room temperature were assigned. The meshing of the solid and fluid domains was carried out in accordance with the results of a convergence study with tetrahedron elements. Structural and fluid mechanical boundary conditions completed the model. The FSI analysis takes into account geometric non-linearity and adaptive remeshing to consider changing geometry. A valve opening pressure of 3.26 mmHg was derived from the FSI analysis and correlates well with the results of preliminary experimental fluid mechanical studies. Flow resistance was calculated from non-linear pressure-flow characteristics as 8.5 × 10(-3) mmHg/µl  · min(-1) and 2.7 × 10(-3) mmHg/µl  · min(-1), respectively before and after valve opening pressure is exceeded. FSI analysis indicated leakage flow before valve opening, which is due to the simplified model geometry. The presented bidirectional coupled FSI analysis is a powerful tool for the development of new designs of micro-mechanical valves for GDD and may help to minimise the time and cost

  4. Significant manipulation of output performance of a bridge-structured spin valve magnetoresistance sensor via an electric field

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yue; Yan, Baiqian; Ou-Yang, Jun; Zhu, Benpeng; Chen, Shi; Yang, Xiaofei, E-mail: hust-yangxiaofei@163.com [School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074 (China); Wang, Xianghao [School of Information Engineering, Wuhan University of Technology, Wuhan 430070 (China)

    2016-01-28

    Through principles of spin-valve giant magnetoresistance (SV-GMR) effect and its application in magnetic sensors, we have investigated electric-field control of the output performance of a bridge-structured Co/Cu/NiFe/IrMn SV-GMR sensor on a PZN-PT piezoelectric substrate using the micro-magnetic simulation. We centered on the influence of the variation of uniaxial magnetic anisotropy constant (K) of Co on the output of the bridge, and K was manipulated via the stress of Co, which is generated from the strain of a piezoelectric substrate under an electric field. The results indicate that when K varies between 2 × 10{sup 4 }J/m{sup 3} and 10 × 10{sup 4 }J/m{sup 3}, the output performance can be significantly manipulated: The linear range alters from between −330 Oe and 330 Oe to between −650 Oe and 650 Oe, and the sensitivity is tuned by almost 7 times, making it possible to measure magnetic fields with very different ranges. According to the converse piezoelectric effect, we have found that this variation of K can be realized by applying an electric field with the magnitude of about 2–20 kV/cm on a PZN-PT piezoelectric substrate, which is realistic in application. This result means that electric-control of SV-GMR effect has potential application in developing SV-GMR sensors with improved performance.

  5. Significant manipulation of output performance of a bridge-structured spin valve magnetoresistance sensor via an electric field

    International Nuclear Information System (INIS)

    Zhang, Yue; Yan, Baiqian; Ou-Yang, Jun; Zhu, Benpeng; Chen, Shi; Yang, Xiaofei; Wang, Xianghao

    2016-01-01

    Through principles of spin-valve giant magnetoresistance (SV-GMR) effect and its application in magnetic sensors, we have investigated electric-field control of the output performance of a bridge-structured Co/Cu/NiFe/IrMn SV-GMR sensor on a PZN-PT piezoelectric substrate using the micro-magnetic simulation. We centered on the influence of the variation of uniaxial magnetic anisotropy constant (K) of Co on the output of the bridge, and K was manipulated via the stress of Co, which is generated from the strain of a piezoelectric substrate under an electric field. The results indicate that when K varies between 2 × 10 4  J/m 3 and 10 × 10 4  J/m 3 , the output performance can be significantly manipulated: The linear range alters from between −330 Oe and 330 Oe to between −650 Oe and 650 Oe, and the sensitivity is tuned by almost 7 times, making it possible to measure magnetic fields with very different ranges. According to the converse piezoelectric effect, we have found that this variation of K can be realized by applying an electric field with the magnitude of about 2–20 kV/cm on a PZN-PT piezoelectric substrate, which is realistic in application. This result means that electric-control of SV-GMR effect has potential application in developing SV-GMR sensors with improved performance

  6. Effects of interface electric field on the magnetoresistance in spin devices

    Energy Technology Data Exchange (ETDEWEB)

    Tanamoto, T., E-mail: tetsufumi.tanamoto@toshiba.co.jp; Ishikawa, M.; Inokuchi, T.; Sugiyama, H.; Saito, Y. [Advanced LSI Technology Laboratory Corporate Research and Development Center, Toshiba Corporation 1, Komukai Toshiba-cho, Saiwai-ku, Kawasaki 212-8582 (Japan)

    2014-04-28

    An extension of the standard spin diffusion theory is presented by using a quantum diffusion theory via a density-gradient (DG) term that is suitable for describing interface quantum tunneling phenomena. The magnetoresistance (MR) ratio is greatly modified by the DG term through an interface electric field. We have also carried out spin injection and detection measurements using four-terminal Si devices. The local measurement shows that the MR ratio changes depending on the current direction. We show that the change of the MR ratio depending on the current direction comes from the DG term regarding the asymmetry of the two interface electronic structures.

  7. Finite temperature simulation studies of spin-flop magnetic random access memory devices

    International Nuclear Information System (INIS)

    Chui, S.T.; Chang, C.-R.

    2006-01-01

    Spin-flop structures are currently being developed for magnetic random access memory devices. We report simulation studies of this system. We found the switching involves an intermediate edge-pinned domain state, similar to that observed in the single layer case. This switching scenario is quite different from that based on the coherent rotation picture. A significant temperature dependence of the switching field is observed. Our result suggests that the interplane coupling and thus the switching field has to be above a finite threshold for the spin-flop switching to be better than conventional switching methods

  8. Leading research report for fiscal 1999. Fundamental technology of spin electronic device; 1999 nendo spin toronikusu soshi kiban gijutsu kenkyu hokokusho

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2000-03-01

    The project, with attention paid to both spin and charge of electrons, aims to draw the best of the said two attributes of electrons by use of the state of the art in manufacturing technology for the creation of novel electronic devices. The nonvolatile MRAM (magnetic random access memory), which is the nearest to commercialization, is a tunnel device consisting of two sheet-shape ferromagnetic metal electrodes and an insulator film sandwiched between the said two electrodes, with the lower electrode magnetized only in one direction. The tunnel resistance changes when the magnetization direction in the upper electrode changes left and right (1, 0) according to an external writing magnetic field, and this enables nondestructive readout. The upper electrode magnetization direction remains unchanged thanks to hysteresis when the external writing magnetic field is turned off, and this allows the device to serve as a nonvolatile memory device. The device has a potential for higher speeds and enhanced integration. Much is also expected from a spin conduction functional device utilizing spin-dependent electric conduction, spin optical function device, spin quantum calculation directly utilizing quantum state, magnetic field sensor, etc. Their importance is great economically and socially, and technologies relating to magnetism and semiconductor should be merged for their further development. (NEDO)

  9. Scanning-SQUID investigation of spin-orbit torque acting on yttrium iron garnet devices

    Science.gov (United States)

    Rosenberg, Aaron J.; Jermain, Colin L.; Aradhya, Sriharsha V.; Brangham, Jack T.; Nowack, Katja C.; Kirtley, John R.; Yang, Fengyuan; Ralph, Daniel C.; Moler, Kathryn A.

    Successful manipulation of electrically insulating magnets, such as yttrium iron garnet, by by current-driven spin-orbit torques could provide a highly efficient platform for spintronic memory. Compared to devices fabricated using magnetic metals, magnetic insulators have the advantage of the ultra-low magnetic damping and the elimination of shunting currents in the magnet that reduce the torque efficiency. Here, we apply current in the spin Hall metal β-Ta to manipulate the magnetic orientation of micron-sized, electrically-insulating yttrium iron garnet devices. We do not observe spin-torque switching even for applied currents well above the critical current expected in a macrospin switching model. This suggests either inefficient transfer of spin torque at our Ta/YIG interface or a breakdown of the macrospin approximation. This work is supported by FAME, one of six centers of STARnet sponsored by MARCO and DARPA. The SQUID microscope and sensors were developed with support from the NSF-sponsored Center NSF-NSEC 0830228, and from NSF IMR-MIP 0957616.

  10. Numerical simulation of a device with two spin crossover complexes: application for temperature and pressure sensors

    Science.gov (United States)

    Linares, Jorge; Eddine Allal, Salah; Dahoo, Pierre Richard; Garcia, Yann

    2017-12-01

    The spin-crossover (SCO) phenomenon is related to the ability of a transition metal to change its spin state vs. a given perturbation. For an iron(II) SCO complexes the reversible changes involve the diamagnetic low-spin (S = 0) and the paramagnetic high-spin (HS S = 2) states [1,2,3]. In this contribution we simulate the HS Fraction (nHS) for different set values of temperature and pressure for a device using two SCO complexes with weak elastic interactions. We improve the calculation given by Linares et al. [4], taking also into account different volume (VHS, VLS) changes of the SCO. We perform all the calculation in the frame work of an Ising-like model solved in the mean-field approximation. The two SCO show in the case of “weak elastic interactions”, gradual spin transitions such that both temperature and pressure values can be obtained from the optical observation in the light of calculations discussed in this article.

  11. A device for maintenance of large diameter metal seat plug valve; Dispositivo para manutencao de valvula macho de grande diametro com sede metal-metal

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Osmar Jose Leite da [PETROBRAS, Rio de Janeiro, RJ (Brazil)

    2003-07-01

    The present work is a PETROBRAS S.A. patent request, which presents an alternative for national technology in the metal seat Plug Valve maintenance area, widely used in Petrochemical plants. Before this device, the only alternative for national companies to accomplish a reliable maintenance was to ship of the valves to their makers abroad. However, the high cost and long shipping time made this kind of maintenance unfeasible. These factors led to the beginning of the research resulting in the device described here. The device assures the valves' seat-sealing reliability. This device has been successfully used by two national Refineries : 'Presidente Bernardes' Refinery and 'Planalto Paulista' Refinery. (author)

  12. Embrella embolic deflection device for cerebral protection during transcatheter aortic valve replacement

    NARCIS (Netherlands)

    Samim, Mariam; Agostoni, Pierfrancesco; Hendrikse, Jeroen; Budde, Ricardo P J; Nijhoff, Freek; Kluin, Jolanda; Ramjankhan, Faiz; Doevendans, Pieter A.; Stella, Pieter R.

    2015-01-01

    AIMS: To compare the extent of cerebral ischemic injury after transcatheter aortic valve replacement (TAVR) with the use of an Embrella Embolic Deflector System versus unprotected TAVR. METHODS: Fifteen patients with severe symptomatic aortic stenosis underwent TAVR with use of the Embrella Embolic

  13. Embrella embolic deflection device for cerebral protection during transcatheter aortic valve replacement

    NARCIS (Netherlands)

    Samim, Mariam; Agostoni, Pierfrancesco; Hendrikse, Jeroen; Budde, Ricardo P. J.; Nijhoff, Freek; Kluin, Jolanda; Ramjankhan, Faiz; Doevendans, Pieter A.; Stella, Pieter R.

    2015-01-01

    Aims: To compare the extent of cerebral ischemic injury after transcatheter aortic valve replacement (TAVR) with the use of an Embrella Embolic Deflector System versus unprotected TAVR. Methods: Fifteen patients with severe symptomatic aortic stenosis underwent TAVR with use of the Embrella Embolic

  14. VALVE TURBO-ALTERNATOR AS ADDITIONAL HYBRID CAR DEVICE FOR THE HIGH-VOLTAGE BATTERY CHARGE

    Directory of Open Access Journals (Sweden)

    S. Kolesnikov

    2009-01-01

    Full Text Available The description of the hybrid car, its drive components and method of the solution of the problem with moving period of the car on electric pulling by means of valve turbo-alternator is given in this article.

  15. 49 CFR 179.100-13 - Venting, loading and unloading valves, measuring and sampling devices.

    Science.gov (United States)

    2010-10-01

    ... interior pipes of the loading and unloading valves shall be anchored and, except as prescribed in §§ 173... approved design. Interior pipe of the thermometer well shall be anchored in an approved manner to prevent... tank shell, the wall thickness of the pressed section must not be less than that specified for the...

  16. Back-Hopping in Spin-Transfer-Torque Devices: Possible Origin and Countermeasures

    Science.gov (United States)

    Abert, Claas; Sepehri-Amin, Hossein; Bruckner, Florian; Vogler, Christoph; Hayashi, Masamitsu; Suess, Dieter

    2018-05-01

    The effect of undesirable high-frequency free-layer switching in magnetic multilayer systems, referred to as back-hopping, is investigated by means of the spin-diffusion model. A possible origin of the back-hopping effect is found to be the destabilization of the pinned layer, which leads to the perpetual switching of both layers. While the presented mechanism is not claimed to be the only possible reason for back-hopping, we show that it is a fundamental effect that will occur in any spin-transfer-torque device when exceeding a critical current. The influence of different material parameters on the critical switching currents for the free and pinned layer is obtained by micromagnetic simulations. The spin-diffusion model enables an accurate description of the torque on both layers, depending on various material parameters. It is found that the choice of a free-layer material with low polarization β and saturation magnetization Ms and a pinned-layer material with high β and Ms leads to a low free-layer critical current and a high pinned-layer critical current and hence reduces the likelihood of back-hopping. While back-hopping has been observed in various types of devices, there are only a few experiments that exhibit this effect in perpendicularly magnetized systems. However, our simulations suggest that the described effect will also gain importance in perpendicular systems due to the loss of pinned-layer anisotropy for decreasing device sizes.

  17. Spin-Polarized Tunneling through Chemical Vapor Deposited Multilayer Molybdenum Disulfide.

    Science.gov (United States)

    Dankert, André; Pashaei, Parham; Kamalakar, M Venkata; Gaur, Anand P S; Sahoo, Satyaprakash; Rungger, Ivan; Narayan, Awadhesh; Dolui, Kapildeb; Hoque, Md Anamul; Patel, Ram Shanker; de Jong, Michel P; Katiyar, Ram S; Sanvito, Stefano; Dash, Saroj P

    2017-06-27

    The two-dimensional (2D) semiconductor molybdenum disulfide (MoS 2 ) has attracted widespread attention for its extraordinary electrical-, optical-, spin-, and valley-related properties. Here, we report on spin-polarized tunneling through chemical vapor deposited multilayer MoS 2 (∼7 nm) at room temperature in a vertically fabricated spin-valve device. A tunnel magnetoresistance (TMR) of 0.5-2% has been observed, corresponding to spin polarization of 5-10% in the measured temperature range of 300-75 K. First-principles calculations for ideal junctions result in a TMR up to 8% and a spin polarization of 26%. The detailed measurements at different temperature, bias voltages, and density functional theory calculations provide information about spin transport mechanisms in vertical multilayer MoS 2 spin-valve devices. These findings form a platform for exploring spin functionalities in 2D semiconductors and understanding the basic phenomena that control their performance.

  18. Novel spintronics devices for memory and logic: prospects and challenges for room temperature all spin computing

    Science.gov (United States)

    Wang, Jian-Ping

    An energy efficient memory and logic device for the post-CMOS era has been the goal of a variety of research fields. The limits of scaling, which we expect to reach by the year 2025, demand that future advances in computational power will not be realized from ever-shrinking device sizes, but rather by innovative designs and new materials and physics. Magnetoresistive based devices have been a promising candidate for future integrated magnetic computation because of its unique non-volatility and functionalities. The application of perpendicular magnetic anisotropy for potential STT-RAM application was demonstrated and later has been intensively investigated by both academia and industry groups, but there is no clear path way how scaling will eventually work for both memory and logic applications. One of main reasons is that there is no demonstrated material stack candidate that could lead to a scaling scheme down to sub 10 nm. Another challenge for the usage of magnetoresistive based devices for logic application is its available switching speed and writing energy. Although a good progress has been made to demonstrate the fast switching of a thermally stable magnetic tunnel junction (MTJ) down to 165 ps, it is still several times slower than its CMOS counterpart. In this talk, I will review the recent progress by my research group and my C-SPIN colleagues, then discuss the opportunities, challenges and some potential path ways for magnetoresitive based devices for memory and logic applications and their integration for room temperature all spin computing system.

  19. Catheter Ablation of Atrial Fibrillation in Patients with Hardware in the Heart - Septal Closure Devices, Mechanical Valves and More.

    Science.gov (United States)

    Bartoletti, Stefano; Santangeli, Pasquale; DI Biase, Luigi; Natale, Andrea

    2013-01-01

    Patients with mechanical "hardware" in the heart, such as those with mechanical cardiac valves or atrial septal closure devices, represent a population at high risk of developing AF. Catheter ablation of AF in these subjects might represent a challenge, due to the perceived higher risk of complications associated with the presence of intracardiac mechanical devices. Accordingly, such patients were excluded or poorly represented in major trials proving the benefit of catheter ablation for the rhythm-control of AF. However, recent evidence supports the concept that catheter ablation procedures might be equally effective in these patients, without a significant increase in the risk of procedural complications. This review will summarize the current state-of-the-art on catheter ablation of AF in patients with mechanical "hardware" in the heart.

  20. Wound dehiscence and device migration after subconjunctival bevacizumab injection with Ahmed glaucoma valve implantation

    OpenAIRE

    Arezoo Miraftabi; Naveed Nilforushan

    2016-01-01

    Purpose: To report a complication pertaining to subconjunctival bevacizumab injection as an adjunct to Ahmed Glaucoma Valve (AGV) implantation. Case Report: A 54-year-old woman with history of complicated cataract surgery was referred for advanced intractable glaucoma. AGV implantation with adjunctive subconjunctival bevacizumab (1.25 mg) was performed with satisfactory results during the first postoperative week. However, 10 days after surgery, she developed wound dehiscence and tube exposur...

  1. The iValve Hands-Free Speech Valve for Laryngectomized Patients. In Vitro Test of a Novel Device of Revolutionary Design

    NARCIS (Netherlands)

    van der Houwen, E. B.; van Kalkeren, T. A.; Burgerhof, J. G. M.; van der Laan, B. F. A. M.; Verkerke, G. J.; Jobbagy, A

    2012-01-01

    Background. Speech valves help restore speech after surgical removal of the larynx (laryngectomy). Laryngectomized Patients breathe through an artificial opening (tracheostoma) in the neck. A shunt valve is routinely inserted between oesophagus and trachea to restore speech. At closure of the stoma

  2. Effects of non-latching blast valves on the source term and consequences of the design-basis accidents in the Device Assembly Facility (DAF)

    International Nuclear Information System (INIS)

    Nguyen, D.H.

    1993-08-01

    The analysis of the Design-Basis Accidents (DBA) involving high explosives (HE) and Plutonium (Pu) in the assembly cell of the Device Assembly Facility (DAF), which was completed earlier, assumed latching blast valves in the ventilation system of the assembly cell. Latching valves effectively sealed a release path through the ventilation duct system. However, the blast valves in the assembly cell, as constructed are actually non-latching valves, and would reopen when the gas pressure drops to 0.5 psi above one atmosphere. Because the reopening of the blast valves provides an additional release path to the environment, and affects the material transport from the assembly cell to other DAF buildings, the DOE/NV DAF management has decided to support an additional analysis of the DAF's DBA to account for the effects of non-latching valves. Three cases were considered in the DAF's DBA, depending on the amount of HE and Pu involved, as follows: Case 1 -- 423 number-sign HE, 16 kg Pu; Case 2 -- 150 number-sign HE 10 kg Pu; Case 3 -- 55 number-sign HE 5 kg Pu. The results of the analysis with non-latching valves are summarized

  3. Sub-10 nm colloidal lithography for circuit-integrated spin-photo-electronic devices

    Directory of Open Access Journals (Sweden)

    Adrian Iovan

    2012-12-01

    Full Text Available Patterning of materials at sub-10 nm dimensions is at the forefront of nanotechnology and employs techniques of various complexity, efficiency, areal scale, and cost. Colloid-based patterning is known to be capable of producing individual sub-10 nm objects. However, ordered, large-area nano-arrays, fully integrated into photonic or electronic devices have remained a challenging task. In this work, we extend the practice of colloidal lithography to producing large-area sub-10 nm point-contact arrays and demonstrate their circuit integration into spin-photo-electronic devices. The reported nanofabrication method should have broad application areas in nanotechnology as it allows ballistic-injection devices, even for metallic materials with relatively short characteristic relaxation lengths.

  4. Valve monitoring ITI-MOVATS

    International Nuclear Information System (INIS)

    Moureau, S.

    1993-01-01

    ITI-MOVATS provides a wide range of test devices to monitor the performance of valves: motor operated gate or globe valve, butterfly valve, air operated valve, and check valve. The ITI-MOVATS testing equipment is used in the following three areas: actuator setup/baseline testing, periodic/post-maintenance testing, and differential pressure testing. The parameters typically measured with the MOVATS diagnostic system as well as the devices used to measure them are described. (Z.S.)

  5. High and tunable spin current induced by magnetic-electric fields in a single-mode spintronic device

    International Nuclear Information System (INIS)

    Bala Kumar, S; Jalil, M B A; Tan, S G; Liang, G-C

    2009-01-01

    We proposed that a viable form of spin current transistor is one to be made from a single-mode device which passes electrons through a series of magnetic-electric barriers built into the device. The barriers assume a wavy spatial profile across the conduction path due to the inevitable broadening of the magnetic fields. Field broadening results in a linearly increasing vector potential across the conduction channel, which increases spin polarization. We have identified that the important factors for generating high spin polarization and conductance modulation are the low source-drain bias, the broadened magnetic fields, and the high number of FM gates within a fixed channel length.

  6. Pacemaker implantation rate after transcatheter aortic valve implantation with early and new-generation devices: a systematic review.

    Science.gov (United States)

    van Rosendael, Philippe J; Delgado, Victoria; Bax, Jeroen J

    2018-02-06

    The incidence of new-onset conduction abnormalities requiring permanent pacemaker implantation (PPI) after transcatheter aortic valve implantation (TAVI) with new-generation prostheses remains debated. This systematic review analyses the incidence of PPI after TAVI with new-generation devices and evaluates the electrical, anatomical, and procedural factors associated with PPI. In addition, the incidence of PPI after TAVI with early generation prostheses was reviewed for comparison. According to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses checklist, this systematic review screened original articles published between October 2010 and October 2017, reporting on the incidence of PPI after implantation of early and new-generation TAVI prostheses. Of the 1406 original articles identified in the first search for new-generation TAVI devices, 348 articles were examined for full text, and finally, 40 studies (n = 17 139) were included. The incidence of a PPI after the use of a new-generation TAVI prosthesis ranged between 2.3% and 36.1%. For balloon-expandable prostheses, the PPI rate remained low when using an early generation SAPIEN device (ranging between 2.3% and 28.2%), and with the new-generation SAPIEN 3 device, the PPI rate was between 4.0% and 24.0%. For self-expandable prostheses, the PPI rates were higher with the early generation CoreValve device (16.3-37.7%), and despite a reduction in PPI rates with the new Evolut R, the rates remained relatively higher (14.7-26.7%). When dividing the studies according to the highest (>26.0%) and the lowest (left ventricular outflow tract (anatomical factor), and balloon valvuloplasty and depth of implantation (procedural factors) were associated with increased risk of PPI. The rate of PPI after TAVI with new-generation devices is highly variable. Specific recommendations for implantation of each prosthesis, taking into consideration the presence of pre-existent conduction abnormalities and

  7. Spin coated graphene films as the transparent electrode in organic photovoltaic devices

    International Nuclear Information System (INIS)

    Kymakis, E.; Stratakis, E.; Stylianakis, M.M.; Koudoumas, E.; Fotakis, C.

    2011-01-01

    Many research efforts have been devoted to the replacement of the traditional indium–tin-oxide (ITO) electrode in organic photovoltaics. Solution-based graphene has been identified as a potential replacement, since it has less than two percent absorption per layer, relative high carrier mobility, and it offers the possibility of deposition on large area and flexible substrates, compatible with roll to roll manufacturing methods. In this work, soluble reduced graphene films with high electrical conductivity and transparency were fabricated and incorporated in poly(3-hexylthiophene) [6,6]-phenyl-C 61 -butyric acid methyl ester photovoltaic devices, as the transparent electrode. The graphene films were spin coated on glass from an aqueous dispersion of functionalized graphene, followed by a reduction process combining hydrazine vapor and annealing under argon, in order to reduce the sheet resistance. The photovoltaic devices obtained from the graphene films showed lower performance than the reference devices with ITO, due to the higher sheet resistance (2 kΩ/sq) and the poor hydrophilicity of the spin coated graphene films.

  8. Voltage-Controlled Reconfigurable Spin-Wave Nanochannels and Logic Devices

    Science.gov (United States)

    Rana, Bivas; Otani, YoshiChika

    2018-01-01

    Propagating spin waves (SWs) promise to be a potential information carrier in future spintronics devices with lower power consumption. Here, we propose reconfigurable nanochannels (NCs) generated by voltage-controlled magnetic anisotropy (VCMA) in an ultrathin ferromagnetic waveguide for SW propagation. Numerical micromagnetic simulations are performed to demonstrate the confinement of magnetostatic forward volumelike spin waves in NCs by VCMA. We demonstrate that the NCs, with a width down to a few tens of a nanometer, can be configured either into a straight or curved structure on an extended SW waveguide. The key advantage is that either a single NC or any combination of a number of NCs can be easily configured by VCMA for simultaneous propagation of SWs either with the same or different wave vectors according to our needs. Furthermore, we demonstrate the logic operation of a voltage-controlled magnonic xnor and universal nand gate and propose a voltage-controlled reconfigurable SW switch for the development of a multiplexer and demultiplexer. We find that the NCs and logic devices can even be functioning in the absence of the external-bias magnetic field. These results are a step towards the development of all-voltage-controlled magnonic devices with an ultralow power consumption.

  9. Observation of spin-polarized electron transport in Alq3 by using a low work function metal

    Science.gov (United States)

    Jang, Hyuk-Jae; Pernstich, Kurt P.; Gundlach, David J.; Jurchescu, Oana D.; Richter, Curt. A.

    2012-09-01

    We present the observation of magnetoresistance in Co/Ca/Alq3/Ca/NiFe spin-valve devices. Thin Ca layers contacting 150 nm thick Alq3 enable the injection of spin-polarized electrons into Alq3 due to the engineering of the band alignment. The devices exhibit symmetric current-voltage (I-V) characteristics indicating identical metal contacts on Alq3, and up to 4% of positive magnetoresistance was observed at 4.5 K. In contrast, simultaneously fabricated Co/Alq3/NiFe devices displayed asymmetric I-V curves due to the different metal electrodes, and spin-valve effects were not observed.

  10. First-in-man use of a novel embolic protection device for patients undergoing transcatheter aortic valve implantation.

    Science.gov (United States)

    Naber, Christoph K; Ghanem, Alexander; Abizaid, Alexander A; Wolf, Alexander; Sinning, Jan-Malte; Werner, Nikos; Nickenig, Georg; Schmitz, Thomas; Grube, Eberhard

    2012-05-15

    We describe the first-in-human experience with a novel cerebral embolic protection device used during transcatheter aortic valve implantation (TAVI). One current challenge of TAVI is the reduction of procedural stroke. Procedural mobilisation of debris is a known source of cerebral embolisation. Mechanical protection by transient filtration of cerebral blood flow might reduce the embolic burden during TAVI. We aimed to evaluate the feasibility and safety of the Claret CE Pro™ cerebral protection device in patients undergoing TAVI. Patients scheduled for TAVI were prospectively enrolled at three centres. The Claret CE Pro™ (Claret Medical, Inc. Santa Rosa, CA, USA) cerebral protection device was placed via the right radial/brachial artery prior to TAVI and was removed after the procedure. The primary endpoint was technical success rate. Secondary endpoints encompassed procedural and 30-day stroke rates, as well as device-related complications. Deployment of the Claret CE Pro™ cerebral protection device was intended for use in 40 patients, 35 devices were implanted into the aortic arch. Technical success rate with delivery of the proximal and distal filter was 60% for the first generation device and 87% for the second-generation device. Delivery times for the first-generation device were 12.4±12.1 minutes and 4.4 ± 2.5 minutes for the second-generation device (pto the Claret CE Pro System was 19.6 ± 3.8 ml. Captured debris was documented in at least 19 of 35 implanted devices (54.3%). No procedural transient ischaemic attacks, minor strokes or major strokes occurred. Thirty-day follow-up showed one minor stroke occurring 30 days after the procedure, and two major strokes both occurring well after the patient had completed TAVI. The use of the Claret CE Pro™ system is feasible and safe. Capture of debris in more than half of the patients provides evidence for the potential to reduce the procedural cerebral embolic burden utilising this dedicated filter

  11. Spin-polarized transport properties of a pyridinium-based molecular spintronics device

    Science.gov (United States)

    Zhang, J.; Xu, B.; Qin, Z.

    2018-05-01

    By applying a first-principles approach based on non-equilibrium Green's functions combined with density functional theory, the transport properties of a pyridinium-based "radical-π-radical" molecular spintronics device are investigated. The obvious negative differential resistance (NDR) and spin current polarization (SCP) effect, and abnormal magnetoresistance (MR) are obtained. Orbital reconstruction is responsible for novel transport properties such as that the MR increases with bias and then decreases and that the NDR being present for both parallel and antiparallel magnetization configurations, which may have future applications in the field of molecular spintronics.

  12. Wound Dehiscence and Device Migration after Subconjunctival Bevacizumab Injection with Ahmed Glaucoma Valve Implantation.

    Science.gov (United States)

    Miraftabi, Arezoo; Nilforushan, Naveed

    2016-01-01

    To report a complication pertaining to subconjunctival bevacizumab injection as an adjunct to Ahmed Glaucoma Valve (AGV) implantation. A 54-year-old woman with history of complicated cataract surgery was referred for advanced intractable glaucoma. AGV implantation with adjunctive subconjunctival bevacizumab (1.25 mg) was performed with satisfactory results during the first postoperative week. However, 10 days after surgery, she developed wound dehiscence and tube exposure. The second case was a 33-year-old man with history of congenital glaucoma and uncontrolled IOP who developed AGV exposure and wound dehiscence after surgery. In both cases, for prevention of endophthalmitis and corneal damage by the unstable tube, the shunt was removed and the conjunctiva was re-sutured. The potential adverse effect of subconjunctival bevacizumab injection on wound healing should be considered in AGV surgery.

  13. Novel room-temperature spin-valve-like magnetoresistance in magnetically coupled nano-column Fe3O4/Ni heterostructure.

    Science.gov (United States)

    Xiao, Wen; Song, Wendong; Herng, Tun Seng; Qin, Qing; Yang, Yong; Zheng, Ming; Hong, Xiaoliang; Feng, Yuan Ping; Ding, Jun

    2016-08-25

    Herein, we design a room-temperature spin-valve-like magnetoresistance in a nano-column Fe3O4/Ni heterostructure without using a non-magnetic spacer or pinning layer. An Fe3O4 nano-column film is self-assembled on a Ni underlayer by the thermal decomposition method. The wet-chemical self-assembly is facile, economical and scalable. The magnetoresistance (MR) response of the Ni underlayer in the heterostructure under positive and negative out-of-plane magnetic fields differ by ∼0.25 at room temperature and ∼0.43 at 100 K. We attribute the spin-valve-like magnetoresistance to the unidirectional magnetic anisotropy of the Ni underlayer when being magnetically coupled by the Fe3O4 nano-column film. The out-of-plane negative-field magnetization is higher than the positive-field magnetization, affirming the unidirectional magnetic anisotropy of the Fe3O4/Ni heterostructure. Temperature-dependent magnetic and resistivity studies illustrate a close correlation between the magnetization transition of Fe3O4 and resistivity transition of Ni and prove a magnetic coupling between the Fe3O4 and Ni. First-principles calculations reveal that the Fe3O4/Ni model under a negative magnetic field is energetically more stable than that under a positive magnetic field. Furthermore, partial density of states (PDOS) analysis demonstrates the unidirectional magnetic anisotropy of the Ni 3d orbital. This is induced by the strong ferromagnetic coupling between Fe3O4 and Ni via oxygen-mediated Fe 3d-O 2p-Ni 3d hybridizations.

  14. Injection of Spin-Polarized Electrons into a AlGaN/GaN Device from an Electrochemical Cell: Evidence for an Extremely Long Spin Lifetime.

    Science.gov (United States)

    Kumar, Anup; Capua, Eyal; Fontanesi, Claudio; Carmieli, Raanan; Naaman, Ron

    2018-04-24

    Spin-polarized electrons are injected from an electrochemical cell through a chiral self-assembled organic monolayer into a AlGaN/GaN device in which a shallow two-dimensional electron gas (2DEG) layer is formed. The injection is monitored by a microwave signal that indicates a coherent spin lifetime that exceeds 10 ms at room temperature. The signal was found to be magnetic field independent; however, it depends on the current of the injected electrons, on the length of the chiral molecules, and on the existence of 2DEG.

  15. Modeling the collective excitations in a full Heusler Co2 FeAl0.5 Si0.5 (CFAS) spin valve magnetic nanopillar in the electromagnetic field

    International Nuclear Information System (INIS)

    David, Cherine; Arumugam, Brinda; Rajamani, Amuda; Natarajan, Kanimozhi

    2014-01-01

    This paper describes the physics of collective excitations that are caused by spin-transfer torques in CFAS magnetic multilayer. When the magnetizations of the pinned and free layers are not collinear with each other, the spin-polarized currents transfer angular momentum to the magnetizations near the interfaces, giving rise to spin-transfer torques. The currents in magnetic multilayer are spin polarised and can carry enough angular momentum. When an electron spin carried by the current interacts with a magnetic layer, the exchange interaction leads to torque between the spin and the magnetization vector of the free layer. This is Spin Transfer Torque (STT) and it excites the magnetization when it is large enough. The Spin Transfer Torque induced collective excitations for the CFAS spin valve pillar have been extensively studied in this paper. - Highlights: • We have modeled LLGS equation for CFAS multilayer array. • The dynamics of collective excitation induced by STT is investigated. • The interactions exhibit solitonic behaviour at both limiting modes of polarization. • The spin components of the solitons are graphically represented

  16. Spin relaxation through lateral spin transport in heavily doped n -type silicon

    Science.gov (United States)

    Ishikawa, M.; Oka, T.; Fujita, Y.; Sugiyama, H.; Saito, Y.; Hamaya, K.

    2017-03-01

    We experimentally study temperature-dependent spin relaxation including lateral spin diffusion in heavily doped n -type silicon (n+-Si ) layers by measuring nonlocal magnetoresistance in small-sized CoFe/MgO/Si lateral spin-valve (LSV) devices. Even at room temperature, we observe large spin signals, 50-fold the magnitude of those in previous works on n+-Si . By measuring spin signals in LSVs with various center-to-center distances between contacts, we reliably evaluate the temperature-dependent spin diffusion length (λSi) and spin lifetime (τSi). We find that the temperature dependence of τSi is affected by that of the diffusion constant in the n+-Si layers, meaning that it is important to understand the temperature dependence of the channel mobility. A possible origin of the temperature dependence of τSi is discussed in terms of the recent theories by Dery and co-workers.

  17. Impact of tricuspid valve surgery at the time of left ventricular assist device insertion on postoperative outcomes.

    Science.gov (United States)

    Dunlay, Shannon M; Deo, Salil V; Park, Soon J

    2015-01-01

    Tricuspid regurgitation (TR) is common in patients with heart failure undergoing left ventricular assist device (LVAD) implantation. Whether the TR should be surgically managed at the time of LVAD surgery is controversial. We searched SCOPUS, Web of Science, Ovid EMBASE, and Ovid MEDLINE (through May 10, 2014) for randomized controlled trials and observational studies comparing postoperative outcomes in patients treated with LVAD with concomitant tricuspid valve surgery (TVS) compared with LVAD alone. Six observational studies including 3,249 patients compared outcomes following LVAD + TVS versus LVAD. Four studies were single-center and most did not adjust for potential confounders. Addition of TVS prolonged cardiopulmonary bypass times by an average of 31 minutes (three studies, 95% CI 20-42). There was no difference in need for right ventricular assist device (six studies, HR 1.42, 95% CI 0.54-3.76), acute renal failure (four studies, HR 1.07, 95% CI 0.55-2.10), or early mortality (six studies, HR 1.28, 95% CI 0.78-2.08) in patients treated with LVAD + TVS versus LVAD alone. TVS prolongs cardiopulmonary bypass times, but available data demonstrate no significant association with early postoperative outcomes. However, differences in baseline risk of patients treated with TVS versus not limit our ability to draw conclusions.

  18. Role of radionuclide imaging for diagnosis of device and prosthetic valve infections

    Institute of Scientific and Technical Information of China (English)

    Jean-Fran?ois Sarrazin; Fran?ois Philippon; Mika?l Trottier; Michel Tessier

    2016-01-01

    Cardiovascular implantable electronic device(CIED) infection and prosthetic valve endocarditis(PVE) remain a diagnostic challenge.Cardiac imaging plays an important role in the diagnosis and management of patients with CIED infection or PVE.Over the past few years,cardiac radionuclide imaging has gained a key role in the diagnosis of these patients,and in assessing the need for surgery,mainly in the most difficult cases.Both 18F-fluorodeoxyglucose positron emission tomography/computed tomography(18F-FDG PET/CT) and radiolabelled white blood cell single-photon emission computed tomography/computed tomography(WBC SPECT/CT) have been studied in these situations.In their 2015 guidelines for the management of infective endocarditis,the European Society of Cardiology incorporated cardiac nuclear imaging as part of their diagnostic algorithm for PVE,but not CIED infection since the data were judged insufficient at the moment.This article reviews the actual knowledge and recent studies on the use of 18F-FDG PET/CT and WBC SPECT/CT in the context of CIED infection and PVE,and describes the technical aspects of cardiac radionuclide imaging.It also discusses their accepted and potential indications for the diagnosis and management of CIED infection and PVE,the limitations of these tests,and potential areas of future research.

  19. Post-operative ventricular flow dynamics following atrioventricular valve surgical and device therapies: A review.

    Science.gov (United States)

    Nguyen, Yen Ngoc; Ismail, Munirah; Kabinejadian, Foad; Tay, Edgar Lik Wui; Leo, Hwa Liang

    2018-04-01

    Intra-ventricular flow dynamics has recently emerged as an important evaluation and diagnosis tool in different cardiovascular conditions. The formation of vortex pattern during the cardiac cycle has been suggested to play important epigenetic and energy-modulation roles in cardiac remodelling, adaptations and mal-adaptations. In this new perspective, flow alterations due to different cardiovascular procedures can affect the long-term outcome of those procedures. Especially, repairs and replacements performed on atrioventricular valves are likely to exert direct impact on intra-ventricular flow pattern. In this review, current consensus around the roles of vortex dynamics in cardiac function is discussed. An overview of physiological vortex patterns found in healthy left and right ventricles as well as post-operative ventricular flow phenomenon owing to different atrioventricular valvular procedures are reviewed, followed by the summary of different vortex identification schemes used to characterise intraventricular flow. This paper also emphasises on future research directions towards a comprehensive understanding of intra-cardiac flow and its clinical relevance. The knowledge could encourage more effective pre-operative planning and better outcomes for current clinical practices. Copyright © 2018. Published by Elsevier Ltd.

  20. Effect of resistance feedback on spin torque-induced switching of nanomagnets

    International Nuclear Information System (INIS)

    Garzon, Samir; Webb, Richard A.; Covington, Mark; Kaka, Shehzaad; Crawford, Thomas M.

    2009-01-01

    In large magnetoresistance devices spin torque-induced changes in resistance can produce GHz current and voltage oscillations which can affect magnetization reversal. In addition, capacitive shunting in large resistance devices can further reduce the current, adversely affecting spin torque switching. Here, we simultaneously solve the Landau-Lifshitz-Gilbert equation with spin torque and the transmission line telegrapher's equations to study the effects of resistance feedback and capacitance on magnetization reversal of both spin valves and magnetic tunnel junctions. While for spin valves parallel (P) to anti-parallel (AP) switching is adversely affected by the resistance feedback due to saturation of the spin torque, in low resistance magnetic tunnel junctions P-AP switching is enhanced. We study the effect of resistance feedback on the switching time of magnetic tunnel junctions, and show that magnetization switching is only affected by capacitive shunting in the pF range.

  1. Half-metallic superconducting triplet spin multivalves

    Science.gov (United States)

    Alidoust, Mohammad; Halterman, Klaus

    2018-02-01

    We study spin switching effects in finite-size superconducting multivalve structures. We examine F1F2SF3 and F1F2SF3F4 hybrids where a singlet superconductor (S) layer is sandwiched among ferromagnet (F) layers with differing thicknesses and magnetization orientations. Our results reveal a considerable number of experimentally viable spin-valve configurations that lead to on-off switching of the superconducting state. For S widths on the order of the superconducting coherence length ξ0, noncollinear magnetization orientations in adjacent F layers with multiple spin axes leads to a rich variety of triplet spin-valve effects. Motivated by recent experiments, we focus on samples where the magnetizations in the F1 and F4 layers exist in a fully spin-polarized half-metallic phase, and calculate the superconducting transition temperature, spatially and energy resolved density of states, and the spin-singlet and spin-triplet superconducting correlations. Our findings demonstrate that superconductivity in these devices can be completely switched on or off over a wide range of magnetization misalignment angles due to the generation of equal-spin and opposite-spin triplet pairings.

  2. Thermal Blood Clot Formation and use in Microfluidic Device Valving Applications

    Science.gov (United States)

    Tai, Yu-Chong (Inventor); Shi, Wendian (Inventor); Guo, Luke (Inventor)

    2014-01-01

    The present invention provides a method of forming a blood-clot microvalve by heating blood in a capillary tube of a microfluidic device. Also described are methods of modulating liquid flow in a capillary tube by forming and removing a blood-clot microvalve.

  3. 49 CFR 178.337-9 - Pressure relief devices, piping, valves, hoses, and fittings.

    Science.gov (United States)

    2010-10-01

    ... heavier, except for sacrificial devices. Malleable metal, stainless steel, or ductile iron must be used in.... Stainless steel may be used for internal components such as shutoff discs and springs except where... inspections in § 180.416(f) of this subchapter. (iii) Mark each hose assembly with the month and year of its...

  4. Achieving perpendicular anisotropy in half-metallic Heusler alloys for spin device applications

    Science.gov (United States)

    Munira, Kamaram; Romero, Jonathon; Butler, William H.

    2014-05-01

    Various full Heusler alloys are interfaced with MgO and the magnetic properties of the Heusler-MgO junctions are studied. Next to MgO, the cubic Heusler system distorts to a tetragonal one, thereby inducing an anisotropy. The half-metallicity and nature of anisotropy (in-plane or perpendicular) in the Heusler-MgO system is governed mostly by the interface Heusler layers. There is a trend that Mn-O bonding near the MgO-Heusler junction results in perpendicular anisotropy. The ability to remain half-metallic and have perpendicular anisotropy makes some of these alloys potential candidates as free-layers in Spin Transfer Torque Random Access Memory (STT-RAM) devices, particularly, Cr2MnAs-MgO system with MnAs interface layers and Co2MnSi-MgO system with Mn2 interface layers.

  5. PREFACE: Spin Electronics

    Science.gov (United States)

    Dieny, B.; Sousa, R.; Prejbeanu, L.

    2007-04-01

    Conventional electronics has in the past ignored the spin on the electron, however things began to change in 1988 with the discovery of giant magnetoresistance in metallic thin film stacks which led to the development of a new research area, so called spin-electronics. In the last 10 years, spin-electronics has achieved a number of breakthroughs from the point of view of both basic science and application. Materials research has led to several major discoveries: very large tunnel magnetoresistance effects in tunnel junctions with crystalline barriers due to a new spin-filtering mechanism associated with the spin-dependent symmetry of the electron wave functions new magnetic tunnelling barriers leading to spin-dependent tunnelling barrier heights and acting as spin-filters magnetic semiconductors with increasingly high ordering temperature. New phenomena have been predicted and observed: the possibility of acting on the magnetization of a magnetic nanostructure with a spin-polarized current. This effect, due to a transfer of angular momentum between the spin polarized conduction electrons and the local magnetization, can be viewed as the reciprocal of giant or tunnel magnetoresistance. It can be used to switch the magnetization of a magnetic nanostructure or to generate steady magnetic excitations in the system. the possibility of generating and manipulating spin current without charge current by creating non-equilibrium local accumulation of spin up or spin down electrons. The range of applications of spin electronics materials and phenomena is expanding: the first devices based on giant magnetoresistance were the magnetoresistive read-heads for computer disk drives. These heads, introduced in 1998 with current-in plane spin-valves, have evolved towards low resistance tunnel magnetoresistice heads in 2005. Besides magnetic recording technology, these very sensitive magnetoresistive sensors are finding applications in other areas, in particular in biology. magnetic

  6. A perfect spin filtering device through Mach-Zehnder interferometry in a GaAs/AlGaAs electron gas

    Energy Technology Data Exchange (ETDEWEB)

    Lopez, Alexander; Medina, Ernesto [Centro de Fisica, Instituto Venezolano de Investigaciones CientIficas, Apartado 21874, Caracas 1020-A (Venezuela, Bolivarian Republic of); BolIvar, Nelson [Departamento de Fisica, Universidad Central de Venezuela, Caracas (Venezuela, Bolivarian Republic of); Berche, Bertrand [Statistical Physics Group, P2M, Institut Jean Lamour, Nancy Universite, BP70239, F-54506 Vandoeuvre les Nancy (France)

    2010-03-24

    A spin filtering device based on quantum spin interference is addressed, for use with a two-dimensional GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus spin-orbit (SO) couplings and an applied external magnetic field. We propose an experimentally feasible electronic Mach-Zehnder interferometer and derive a map, in parameter space, that determines perfect spin filtering conditions. We find two broad spin filtering regimes: one where filtering is achieved in the original incoming quantization basis, that takes advantage of the purely non-Abelian nature of the spin rotations; and another where one needs a tilted preferential axis in order to observe the polarized output spinor. Both solutions apply for arbitrary incoming electron polarization and energy, and are only limited in output amplitude by the randomness of the incoming spinor state. Including a full account of the beam splitter and mirror effects on spin yields solutions only for the tilted basis, but encompasses a broad range of filtering conditions.

  7. A perfect spin filtering device through Mach-Zehnder interferometry in a GaAs/AlGaAs electron gas

    International Nuclear Information System (INIS)

    Lopez, Alexander; Medina, Ernesto; BolIvar, Nelson; Berche, Bertrand

    2010-01-01

    A spin filtering device based on quantum spin interference is addressed, for use with a two-dimensional GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus spin-orbit (SO) couplings and an applied external magnetic field. We propose an experimentally feasible electronic Mach-Zehnder interferometer and derive a map, in parameter space, that determines perfect spin filtering conditions. We find two broad spin filtering regimes: one where filtering is achieved in the original incoming quantization basis, that takes advantage of the purely non-Abelian nature of the spin rotations; and another where one needs a tilted preferential axis in order to observe the polarized output spinor. Both solutions apply for arbitrary incoming electron polarization and energy, and are only limited in output amplitude by the randomness of the incoming spinor state. Including a full account of the beam splitter and mirror effects on spin yields solutions only for the tilted basis, but encompasses a broad range of filtering conditions.

  8. A perfect spin filtering device through Mach-Zehnder interferometry in a GaAs/AlGaAs electron gas

    Science.gov (United States)

    López, Alexander; Medina, Ernesto; Bolívar, Nelson; Berche, Bertrand

    2010-03-01

    A spin filtering device based on quantum spin interference is addressed, for use with a two-dimensional GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus spin-orbit (SO) couplings and an applied external magnetic field. We propose an experimentally feasible electronic Mach-Zehnder interferometer and derive a map, in parameter space, that determines perfect spin filtering conditions. We find two broad spin filtering regimes: one where filtering is achieved in the original incoming quantization basis, that takes advantage of the purely non-Abelian nature of the spin rotations; and another where one needs a tilted preferential axis in order to observe the polarized output spinor. Both solutions apply for arbitrary incoming electron polarization and energy, and are only limited in output amplitude by the randomness of the incoming spinor state. Including a full account of the beam splitter and mirror effects on spin yields solutions only for the tilted basis, but encompasses a broad range of filtering conditions.

  9. Spin injection into Pt-polymers with large spin-orbit coupling

    Science.gov (United States)

    Sun, Dali; McLaughlin, Ryan; Siegel, Gene; Tiwari, Ashutosh; Vardeny, Z. Valy

    2014-03-01

    Organic spintronics has entered a new era of devices that integrate organic light-emitting diodes (OLED) in organic spin valve (OSV) geometry (dubbed bipolar organic spin valve, or spin-OLED), for actively manipulating the device electroluminescence via the spin alignment of two ferromagnetic electrodes (Science 337, 204-209, 2012; Appl. Phys. Lett. 103, 042411, 2013). Organic semiconductors that contain heavy metal elements have been widely used as phosphorescent dopants in white-OLEDs. However such active materials are detrimental for OSV operation due to their large spin-orbit coupling (SOC) that may limit the spin diffusion length and thus spin-OLED based on organics with large SOC is a challenge. We report the successful fabrication of OSVs based on pi-conjugated polymers which contain intrachain Platinum atoms (dubbed Pt-polymers). Spin injection into the Pt-polymers is investigated by the giant magnetoresistance (GMR) effect as a function of bias voltage, temperature and polymer layer thickness. From the GMR bias voltage dependence we infer that the ``impendence mismatch'' between ferromagnetic electrodes and Pt-polymer may be suppressed due to the large SOC. Research sponsored by the NSF (Grant No. DMR-1104495) and NSF-MRSEC (DMR 1121252) at the University of Utah.

  10. Simulation study of ballistic spin-MOSFET devices with ferromagnetic channels based on some Heusler and oxide compounds

    Science.gov (United States)

    Graziosi, Patrizio; Neophytou, Neophytos

    2018-02-01

    Newly emerged materials from the family of Heuslers and complex oxides exhibit finite bandgaps and ferromagnetic behavior with Curie temperatures much higher than even room temperature. In this work, using the semiclassical top-of-the-barrier FET model, we explore the operation of a spin-MOSFET that utilizes such ferromagnetic semiconductors as channel materials, in addition to ferromagnetic source/drain contacts. Such a device could retain the spin polarization of injected electrons in the channel, the loss of which limits the operation of traditional spin transistors with non-ferromagnetic channels. We examine the operation of four material systems that are currently considered some of the most prominent known ferromagnetic semiconductors: three Heusler-type alloys (Mn2CoAl, CrVZrAl, and CoVZrAl) and one from the oxide family (NiFe2O4). We describe their band structures by using data from DFT (Density Functional Theory) calculations. We investigate under which conditions high spin polarization and significant ION/IOFF ratio, two essential requirements for the spin-MOSFET operation, are both achieved. We show that these particular Heusler channels, in their bulk form, do not have adequate bandgap to provide high ION/IOFF ratios and have small magnetoconductance compared to state-of-the-art devices. However, with confinement into ultra-narrow sizes down to a few nanometers, and by engineering their spin dependent contact resistances, they could prove promising channel materials for the realization of spin-MOSFET transistor devices that offer combined logic and memory functionalities. Although the main compounds of interest in this paper are Mn2CoAl, CrVZrAl, CoVZrAl, and NiFe2O4 alone, we expect that the insight we provide is relevant to other classes of such materials as well.

  11. Low noise control valve

    International Nuclear Information System (INIS)

    Christie, R.S.

    1975-01-01

    Noise is one of the problems associated with the use of any type of control valve in systems involving the flow of fluids. The advent of OSHA standards has prompted control valve manufacturers to design valves with special trim to lower the sound pressure level to meet these standards. However, these levels are in some cases too high, particularly when a valve must be located in or near an area where people are working at tasks requiring a high degree of concentration. Such locations are found around and near research devices and in laboratory-office areas. This paper describes a type of fluid control device presently being used at PPL as a bypass control valve in deionized water systems and designed to reduce sound pressure levels considerably below OSHA standards. Details of the design and construction of this constant pressure drop variable flow control valve are contained in the text and are shown in photographs and drawings. Test data taken are included

  12. Shot noise of spin current and spin transfer torque

    Science.gov (United States)

    Yu, Yunjin; Zhan, Hongxin; Wan, Langhui; Wang, Bin; Wei, Yadong; Sun, Qingfeng; Wang, Jian

    2013-04-01

    We report the theoretical investigation of the shot noise of the spin current (Sσ) and the spin transfer torque (Sτ) for non-collinear spin polarized transport in a spin-valve device which consists of a normal scattering region connected by two ferromagnetic electrodes (MNM system). Our theory was developed using the non-equilibrium Green’s function method, and general nonlinear Sσ - V and Sτ - V relations were derived as a function of the angle θ between the magnetizations of two leads. We have applied our theory to a quantum dot system with a resonant level coupled with two ferromagnetic electrodes. It was found that, for the MNM system, the auto-correlation of the spin current is enough to characterize the fluctuation of the spin current. For a system with three ferromagnetic layers, however, both auto-correlation and cross-correlation of the spin current are needed to characterize the noise of the spin current. For a quantum dot with a resonant level, the derivative of spin torque with respect to bias voltage is proportional to sinθ when the system is far away from resonance. When the system is near resonance, the spin transfer torque becomes a non-sinusoidal function of θ. The derivative of the noise of the spin transfer torque with respect to the bias voltage Nτ behaves differently when the system is near or far away from resonance. Specifically, the differential shot noise of the spin transfer torque Nτ is a concave function of θ near resonance while it becomes a convex function of θ far away from resonance. For certain bias voltages, the period Nτ(θ) becomes π instead of 2π. For small θ, it was found that the differential shot noise of the spin transfer torque is very sensitive to the bias voltage and the other system parameters.

  13. Shot noise of spin current and spin transfer torque

    International Nuclear Information System (INIS)

    Yu Yunjin; Zhan Hongxin; Wan Langhui; Wang Bin; Wei Yadong; Sun Qingfeng; Wang Jian

    2013-01-01

    We report the theoretical investigation of the shot noise of the spin current (S σ ) and the spin transfer torque (S τ ) for non-collinear spin polarized transport in a spin-valve device which consists of a normal scattering region connected by two ferromagnetic electrodes (MNM system). Our theory was developed using the non-equilibrium Green’s function method, and general nonlinear S σ − V and S τ − V relations were derived as a function of the angle θ between the magnetizations of two leads. We have applied our theory to a quantum dot system with a resonant level coupled with two ferromagnetic electrodes. It was found that, for the MNM system, the auto-correlation of the spin current is enough to characterize the fluctuation of the spin current. For a system with three ferromagnetic layers, however, both auto-correlation and cross-correlation of the spin current are needed to characterize the noise of the spin current. For a quantum dot with a resonant level, the derivative of spin torque with respect to bias voltage is proportional to sinθ when the system is far away from resonance. When the system is near resonance, the spin transfer torque becomes a non-sinusoidal function of θ. The derivative of the noise of the spin transfer torque with respect to the bias voltage N τ behaves differently when the system is near or far away from resonance. Specifically, the differential shot noise of the spin transfer torque N τ is a concave function of θ near resonance while it becomes a convex function of θ far away from resonance. For certain bias voltages, the period N τ (θ) becomes π instead of 2π. For small θ, it was found that the differential shot noise of the spin transfer torque is very sensitive to the bias voltage and the other system parameters. (paper)

  14. 241-AN-A valve pit manifold valves and position indication acceptance test procedure

    Energy Technology Data Exchange (ETDEWEB)

    VANDYKE, D.W.

    1999-08-25

    This document describes the method used to test design criteria for gear actuated ball valves installed in 241-AN-A Valve Pit located at 200E Tank Farms. The purpose of this procedure is to demonstrate the following: Equipment is properly installed, labeled, and documented on As-Built drawings; New Manifold Valves in the 241-AN-A Valve Pit are fully operable using the handwheel of the valve operators; New valve position indicators on the valve operators will show correct valve positions; New valve position switches will function properly; and New valve locking devices function properly.

  15. Exchange bias mechanism in FM/FM/AF spin valve systems in the presence of random unidirectional anisotropy field at the AF interface: The role played by the interface roughness due to randomness

    Science.gov (United States)

    Yüksel, Yusuf

    2018-05-01

    We propose an atomistic model and present Monte Carlo simulation results regarding the influence of FM/AF interface structure on the hysteresis mechanism and exchange bias behavior for a spin valve type FM/FM/AF magnetic junction. We simulate perfectly flat and roughened interface structures both with uncompensated interfacial AF moments. In order to simulate rough interface effect, we introduce the concept of random exchange anisotropy field induced at the interface, and acting on the interface AF spins. Our results yield that different types of the random field distributions of anisotropy field may lead to different behavior of exchange bias.

  16. Room-temperature spintronic effects in Alq3-based hybrid devices

    NARCIS (Netherlands)

    Dediu, V.; Hueso, L.E.; Bergenti, I; Riminucci, A.; Borgatti, F.; Graziosi, P.; Newby, C.; Casoli, F.; de Jong, Machiel Pieter; Taliani, C.; Zhan, Y.

    2008-01-01

    We report on efficient spin polarized injection and transport in long 102 nm channels of Alq3 organic semiconductor. We employ vertical spin valve devices with a direct interface between the bottom manganite electrode and Alq3, while the top-electrode geometry consists of an insulating tunnel

  17. Spin valve-like magnetic tunnel diode exhibiting giant positive junction magnetoresistance at low temperature in Co2MnSi/SiO2/p-Si heterostructure

    Science.gov (United States)

    Maji, Nilay; Kar, Uddipta; Nath, T. K.

    2018-02-01

    The rectifying magnetic tunnel diode has been fabricated by growing Co2MnSi (CMS) Heusler alloy film carefully on a properly cleaned p-Si (100) substrate with the help of electron beam physical vapor deposition technique and its structural, electrical and magnetic properties have been experimentally investigated in details. The electronic- and magneto-transport properties at various isothermal conditions have been studied in the temperature regime of 78-300 K. The current-voltage ( I- V) characteristics of the junction show an excellent rectifying magnetic tunnel diode-like behavior throughout that temperature regime. The current ( I) across the junction has been found to decrease with the application of a magnetic field parallel to the plane of the CMS film clearly indicating positive junction magnetoresistance (JMR) of the heterostructure. When forward dc bias is applied to the heterostructure, the I- V characteristics are highly influenced on turning on the field B = 0.5 T at 78 K, and the forward current reduces abruptly (99.2% current reduction at 3 V) which is nearly equal to the order of the magnitude of the current observed in the reverse bias. Hence, our Co2MnSi/SiO2/p-Si heterostructure can perform in off ( I off)/on ( I on) states with the application of non-zero/zero magnetic field like a spin valve at low temperature (78 K).

  18. Structure and magnetoresistive properties of current-perpendicular-to-plane pseudo-spin valves using polycrystalline Co2Fe-based Heusler alloy films

    International Nuclear Information System (INIS)

    Nakatani, T.M.; Du, Ye; Takahashi, Y.K.; Furubayashi, T.; Hono, K.

    2013-01-01

    We report current-perpendicular-to-plane giant magnetoresistance (CPP–GMR) of pseudo-spin valves (PSVs) with polycrystalline Co 2 Fe(Al 0.5 Si 0.5 ) (CFAS) and Co 2 Fe(Ga 0.5 Ge 0.5 ) (CFGG) Heusler alloy films. Strongly [0 1 1] textured polycrystalline Heusler alloy films grew on the Ta/Ru/Ag underlayer. Relatively large CPP–GMR values of ΔRA up to 4 mΩ μm 2 and ΔR/R up to 10% were obtained with 5 nm thick Heusler alloy films and Ag spacer layer by annealing CFAS PSV at 450 °C and CFGG PSV at 350 °C. Transmission electron microscopy revealed a flat and sharp interface between the [0 1 1] textured CFAS layers and the [1 1 1] textured Ag spacer layer. Annealing above an optimal temperature for each PSV led to reductions in MR values as a result of the thickening of the spacer layer induced by the Ag diffusion from the outer Ag layers

  19. Heart valve surgery

    Science.gov (United States)

    ... replacement; Valve repair; Heart valve prosthesis; Mechanical valves; Prosthetic valves ... surgery. Your heart valve has been damaged by infection ( endocarditis ). You have received a new heart valve ...

  20. Effect of NiAl underlayer and spacer on magnetoresistance of current-perpendicular-to-plane spin valves using Co2Mn(Ga0.5Sn0.5) Heusler alloy

    International Nuclear Information System (INIS)

    Hase, N.; Nakatani, T.M.; Kasai, S.; Takahashi, Y.K.; Furubayashi, T.; Hono, K.

    2012-01-01

    We investigated the effect of a NiAl underlayer and spacer on magnetoresistive (MR) properties in current-perpendicular-to-plane spin valves (CPP-SVs) using Co 2 Mn(Ga 0.5 Sn 0.5 ) (CMGS) Heusler alloy ferromagnetic layers. The usage of a NiAl underlayer allowed a high temperature annealing for the L2 1 ordering of the bottom CMGS layer, giving rise to a MR ratio of 10.2% at room temperature. We found that the usage of a NiAl spacer layer also improved the tolerance of the multilayer structure against thermal delamination, which allowed annealing to induce the L2 1 structure in both the bottom and top CMGS layers. However, the short spin diffusion length of NiAl resulted in a lower MR ratio compared to that obtained using a Ag spacer. Transmission electron microscopy of the multilayer structure of CPP-SVs showed that the atomically flat layered structure was maintained after the annealing. - Highlights: → CPP spin valves using Co 2 Mn(Ga 0.5 Sn 0.5 ) ferromagnetic layers with a new underlayer material. → NiAl underlayer and spacer improve the thermal tolerance of the spin valve structure. → NiAl underlayer improves MR ratio compared to Ag because of higher annealing temperature. → NiAl spacer degrades MR ratios compared to Ag because of short spin diffusion length. → Potential of heat resistant underlayer and spacer layer for CPP-SV using Heusler alloy.

  1. Ultrathin Epitaxial Ferromagneticγ-Fe2O3Layer as High Efficiency Spin Filtering Materials for Spintronics Device Based on Semiconductors

    KAUST Repository

    Li, Peng

    2016-06-01

    In spintronics, identifying an effective technique for generating spin-polarized current has fundamental importance. The spin-filtering effect across a ferromagnetic insulating layer originates from unequal tunneling barrier heights for spin-up and spin-down electrons, which has shown great promise for use in different ferromagnetic materials. However, the low spin-filtering efficiency in some materials can be ascribed partially to the difficulty in fabricating high-quality thin film with high Curie temperature and/or partially to the improper model used to extract the spin-filtering efficiency. In this work, a new technique is successfully developed to fabricate high quality, ferrimagnetic insulating γ-Fe2O3 films as spin filter. To extract the spin-filtering effect of γ-Fe2O3 films more accurately, a new model is proposed based on Fowler–Nordheim tunneling and Zeeman effect to obtain the spin polarization of the tunneling currents. Spin polarization of the tunneled current can be as high as −94.3% at 2 K in γ-Fe2O3 layer with 6.5 nm thick, and the spin polarization decays monotonically with temperature. Although the spin-filter effect is not very high at room temperature, this work demonstrates that spinel ferrites are very promising materials for spin injection into semiconductors at low temperature, which is important for development of novel spintronics devices. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

  2. Maximum magnitude in bias-dependent spin accumulation signals of CoFe/MgO/Si on insulator devices

    International Nuclear Information System (INIS)

    Ishikawa, M.; Sugiyama, H.; Inokuchi, T.; Tanamoto, T.; Saito, Y.; Hamaya, K.; Tezuka, N.

    2013-01-01

    We study in detail how the bias voltage (V bias ) and interface resistance (RA) depend on the magnitude of spin accumulation signals (|ΔV| or |ΔV|/I, where I is current) as detected by three-terminal Hanle measurements in CoFe/MgO/Si on insulator (SOI) devices with various MgO layer thicknesses and SOI carrier densities. We find the apparent maximum magnitude of spin polarization as a function of V bias and the correlation between the magnitude of spin accumulation signals and the shape of differential conductance (dI/dV) curves within the framework of the standard spin diffusion model. All of the experimental results can be explained by taking into account the density of states (DOS) in CoFe under the influence of the applied V bias and the quality of MgO tunnel barrier. These results indicate that it is important to consider the DOS of the ferromagnetic materials under the influence of an applied V bias and the quality of tunnel barrier when observing large spin accumulation signals in Si

  3. Valve Disease

    Science.gov (United States)

    ... blood. There are 4 valves in the heart: tricuspid, pulmonary, mitral, and aortic. Two types of problems can disrupt blood flow through the valves: regurgitation or stenosis. Regurgitation is also called insufficiency or incompetence. Regurgitation happens when a valve doesn’ ...

  4. Developments in mechanical heart valve prosthesis

    Indian Academy of Sciences (India)

    Artificial heart valves are engineered devices used for replacing diseased or damaged natural valves of the heart. Most commonly used for replacement are mechanical heart valves and biological valves. This paper briefly outlines the evolution, designs employed, materials being used,. and important factors that affect the ...

  5. Zero-field precession and hysteretic threshold currents in a spin torque nano device with tilted polarizer

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Yan; Bonetti, S; Zha, C L; Akerman, Johan [Department of Microelectronics and Applied Physics, Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden)], E-mail: zhouyan@kth.se

    2009-10-15

    Using nonlinear system theory and numerical simulations, we map out the static and dynamic phase diagrams in the zero applied field of a spin torque nano device with a tilted polarizer (TP). We find that for sufficiently large currents, even very small tilt angles ({beta}>1 deg.) will lead to steady free layer precession in zero field. Within a rather large range of tilt angles, 1 deg. <{beta}<19 deg., we find coexisting static states and hysteretic switching between these using only current. In a more narrow window (1 deg. <{beta}<5 deg.) one of the static states turns into a limit cycle (precession). The coexistence of current-driven static and dynamic states in the zero magnetic field is unique to the TP device and leads to large hysteresis in the upper and lower threshold currents for its operation. The nano device with TP can facilitate the generation of large amplitude mode of spin torque signals without the need for cumbersome magnetic field sources and thus should be very important for future telecommunication applications based on spin transfer torque effects.

  6. Density-controllable nonvolatile memory devices having metal nanocrystals through chemical synthesis and assembled by spin-coating technique

    International Nuclear Information System (INIS)

    Wang Guangli; Chen Yubin; Shi Yi; Pu Lin; Pan Lijia; Zhang Rong; Zheng Youdou

    2010-01-01

    A novel two-step method is employed, for the first time, to fabricate nonvolatile memory devices that have metal nanocrystals. First, size-averaged Au nanocrystals are synthesized chemically; second, they are assembled into memory devices by a spin-coating technique at room temperature. This attractive approach makes it possible to tailor the diameter and control the density of nanocrystals individually. In addition, processes at room temperature prevent Au diffusion, which is a main concern for the application of metal nanocrystal-based memory. The experimental results, both the morphology characterization and the electrical measurements, reveal that there is an optimum density of nanocrystal monolayer to balance between long data retention and a large hysteresis memory window. At the same time, density-controllable devices could also feed the preferential emphasis on either memory window or retention time. All these facts confirm the advantages and novelty of our two-step method. (semiconductor devices)

  7. Conduction Abnormalities and Permanent Pacemaker Implantation After Transcatheter Aortic Valve Replacement Using the Repositionable LOTUS Device: The United Kingdom Experience.

    Science.gov (United States)

    Rampat, Rajiv; Khawaja, M Zeeshan; Hilling-Smith, Roland; Byrne, Jonathan; MacCarthy, Philip; Blackman, Daniel J; Krishnamurthy, Arvindra; Gunarathne, Ashan; Kovac, Jan; Banning, Adrian; Kharbanda, Raj; Firoozi, Sami; Brecker, Stephen; Redwood, Simon; Bapat, Vinayak; Mullen, Michael; Aggarwal, Suneil; Manoharan, Ganesh; Spence, Mark S; Khogali, Saib; Dooley, Maureen; Cockburn, James; de Belder, Adam; Trivedi, Uday; Hildick-Smith, David

    2017-06-26

    The authors report the incidence of pacemaker implantation up to hospital discharge and the factors influencing pacing rate following implantation of the LOTUS bioprosthesis (Boston Scientific, Natick, Massachusetts) in the United Kingdom. Transcatheter aortic valve replacement (TAVR) is associated with a significant need for permanent pacemaker implantation. Pacing rates vary according to the device used. The REPRISE II (Repositionable Percutaneous Replacement of Stenotic Aortic Valve Through Implantation of Lotus Valve System) trial reported a pacing rate of 29% at 30 days after implantation of the LOTUS device. Data were collected retrospectively on 228 patients who had the LOTUS device implanted between March 2013 and February 2015 across 10 centers in the United Kingdom. Twenty-seven patients (12%) had pacemakers implanted pre-procedure and were excluded from the analysis. Patients were aged 81.2 ± 7.7 years; 50.7% were male. The mean pre-procedural QRS duration was 101.7 ± 20.4 ms. More than one-half of the cohort (n = 111, 55%) developed new left bundle branch block (LBBB) following the procedure. Permanent pacemakers were implanted in 64 patients (32%) with a median time to insertion of 3.0 ± 3.4 days. Chief indications for pacing were atrioventricular (AV) block (n = 46, 72%), or LBBB with 1st degree AV block (n = 11, 17%). Amongst those who received a pacemaker following TAVR the pre-procedural electrocardiogram findings included: No conduction disturbance (n = 41, 64%); 1st degree AV block (n = 10, 16%); right bundle branch block (n = 6, 9%) and LBBB (n = 5, 8%). LBBB (but not permanent pacemaker) occurred more frequently in patients who had balloon aortic valvuloplasty before TAVR (odds ratio [OR]: 1.25; p = 0.03). Pre-procedural conduction abnormality (composite of 1st degree AV block, hemiblock, right bundle branch block, LBBB) was independently associated with the need for permanent pacemaker (OR: 2.54; p = 0.048). The absence of

  8. Components for containment enclosures. Part 4: Ventilation and gas-cleaning systems such as filters, traps, safety and regulation valves, control and protection devices

    International Nuclear Information System (INIS)

    2001-01-01

    ISO 11933 consists of the following parts, under the general title Components for containment enclosures: Part 1: Glove/bag ports, bungs for glove/bag ports, enclosure rings and interchangeable units; Part 2: Gloves, welded bags, gaiters for remote-handling tongs and for manipulators; Part 3: Transfer systems such as plain doors, airlock chambers, double door transfer systems, leaktight connections for waste drums; Part 4: Ventilation and gas-cleaning systems such as filters, traps, safety and regulation valves, control and protection devices; Part 5: Penetrations for electrical and fluid circuits. This part of ISO 11933 specifies the design criteria and the characteristics of various components used for ventilation and gas-cleaning in containment enclosures. These components are either directly fixed to the containment enclosure wall, or used in the environment of a shielded or unshielded containment enclosure or line of such enclosures. They can be used alone or in conjunction with other mechanical components, including those specified in ISO 11933-1 and ISO 11933-3. This part of ISO 11933 is applicable to: filtering devices, including high-efficiency particulate air (HEPA) filters and iodine traps; safety valves and pressure regulators; systems ensuring the mechanical protection of containment enclosures; control and pressure-measurement devices

  9. Direct observation of the spin-dependent Peltier effect.

    Science.gov (United States)

    Flipse, J; Bakker, F L; Slachter, A; Dejene, F K; van Wees, B J

    2012-02-05

    The Peltier coefficient describes the amount of heat that is carried by an electrical current when it passes through a material. When two materials with different Peltier coefficients are placed in contact with one another, the Peltier effect causes a net flow of heat either towards or away from the interface between them. Spintronics describes the transport of electric charge and spin angular momentum by separate spin-up and spin-down channels in a device. The observation that spin-up and spin-down charge transport channels are able to transport heat independently of each other has raised the possibility that spin currents could be used to heat or cool the interface between materials with different spin-dependent Peltier coefficients. Here, we report the direct observation of the heating and cooling of such an interface by a spin current. We demonstrate this spin-dependent Peltier effect in a spin-valve pillar structure that consists of two ferromagnetic layers separated by a non-ferromagnetic metal. Using a three-dimensional finite-element model, we extract spin-dependent Peltier coefficients in the range -0.9 to -1.3 mV for permalloy. The magnetic control of heat flow could prove useful for the cooling of nanoscale electronic components or devices.

  10. The effect of output-input isolation on the scaling and energy consumption of all-spin logic devices

    International Nuclear Information System (INIS)

    Hu, Jiaxi; Haratipour, Nazila; Koester, Steven J.

    2015-01-01

    All-spin logic (ASL) is a novel approach for digital logic applications wherein spin is used as the state variable instead of charge. One of the challenges in realizing a practical ASL system is the need to ensure non-reciprocity, meaning the information flows from input to output, not vice versa. One approach described previously, is to introduce an asymmetric ground contact, and while this approach was shown to be effective, it remains unclear as to the optimal approach for achieving non-reciprocity in ASL. In this study, we quantitatively analyze techniques to achieve non-reciprocity in ASL devices, and we specifically compare the effect of using asymmetric ground position and dipole-coupled output/input isolation. For this analysis, we simulate the switching dynamics of multiple-stage logic devices with FePt and FePd perpendicular magnetic anisotropy materials using a combination of a matrix-based spin circuit model coupled to the Landau–Lifshitz–Gilbert equation. The dipole field is included in this model and can act as both a desirable means of coupling magnets and a source of noise. The dynamic energy consumption has been calculated for these schemes, as a function of input/output magnet separation, and the results show that using a scheme that electrically isolates logic stages produces superior non-reciprocity, thus allowing both improved scaling and reduced energy consumption

  11. The effect of output-input isolation on the scaling and energy consumption of all-spin logic devices

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Jiaxi; Haratipour, Nazila; Koester, Steven J., E-mail: skoester@umn.edu [Department of Electrical and Computer Engineering, University of Minnesota-Twin Cities, 200 Union St. SE, Minneapolis, Minnesota 55455 (United States)

    2015-05-07

    All-spin logic (ASL) is a novel approach for digital logic applications wherein spin is used as the state variable instead of charge. One of the challenges in realizing a practical ASL system is the need to ensure non-reciprocity, meaning the information flows from input to output, not vice versa. One approach described previously, is to introduce an asymmetric ground contact, and while this approach was shown to be effective, it remains unclear as to the optimal approach for achieving non-reciprocity in ASL. In this study, we quantitatively analyze techniques to achieve non-reciprocity in ASL devices, and we specifically compare the effect of using asymmetric ground position and dipole-coupled output/input isolation. For this analysis, we simulate the switching dynamics of multiple-stage logic devices with FePt and FePd perpendicular magnetic anisotropy materials using a combination of a matrix-based spin circuit model coupled to the Landau–Lifshitz–Gilbert equation. The dipole field is included in this model and can act as both a desirable means of coupling magnets and a source of noise. The dynamic energy consumption has been calculated for these schemes, as a function of input/output magnet separation, and the results show that using a scheme that electrically isolates logic stages produces superior non-reciprocity, thus allowing both improved scaling and reduced energy consumption.

  12. Tight valve

    International Nuclear Information System (INIS)

    Guedj, F.

    1987-01-01

    This sealed valve is made with a valve seat, an axial valve with a rod fixed to its upper end, a thick bell surrounding the rod and welded by a thin join on the valve casing, a threated ring screwed onto the upper end of the rod and a magnet or electromagnet rotating the ring outside the bell [fr

  13. Investigation of optical band gap and device parameters of rubrene thin film prepared using spin coating technique

    International Nuclear Information System (INIS)

    Tuğluoğlu, Nihat; Barış, Behzad; Gürel, Hatice; Karadeniz, Serdar; Yüksel, Ömer Faruk

    2014-01-01

    Highlights: • Thin film of rubrene has been deposited by spin coating technique. • The band gap properties of the film were investigated in the range 200–700 nm. • The analysis of the absorption coefficient revealed indirect allowed transition. • The parameters such as barrier height and ideality factor were determined. -- Abstract: Rubrene thin film has been deposited by spin coating technique. The optical band gap properties of rubrene thin film have been investigated in the spectral range 200–700 nm. The results of the absorption coefficient (α) were analyzed in order to determine the optical band gap and Urbach energy of the film. The absorption spectra recorded in the UV–vis region shows two peaks at 250 nm and 300 nm. The analysis of the spectral behavior of the absorption coefficient (α) in the absorption region revealed indirect allowed transition with corresponding energy 2.31 eV. The value of Urbach energy (E U ) was determined to be 1.169 eV. The current–voltage (I–V) characteristics and electrical conduction properties of rubrene/n-Si device fabricated by spin coating method have also been investigated. The I–V characteristic in dark was showed the rectification effect due to the formation of Schottky barrier at rubrene/silicon interface. From analyzing the I-V measurement for the device, the basic device parameters such as barrier height, ideality factor and series resistance were determined. At the low-voltage region, the current conduction in Au/rubrene/n-Si device is ohmic type. The charge transport phenomenon appears to be space charge limited current (SCLC) at higher-voltage regions

  14. Investigation of optical band gap and device parameters of rubrene thin film prepared using spin coating technique

    Energy Technology Data Exchange (ETDEWEB)

    Tuğluoğlu, Nihat, E-mail: tugluo@gmail.com [Department of Technology, Sarayköy Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey); Barış, Behzad; Gürel, Hatice [Department of Physics, Faculty of Arts and Sciences, Giresun University, Gazipaşa Campus, Giresun 28100 (Turkey); Karadeniz, Serdar [Department of Technology, Sarayköy Nuclear Research and Training Center, 06983 Saray, Ankara (Turkey); Yüksel, Ömer Faruk [Department of Physics, Faculty of Science, Selçuk University, Campus Konya 42075 (Turkey)

    2014-01-05

    Highlights: • Thin film of rubrene has been deposited by spin coating technique. • The band gap properties of the film were investigated in the range 200–700 nm. • The analysis of the absorption coefficient revealed indirect allowed transition. • The parameters such as barrier height and ideality factor were determined. -- Abstract: Rubrene thin film has been deposited by spin coating technique. The optical band gap properties of rubrene thin film have been investigated in the spectral range 200–700 nm. The results of the absorption coefficient (α) were analyzed in order to determine the optical band gap and Urbach energy of the film. The absorption spectra recorded in the UV–vis region shows two peaks at 250 nm and 300 nm. The analysis of the spectral behavior of the absorption coefficient (α) in the absorption region revealed indirect allowed transition with corresponding energy 2.31 eV. The value of Urbach energy (E{sub U}) was determined to be 1.169 eV. The current–voltage (I–V) characteristics and electrical conduction properties of rubrene/n-Si device fabricated by spin coating method have also been investigated. The I–V characteristic in dark was showed the rectification effect due to the formation of Schottky barrier at rubrene/silicon interface. From analyzing the I-V measurement for the device, the basic device parameters such as barrier height, ideality factor and series resistance were determined. At the low-voltage region, the current conduction in Au/rubrene/n-Si device is ohmic type. The charge transport phenomenon appears to be space charge limited current (SCLC) at higher-voltage regions.

  15. Determining the spin dependent mean free path in Co90Fe10 using giant magnetoresistance

    Science.gov (United States)

    Shakespear, K. F.; Perdue, K. L.; Moyerman, S. M.; Checkelsky, J. G.; Harberger, S. S.; Tamboli, A. C.; Carey, M. J.; Sparks, P. D.; Eckert, J. C.

    2005-05-01

    The spin dependent mean free path in Co90Fe10 is determined as a function of temperature down to 5K using two different spin valve structures. At 5K the spin dependent mean free path for one structure was measured to be 9.4±1.4nm, decreasing by a factor of 3 by 350K. For the other structure, it is 7.5±0.5nm at 5K and decreased by a factor of 1.5 by 350K. In both cases, the spin dependent mean free path approaches the typical thickness of ferromagnetic layers in spin valves at room temperature and, thus, has an impact on the choice of design parameters for the development of new spintronic devices.

  16. Electrical spin injection and detection in silicon nanowires with axial doping gradient.

    Science.gov (United States)

    Kountouriotis, Konstantinos; Barreda, Jorge L; Keiper, Timothy David; Zhang, Mei; Xiong, Peng

    2018-06-13

    The interest in spin transport in nanoscopic semiconductor channels is driven by both the inevitable miniaturization of spintronics devices toward nanoscale and the rich spin-dependent physics the quantum confinement engenders. For such studies, the all-important issue of the ferromagnet/semiconductor (FM/SC) interface becomes even more critical at nanoscale. Here we elucidate the effects of the FM/SC interface on electrical spin injection and detection at nanoscale dimensions, utilizing a unique type of Si nanowires (NWs) with an inherent axial doping gradient. Two-terminal and nonlocal four-terminal lateral spin-valve measurements were performed using different combinations from a series of FM contacts positioned along the same NW. The data are analyzed with a general model of spin accumulation in a normal channel under electrical spin injection from a FM, which reveals a distinct correlation of decreasing spin-valve signal with increasing injector junction resistance. The observation is attributed to the diminishing contribution of the d-electrons in the FM to the injected current spin polarization with increasing Schottky barrier width. The results demonstrate that there is a window of interface parameters for optimal spin injection efficiency and current spin polarization, which provides important design guidelines for nano-spintronic devices with quasi-1D semiconductor channels.

  17. Annealing-temperature-dependent voltage-sign reversal in all-oxide spin Seebeck devices using RuO2

    Science.gov (United States)

    Kirihara, Akihiro; Ishida, Masahiko; Yuge, Ryota; Ihara, Kazuki; Iwasaki, Yuma; Sawada, Ryohto; Someya, Hiroko; Iguchi, Ryo; Uchida, Ken-ichi; Saitoh, Eiji; Yorozu, Shinichi

    2018-04-01

    Thermoelectric converters based on the spin Seebeck effect (SSE) have attracted great attention due to their potential to offer novel applications such as energy harvesting and heat-flow sensing. For converting a SSE-induced spin current into an electric current, a transition metal film such as Pt, which exhibits large inverse spin-Hall effect (ISHE), has been typically used. In this work, we show an all-oxide SSE device using ruthenium oxide (RuO2) as a conductive film. We found that both the sign and magnitude of the SSE-induced ISHE voltage V appearing in the RuO2 film changes depending on the post annealing temperature, and that the magnitude can become larger than that of a standard SSE device using Pt. The similar sign change was also observed in Hall-resistance measurements of the RuO2 films. X-ray absorption fine structure (XAFS) spectra of as-deposited and annealed RuO2 revealed that the annealing process substantially improved the long-range crystalline order in RuO2. This suggests that change in the crystalline order may modify the dominant ISHE mechanism or electronic states in RuO2, leading to the sign reversal of V as well as the Hall coefficient. Our result demonstrates that RuO2 is an interesting material not only as a practical ISHE film but also as a testbed to study physics of spin-to-charge converters that depend on their crystalline order.

  18. The spin-dependent electronic transport properties of M(dcdmp)2 (M = Cu, Au, Co, Ni) molecular devices based on zigzag graphene nanoribbon electrodes

    Science.gov (United States)

    Li, Dongde; Wu, Di; Zhang, Xiaojiao; Zeng, Bowen; Li, Mingjun; Duan, Haiming; Yang, Bingchu; Long, Mengqiu

    2018-05-01

    The spin-dependent electronic transport properties of M(dcdmp)2 (M = Cu, Au, Co, Ni; dcdmp = 2,3-dicyano-5,6-dimercaptopyrazyne) molecular devices based on zigzag graphene nanoribbon (ZGNR) electrodes were investigated by density functional theory combined nonequilibrium Green's function method (DFT-NEGF). Our results show that the spin-dependent transport properties of the M(dcdmp)2 molecular devices can be controlled by the spin configurations of the ZGNR electrodes, and the central 3d-transition metal atom can introduce a larger magnetism than that of the nonferrous metal one. Moreover, the perfect spin filtering effect, negative differential resistance, rectifying effect and magnetic resistance phenomena can be observed in our proposed M(dcdmp)2 molecular devices.

  19. Influence of spin methods on the performance of polymer light-emitting devices

    International Nuclear Information System (INIS)

    Liu Chen; Zou Xuecheng; Yin Sheng; Zhang Wuxing

    2004-01-01

    Using the doped polymeric system composed of host poly(N-vinylcarbazole) and dopant coumarin 6, the morphology, phase distribution, and polymer molecular conformation of polymer films were investigated with optical and atomic force microscopy, UV-visible absorption spectra, and Fourier transform infrared reflectance spectroscopy. Results show that the film morphology and dopant distribution in the polymer films cast with the conventional method are dependent on the positions of polymer films. To avoid this negative effect, a new spin method was put forward by locating the specimen at an appropriate distance from the center of the spin plate during spin casting. It is found that polymer films prepared with the new method are more uniform and their electroluminescence performances are independent of the positions

  20. Half metallic ferromagnet Pr_0_._9_5Mn_0_._9_3_9O_3 for spin based devices

    International Nuclear Information System (INIS)

    Santhosh Kumar, B.; Praveen Shankar, N.; Venkateswaran, C.; Manimuthu, P.

    2016-01-01

    Half Metallic Ferromagnets (HMF) are excellent candidates for spintronics devices due to their unusual 3d and 4s bands. Band theory and first principles calculations strongly predict that Pr based compounds are promising HMF candidates due to their spin hybridisation. Among all Pr based HMF, Pr_0_._9_5Mn_0_._9_3_9O_3 is special because of its pervoskite structure. The different oxidation states of Mn and Pr will enhance the hybridisation of 3d and 4f bands. The present study is experimental effort on the preparation of Pr based compounds

  1. Check valve

    Science.gov (United States)

    Upton, H.A.; Garcia, P.

    1999-08-24

    A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion. 5 figs.

  2. Check valve

    International Nuclear Information System (INIS)

    Upton, H.A.; Garcia, P.

    1999-01-01

    A check valve for use in a GDCS of a nuclear reactor and having a motor driven disk including a rotatable armature for rotating the check valve disk over its entire range of motion is described. In one embodiment, the check valve includes a valve body having a coolant flow channel extending therethrough. The coolant flow channel includes an inlet end and an outlet end. A valve body seat is located on an inner surface of the valve body. The check valve further includes a disk assembly, sometimes referred to as the motor driven disc, having a counterweight and a disk shaped valve. The disk valve includes a disk base having a seat for seating with the valve body seat. The disk assembly further includes a first hinge pin member which extends at least partially through the disk assembly and is engaged to the disk. The disk valve is rotatable relative to the first hinge pin member. The check valve also includes a motor having a stator frame with a stator bore therein. An armature is rotatably positioned within the stator bore and the armature is coupled to the disk valve to cause the disk valve to rotate about its full range of motion. 5 figs

  3. The phase accumulation and antenna near field of microscopic propagating spin wave devices

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Crosby S.; Kostylev, Mikhail, E-mail: mikhail.kostylev@uwa.edu.au; Ivanov, Eugene [School of Physics M013, The University of Western Australia, Crawley, WA 6009 (Australia); Ding, Junjia; Adeyeye, Adekunle O. [Department of Electrical and Computer Engineering, National University of Singapore, 117576 Singapore (Singapore)

    2014-01-20

    We studied phase accumulation by the highly non-reciprocal magnetostatic surface spin waves in thin Permalloy microstripes excited and received by microscopic coplanar antennae. We find that the experimentally measured characteristic length of the near field of the antenna is smaller than the total width of the coplanar. This is confirmed by our numerical simulations. Consequently, the distance over which the spin wave accumulates its phase while travelling between the input and output antennae coincides with the distance between the antennae symmetry axes with good accuracy.

  4. The phase accumulation and antenna near field of microscopic propagating spin wave devices

    International Nuclear Information System (INIS)

    Chang, Crosby S.; Kostylev, Mikhail; Ivanov, Eugene; Ding, Junjia; Adeyeye, Adekunle O.

    2014-01-01

    We studied phase accumulation by the highly non-reciprocal magnetostatic surface spin waves in thin Permalloy microstripes excited and received by microscopic coplanar antennae. We find that the experimentally measured characteristic length of the near field of the antenna is smaller than the total width of the coplanar. This is confirmed by our numerical simulations. Consequently, the distance over which the spin wave accumulates its phase while travelling between the input and output antennae coincides with the distance between the antennae symmetry axes with good accuracy

  5. Circuit Simulation of All-Spin Logic

    KAUST Repository

    Alawein, Meshal

    2016-05-01

    With the aggressive scaling of complementary metal-oxide semiconductor (CMOS) nearing an inevitable physical limit and its well-known power crisis, the quest for an alternative/augmenting technology that surpasses the current semiconductor electronics is needed for further technological progress. Spintronic devices emerge as prime candidates for Beyond CMOS era by utilizing the electron spin as an extra degree of freedom to decrease the power consumption and overcome the velocity limit connected with the charge. By using the nonvolatility nature of magnetization along with its direction to represent a bit of information and then manipulating it by spin-polarized currents, routes are opened for combined memory and logic. This would not have been possible without the recent discoveries in the physics of nanomagnetism such as spin-transfer torque (STT) whereby a spin-polarized current can excite magnetization dynamics through the transfer of spin angular momentum. STT have expanded the available means of switching the magnetization of magnetic layers beyond old classical techniques, promising to fulfill the need for a new generation of dense, fast, and nonvolatile logic and storage devices. All-spin logic (ASL) is among the most promising spintronic logic switches due to its low power consumption, logic-in-memory structure, and operation on pure spin currents. The device is based on a lateral nonlocal spin valve and STT switching. It utilizes two nanomagnets (whereby information is stored) that communicate with pure spin currents through a spin-coherent nonmagnetic channel. By using the well-known spin physics and the recently proposed four-component spin circuit formalism, ASL can be thoroughly studied and simulated. Previous attempts to model ASL in the linear and diffusive regime either neglect the dynamic characteristics of transport or do not provide a scalable and robust platform for full micromagnetic simulations and inclusion of other effects like spin Hall

  6. Devices and process for high-pressure magic angle spinning nuclear magnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Hoyt, David W.; Sears, Jesse A.; Turcu, Romulus V. F.; Rosso, Kevin M.; Hu, Jian Zhi

    2017-12-05

    A high-pressure magic angle spinning (MAS) rotor is detailed that includes a high-pressure sample cell that maintains high pressures exceeding 150 bar. The sample cell design minimizes pressure losses due to penetration over an extended period of time.

  7. Spin and charge transport in graphene devices in the classical and quantum regimes

    NARCIS (Netherlands)

    Diniz Guimaraes, Marcos Henrique

    2015-01-01

    Grafeen, één atoom dik koolstofmateriaal, werd in het afgelopen decennium één van de meest veelbelovende materialen voor toekomstige elektronische apparaten. Grafeen heeft ook groot potentieel getoond voor spintronische toepassingen, waarbij het intrinsieke hoekmoment van het elektron (spin) wordt

  8. Another spin in the wall : domain wall dynamics in perpendicularly magnetized devices

    NARCIS (Netherlands)

    Lavrijsen, R.

    2011-01-01

    The world as we know it today would be completely different without spintronics. It has revolutionized the way we carry, store and exchange information in our daily lives. What is it? It is a research realm that combines the fundamental property of the electron, spin, and the charge property driving

  9. In search of a quasi-zero dimensional quantum spin-switching device

    International Nuclear Information System (INIS)

    Hancock, Y.

    2002-01-01

    Full text: In this paper, we propose a theoretical mechanism and potential application for quantum spin switching systems of the generic NMMMMMN type. In this case, N and M respectively refer to non-magnetic and magnetic atoms, of a 7-site finite, inhomogeneous system. We base our understanding on recent investigations into the magnetic induction mechanism on the N-type sites. Such investigations were performed within the context of the Hubbard Model, using both Hartree-Fock and Exact Diagonalization studies. In this work, we have used exact diagonalization studies to probe the spin-spin (2-site) correlation results of these systems, as a function of the model parameters and electron filling. Such calculations were performed within the context of the Hubbard and the Extended Hubbard Models. We have used our results as a means of investigating the proposed quantum spin-switching mechanism within the context of the full many-body problem. In addition to investigating this mechanism, we aim to propose a more realistic theoretical context in which the potential of these systems can be further explored

  10. Devices and process for high-pressure magic angle spinning nuclear magnetic resonance

    Science.gov (United States)

    Hoyt, David W; Sears, Jr., Jesse A; Turcu, Romulus V.F.; Rosso, Kevin M; Hu, Jian Zhi

    2014-04-08

    A high-pressure magic angle spinning (MAS) rotor is detailed that includes a high-pressure sample cell that maintains high pressures exceeding 150 bar. The sample cell design minimizes pressure losses due to penetration over an extended period of time.

  11. Magnetic Nanostructures Spin Dynamics and Spin Transport

    CERN Document Server

    Farle, Michael

    2013-01-01

    Nanomagnetism and spintronics is a rapidly expanding and increasingly important field of research with many applications already on the market and many more to be expected in the near future. This field started in the mid-1980s with the discovery of the GMR effect, recently awarded with the Nobel prize to Albert Fert and Peter Grünberg. The present volume covers the most important and most timely aspects of magnetic heterostructures, including spin torque effects, spin injection, spin transport, spin fluctuations, proximity effects, and electrical control of spin valves. The chapters are written by internationally recognized experts in their respective fields and provide an overview of the latest status.

  12. Tunneling-Magnetoresistance Ratio Comparison of MgO-Based Perpendicular-Magnetic-Tunneling-Junction Spin Valve Between Top and Bottom Co2Fe6B2 Free Layer Structure.

    Science.gov (United States)

    Lee, Du-Yeong; Lee, Seung-Eun; Shim, Tae-Hun; Park, Jea-Gun

    2016-12-01

    For the perpendicular-magnetic-tunneling-junction (p-MTJ) spin valve with a nanoscale-thick bottom Co2Fe6B2 free layer ex situ annealed at 400 °C, which has been used as a common p-MTJ structure, the Pt atoms of the Pt buffer layer diffused into the MgO tunneling barrier. This transformed the MgO tunneling barrier from a body-centered cubic (b.c.c) crystallized layer into a mixture of b.c.c, face-centered cubic, and amorphous layers and rapidly decreased the tunneling-magnetoresistance (TMR) ratio. The p-MTJ spin valve with a nanoscale-thick top Co2Fe6B2 free layer could prevent the Pt atoms diffusing into the MgO tunneling barrier during ex situ annealing at 400 °C because of non-necessity of a Pt buffer layer, demonstrating the TMR ratio of ~143 %.

  13. A New Experimental Device for Transapical Access of the Aortic and Mitral Valves as well as the Aorta in its Various Segments

    Directory of Open Access Journals (Sweden)

    Leonardo Paim

    Full Text Available Abstract Objective: To present the results of a new experimental device developed to facilitate the transapical access in endovascular treatment of structural heart diseases. It aims to reduce the risk of bleeding and complications in this type of access and demonstrate the device as a safe, fast and effective alternative. Methods: CorPoint is composed of three parts: introducer, base with coiled spring, and closing capsule. By rotating movements, the spring is introduced into the myocardium and progressively approaches the base to the surface of the heart. Guidewires and catheters are inserted through the hollow central part and, at the end of the procedure, the capsule is screwed over the base, therefore stopping any bleeding. Results: The device was implanted in 15 pigs, weighing 60 kg each, through an anterolateral thoracotomy, while catheters were introduced and guided by fluoroscopy. All animals had minimal bleeding; introducers with diameter up to 22 Fr were used and various catheters and guidewires were easily handled. After finishing the procedure, the closing capsule was attached and no bleeding was observed at the site. Conclusion: This new device has proved effective, fast and secure for the transapical access. This shows great potential for use, especially by ensuring an easier and direct access to the mitral and aortic valves; the shortest distance to be traveled by catheters; access to the ascending and descending aorta; decreased bleeding complications; decreased surgical time; and the possibility of allowing the technique to evolve and become totally percutaneous.

  14. Control Valve

    Energy Technology Data Exchange (ETDEWEB)

    Moore, Wayne R.

    2018-03-20

    A control valve includes a first conduit having a first inlet and a first outlet and defining a first passage; a second conduit having a second inlet and a second outlet and defining a second passage, the second conduit extending into the first passage such that the second inlet is located within the first passage; and a valve plate disposed pivotably within the first passage, the valve plate defining a valve plate surface. Pivoting of the valve plate within the first passage varies flow from the first inlet to the first outlet and the valve plate is pivotal between a first position and a second position such that in the first position the valve plate substantially prevents fluid communication between the first passage and the second passage and such that in the second position the valve plate permits fluid communication between the first passage and the second passage.

  15. Influence of surgical implantation angle of left ventricular assist device outflow graft and management of aortic valve opening on the risk of stroke in heart failure patients

    Science.gov (United States)

    Chivukula, V. Keshav; McGah, Patrick; Prisco, Anthony; Beckman, Jennifer; Mokadam, Nanush; Mahr, Claudius; Aliseda, Alberto

    2016-11-01

    Flow in the aortic vasculature may impact stroke risk in patients with left ventricular assist devices (LVAD) due to severely altered hemodynamics. Patient-specific 3D models of the aortic arch and great vessels were created with an LVAD outflow graft at 45, 60 and 90° from centerline of the ascending aorta, in order to understand the effect of surgical placement on hemodynamics and thrombotic risk. Intermittent aortic valve opening (once every five cardiac cycles) was simulated and the impact of this residual native output investigated for the potential to wash out stagnant flow in the aortic root region. Unsteady CFD simulations with patient-specific boundary conditions were performed. Particle tracking for 10 cardiac cycles was used to determine platelet residence times and shear stress histories. Thrombosis risk was assessed by a combination of Eulerian and Lagrangian metrics and a newly developed thrombogenic potential metric. Results show a strong influence of LVAD outflow graft angle on hemodynamics in the ascending aorta and consequently on stroke risk, with a highly positive impact of aortic valve opening, even at low frequencies. Optimization of LVAD implantation and management strategies based on patient-specific simulations to minimize stroke risk will be presented

  16. Valve assembly

    International Nuclear Information System (INIS)

    Sandling, M.

    1981-01-01

    An improved valve assembly, used for controlling the flow of radioactive slurry, is described. Radioactive contamination of the air during removal or replacement of the valve is prevented by sucking air from the atmosphere through a portion of the structure above the valve housing. (U.K.)

  17. Management of severe ischemic cardiomyopathy: left ventricular assist device as destination therapy versus conventional bypass and mitral valve surgery.

    Science.gov (United States)

    Maltais, Simon; Tchantchaleishvili, Vahtang; Schaff, Hartzell V; Daly, Richard C; Suri, Rakesh M; Dearani, Joseph A; Topilsky, Yan; Stulak, John M; Joyce, Lyle D; Park, Soon J

    2014-04-01

    Patients with severe ischemic cardiomyopathy (left ventricular ejection fraction assist device as destination therapy is reserved for patients who are too high risk for conventional surgery. We evaluated our outcomes with conventional surgery within this population and the comparative effectiveness of these 2 therapies. We identified patients who underwent conventional surgery or left ventricular assist device as destination therapy for severe ischemic cardiomyopathy (left ventricular ejection fraction assist device as destination therapy. We compared baseline patient characteristics and outcomes in terms of end-organ function and survival. A total of 88 patients were identified; 55 patients underwent conventional surgery (63%), and 33 patients (37%) received a left ventricular assist device as destination therapy. Patients who received left ventricular assist device as destination therapy had the increased prevalence of renal failure, inotrope dependency, and intra-aortic balloon support. Patients undergoing conventional surgery required longer ventilatory support, and patients receiving a left ventricular assist device required more reoperation for bleeding. Mortality rates were similar between the 2 groups at 30 days (7% in the conventional surgery group vs 3% in the left ventricular assist device as destination therapy group, P = .65) and at 1 year (22% in the conventional surgery group vs 15% in the left ventricular assist device as destination therapy group, P = .58). There was a trend toward improved survival in patients receiving a left ventricular assist device compared with the propensity-matched groups at 1 year (94% vs 71%, P = .171). The operative mortality and early survival after conventional surgery seem to be acceptable. For inoperable or prohibitive-risk patients, left ventricular assist device as destination therapy can be offered with similar outcomes. Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby

  18. Spin electronics

    CERN Document Server

    Buhrman, Robert; Daughton, James; Molnár, Stephan; Roukes, Michael

    2004-01-01

    This report is a comparative review of spin electronics ("spintronics") research and development activities in the United States, Japan, and Western Europe conducted by a panel of leading U.S. experts in the field. It covers materials, fabrication and characterization of magnetic nanostructures, magnetism and spin control in magnetic nanostructures, magneto-optical properties of semiconductors, and magnetoelectronics and devices. The panel's conclusions are based on a literature review and a series of site visits to leading spin electronics research centers in Japan and Western Europe. The panel found that Japan is clearly the world leader in new material synthesis and characterization; it is also a leader in magneto-optical properties of semiconductor devices. Europe is strong in theory pertaining to spin electronics, including injection device structures such as tunneling devices, and band structure predictions of materials properties, and in development of magnetic semiconductors and semiconductor heterost...

  19. Homoepitaxial graphene tunnel barriers for spin transport

    Directory of Open Access Journals (Sweden)

    Adam L. Friedman

    2016-05-01

    Full Text Available Tunnel barriers are key elements for both charge-and spin-based electronics, offering devices with reduced power consumption and new paradigms for information processing. Such devices require mating dissimilar materials, raising issues of heteroepitaxy, interface stability, and electronic states that severely complicate fabrication and compromise performance. Graphene is the perfect tunnel barrier. It is an insulator out-of-plane, possesses a defect-free, linear habit, and is impervious to interdiffusion. Nonetheless, true tunneling between two stacked graphene layers is not possible in environmental conditions usable for electronics applications. However, two stacked graphene layers can be decoupled using chemical functionalization. Here, we demonstrate that hydrogenation or fluorination of graphene can be used to create a tunnel barrier. We demonstrate successful tunneling by measuring non-linear IV curves and a weakly temperature dependent zero-bias resistance. We demonstrate lateral transport of spin currents in non-local spin-valve structures, and determine spin lifetimes with the non-local Hanle effect. We compare the results for hydrogenated and fluorinated tunnel and we discuss the possibility that ferromagnetic moments in the hydrogenated graphene tunnel barrier affect the spin transport of our devices.

  20. Homoepitaxial graphene tunnel barriers for spin transport

    Science.gov (United States)

    Friedman, Adam L.; van't Erve, Olaf M. J.; Robinson, Jeremy T.; Whitener, Keith E.; Jonker, Berend T.

    2016-05-01

    Tunnel barriers are key elements for both charge-and spin-based electronics, offering devices with reduced power consumption and new paradigms for information processing. Such devices require mating dissimilar materials, raising issues of heteroepitaxy, interface stability, and electronic states that severely complicate fabrication and compromise performance. Graphene is the perfect tunnel barrier. It is an insulator out-of-plane, possesses a defect-free, linear habit, and is impervious to interdiffusion. Nonetheless, true tunneling between two stacked graphene layers is not possible in environmental conditions usable for electronics applications. However, two stacked graphene layers can be decoupled using chemical functionalization. Here, we demonstrate that hydrogenation or fluorination of graphene can be used to create a tunnel barrier. We demonstrate successful tunneling by measuring non-linear IV curves and a weakly temperature dependent zero-bias resistance. We demonstrate lateral transport of spin currents in non-local spin-valve structures, and determine spin lifetimes with the non-local Hanle effect. We compare the results for hydrogenated and fluorinated tunnel and we discuss the possibility that ferromagnetic moments in the hydrogenated graphene tunnel barrier affect the spin transport of our devices.

  1. Valve system incorporating single failure protection logic

    Science.gov (United States)

    Ryan, Rodger; Timmerman, Walter J. H.

    1980-01-01

    A valve system incorporating single failure protective logic. The system consists of a valve combination or composite valve which allows actuation or de-actuation of a device such as a hydraulic cylinder or other mechanism, integral with or separate from the valve assembly, by means of three independent input signals combined in a function commonly known as two-out-of-three logic. Using the input signals as independent and redundant actuation/de-actuation signals, a single signal failure, or failure of the corresponding valve or valve set, will neither prevent the desired action, nor cause the undesired action of the mechanism.

  2. Impact of Tricuspid Valve Surgery at the Time of Left Ventricular Assist Device Insertion on Postoperative Outcomes

    OpenAIRE

    Dunlay, Shannon M.; Deo, Salil V.; Park, Soon J.

    2015-01-01

    Tricuspid regurgitation (TR) is common in patients with heart failure undergoing left ventricular assist device (LVAD) implantation. Whether the TR should be surgically managed at the time of LVAD surgery is controversial.

  3. On the use of ultracentrifugal devices for routine sample preparation in biomolecular magic-angle-spinning NMR.

    Science.gov (United States)

    Mandal, Abhishek; Boatz, Jennifer C; Wheeler, Travis B; van der Wel, Patrick C A

    2017-03-01

    A number of recent advances in the field of magic-angle-spinning (MAS) solid-state NMR have enabled its application to a range of biological systems of ever increasing complexity. To retain biological relevance, these samples are increasingly studied in a hydrated state. At the same time, experimental feasibility requires the sample preparation process to attain a high sample concentration within the final MAS rotor. We discuss these considerations, and how they have led to a number of different approaches to MAS NMR sample preparation. We describe our experience of how custom-made (or commercially available) ultracentrifugal devices can facilitate a simple, fast and reliable sample preparation process. A number of groups have since adopted such tools, in some cases to prepare samples for sedimentation-style MAS NMR experiments. Here we argue for a more widespread adoption of their use for routine MAS NMR sample preparation.

  4. On the use of ultracentrifugal devices for routine sample preparation in biomolecular magic-angle-spinning NMR

    Energy Technology Data Exchange (ETDEWEB)

    Mandal, Abhishek; Boatz, Jennifer C. [University of Pittsburgh School of Medicine, Department of Structural Biology (United States); Wheeler, Travis B. [University of Pittsburgh School of Medicine, Department of Cell Biology (United States); Wel, Patrick C. A. van der, E-mail: vanderwel@pitt.edu [University of Pittsburgh School of Medicine, Department of Structural Biology (United States)

    2017-03-15

    A number of recent advances in the field of magic-angle-spinning (MAS) solid-state NMR have enabled its application to a range of biological systems of ever increasing complexity. To retain biological relevance, these samples are increasingly studied in a hydrated state. At the same time, experimental feasibility requires the sample preparation process to attain a high sample concentration within the final MAS rotor. We discuss these considerations, and how they have led to a number of different approaches to MAS NMR sample preparation. We describe our experience of how custom-made (or commercially available) ultracentrifugal devices can facilitate a simple, fast and reliable sample preparation process. A number of groups have since adopted such tools, in some cases to prepare samples for sedimentation-style MAS NMR experiments. Here we argue for a more widespread adoption of their use for routine MAS NMR sample preparation.

  5. Safety and performance of a novel embolic deflection device in patients undergoing transcatheter aortic valve replacement: results from the DEFLECT I study.

    Science.gov (United States)

    Baumbach, Andreas; Mullen, Michael; Brickman, Adam M; Aggarwal, Suneil K; Pietras, Cody G; Forrest, John K; Hildick-Smith, David; Meller, Stephanie M; Gambone, Louise; den Heijer, Peter; Margolis, Pauliina; Voros, Szilard; Lansky, Alexandra J

    2015-05-01

    This study aimed to evaluate the safety and performance of the TriGuard™ Embolic Deflection Device (EDD), a nitinol mesh filter positioned in the aortic arch across all three major cerebral artery take-offs to deflect emboli away from the cerebral circulation, in patients undergoing transcatheter aortic valve replacement (TAVR). The prospective, multicentre DEFLECT I study (NCT01448421) enrolled 37 consecutive subjects undergoing TAVR with the TriGuard EDD. Subjects underwent clinical and cognitive follow-up to 30 days; cerebral diffusion-weighted magnetic resonance imaging (DW-MRI) was performed pre-procedure and at 4±2 days post procedure. The device performed as intended with successful cerebral coverage in 80% (28/35) of cases. The primary safety endpoint (in-hospital EDD device- or EDD procedure-related cardiovascular mortality, major stroke disability, life-threatening bleeding, distal embolisation, major vascular complications, or need for acute cardiac surgery) occurred in 8.1% of subjects (VARC-defined two life-threatening bleeds and one vascular complication). The presence of new cerebral ischaemic lesions on post-procedure DW-MRI (n=28) was similar to historical controls (82% vs. 76%, p=NS). However, an exploratory analysis found that per-patient total lesion volume was 34% lower than reported historical data (0.2 vs. 0.3 cm3), and 89% lower in patients with complete (n=17) versus incomplete (n=10) cerebral vessel coverage (0.05 vs. 0.45 cm3, p=0.016). Use of the first-generation TriGuard EDD during TAVR is safe, and device performance was successful in 80% of cases during the highest embolic-risk portions of the TAVR procedure. The potential of the TriGuard EDD to reduce total cerebral ischaemic burden merits further randomised investigation.

  6. Tuning spin-polarized transport in organic semiconductors

    Science.gov (United States)

    Mattana, Richard; Galbiati, Marta; Delprat, Sophie; Tatay, Sergio; Deranlot, Cyrile; Seneor, Pierre; Petroff, Frederic

    Molecular spintronics is an emerging research field at the frontier between organic chemistry and the spintronics. Compared to traditional inorganic materials molecules are flexible and can be easily tailored by chemical synthesis. Due to their theoretically expected very long spin lifetime, they were first only seen as the ultimate media for spintronics devices. It was recently that new spintronics tailoring could arise from the chemical versatility brought by molecules. The hybridization between a ferromagnet and molecules induces a spin dependent broadening and energy shifting of the molecular orbitals leading to an induced spin polarization on the first molecular layer. This spin dependent hybridization can be used to tailor the spin dependent transport in organic spintronics devices. We have studied vertical Co/Alq3/Co organic spin valves. The negative magnetoresistance observed is the signature of different coupling strengths at the top and bottom interfaces. We have then inserted an inorganic tunnel barrier at the bottom interface in order to suppress the spin-dependent hybridization. In this case we restore a positive magnetoresistance. This demonstrates that at the bottom Co/Alq3 interface a stronger coupling occurs which induces an inversion of the spin polarization.

  7. Spin-polarized transport through single-molecule magnet Mn6 complexes

    KAUST Repository

    Cremades, Eduard; Pemmaraju, C. D.; Sanvito, Stefano; Ruiz, Eliseo

    2013-01-01

    The coherent transport properties of a device, constructed by sandwiching a Mn6 single-molecule magnet between two gold surfaces, are studied theoretically by using the non-equilibrium Green's function approach combined with density functional theory. Two spin states of such Mn6 complexes are explored, namely the ferromagnetically coupled configuration of the six MnIII cations, leading to the S = 12 ground state, and the low S = 4 spin state. For voltages up to 1 volt the S = 12 ground state shows a current one order of magnitude larger than that of the S = 4 state. Furthermore this is almost completely spin-polarized, since the Mn6 frontier molecular orbitals for S = 12 belong to the same spin manifold. As such the high-anisotropy Mn6 molecule appears as a promising candidate for implementing, at the single molecular level, both spin-switches and low-temperature spin-valves. © 2013 The Royal Society of Chemistry.

  8. Fabrication of three-dimensional micro-nanofiber structures by a novel solution blow spinning device

    Directory of Open Access Journals (Sweden)

    Feng Liang

    2017-02-01

    Full Text Available The fabrication of three-dimensional scaffolds has attracted more attention in tissue engineering. The purpose of this study is to explore a new method for the fabrication of three-dimensional micro-nanofiber structures by combining solution blow spinning and rotating collector. In this study, we successfully fabricated fibers with a minimum diameter of 200 nm and a three-dimensional structure with a maximum porosity of 89.9%. At the same time, the influence of various parameters such as the solvent volatility, the shape of the collector, the feed rate of the solution and the applied gas pressure were studied. It is found that solvent volatility has large effect on the formation of the three-dimensional shape of the structure. The shape of the collector affects the porosity and fiber distribution of the three-dimensional structure. The fiber diameter and fiber uniformity can be controlled by adjusting the solution feed rate and the applied gas pressure. It is feasible to fabricate high-quality three-dimensional micro-nanofiber structure by this new method, which has great potential in tissue engineering.

  9. Mitral Valve Disease

    Science.gov (United States)

    ... for mitral valve replacement—mechanical valves (metal) or biological valves (tissue). The principal advantage of mechanical valves ... small risk of stroke due to blood clotting. Biological valves usually are made from animal tissue. Biological ...

  10. Sliding pressure control valve for pneumatic hammer drill

    Science.gov (United States)

    Polsky, Yarom [Albuquerque, NM

    2011-08-30

    A pneumatic device control apparatus and method comprising a ported valve slidably fitted over a feed tube of the pneumatic device, and using a compliant biasing device to constrain motion of the valve to provide asymmetric timing for extended pressurization of a power chamber and reduced pressurization of a return chamber of the pneumatic device. The pneumatic device can be a pneumatic hammer drill.

  11. Spin-Caloritronic Batteries

    DEFF Research Database (Denmark)

    Yu, Xiao-Qin; Zhu, Zhen-Gang; Su, Gang

    2017-01-01

    The thermoelectric performance of a topological energy converter is analyzed. The H-shaped device is based on a combination of transverse topological effects involving the spin: the inverse spin Hall effect and the spin Nernst effect. The device can convert a temperature drop in one arm into an e...

  12. Fluid mechanics of heart valves.

    Science.gov (United States)

    Yoganathan, Ajit P; He, Zhaoming; Casey Jones, S

    2004-01-01

    Valvular heart disease is a life-threatening disease that afflicts millions of people worldwide and leads to approximately 250,000 valve repairs and/or replacements each year. Malfunction of a native valve impairs its efficient fluid mechanic/hemodynamic performance. Artificial heart valves have been used since 1960 to replace diseased native valves and have saved millions of lives. Unfortunately, despite four decades of use, these devices are less than ideal and lead to many complications. Many of these complications/problems are directly related to the fluid mechanics associated with the various mechanical and bioprosthetic valve designs. This review focuses on the state-of-the-art experimental and computational fluid mechanics of native and prosthetic heart valves in current clinical use. The fluid dynamic performance characteristics of caged-ball, tilting-disc, bileaflet mechanical valves and porcine and pericardial stented and nonstented bioprostheic valves are reviewed. Other issues related to heart valve performance, such as biomaterials, solid mechanics, tissue mechanics, and durability, are not addressed in this review.

  13. Period-doubling bifurcation cascade observed in a ferromagnetic nanoparticle under the action of a spin-polarized current

    Energy Technology Data Exchange (ETDEWEB)

    Horley, Paul P., E-mail: paul.horley@cimav.edu.mx [Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Chihuahua/Monterrey, 120 Avenida Miguel de Cervantes, 31109 Chihuahua (Mexico); Kushnir, Mykola Ya. [Yuri Fedkovych Chernivtsi National University, 2 Kotsyubynsky str., 58012 Chernivtsi (Ukraine); Morales-Meza, Mishel [Centro de Investigación en Materiales Avanzados, S.C. (CIMAV), Chihuahua/Monterrey, 120 Avenida Miguel de Cervantes, 31109 Chihuahua (Mexico); Sukhov, Alexander [Institut für Physik, Martin-Luther Universität Halle-Wittenberg, 06120 Halle (Saale) (Germany); Rusyn, Volodymyr [Yuri Fedkovych Chernivtsi National University, 2 Kotsyubynsky str., 58012 Chernivtsi (Ukraine)

    2016-04-01

    We report on complex magnetization dynamics in a forced spin valve oscillator subjected to a varying magnetic field and a constant spin-polarized current. The transition from periodic to chaotic magnetic motion was illustrated with bifurcation diagrams and Hausdorff dimension – the methods developed for dissipative self-organizing systems. It was shown that bifurcation cascades can be obtained either by tuning the injected spin-polarized current or by changing the magnitude of applied magnetic field. The order–chaos transition in magnetization dynamics can be also directly observed from the hysteresis curves. The resulting complex oscillations are useful for development of spin-valve devices operating in harmonic and chaotic modes.

  14. Assisted circulation using the Tandemheart®, percutaneous transseptal left ventricular assist device, during percutaneous aortic valve implantation: The Rotterdam experience

    NARCIS (Netherlands)

    P. Vranckx (Pascal); A. Otten (Amber); C.J. Schultz (Carl); R.T. van Domburg (Ron); P.P.T. de Jaegere (Peter); P.W.J.C. Serruys (Patrick)

    2009-01-01

    textabstractAims: The morbidity and mortality of surgical aortic valve replacement are increased in elderly patients with multiple high risk comorbid conditions. Percutaneous prosthetic aortic valve replacement (PAVR) via the femoral arterial approach is feasible in selected patients, who are poor

  15. Proximal thoracic aorta dimensions after continuous-flow left ventricular assist device implantation: Longitudinal changes and relation to aortic valve insufficiency.

    Science.gov (United States)

    Fine, Nowell M; Park, Soon J; Stulak, John M; Topilsky, Yan; Daly, Richard C; Joyce, Lyle D; Pereira, Naveen L; Schirger, John A; Edwards, Brooks S; Lin, Grace; Kushwaha, Sudhir S

    2016-04-01

    In this study we examined the impact of continuous-flow left ventricular assist device (CF-LVAD) support on proximal thoracic aorta dimensions. Aortic root and ascending aorta diameter were measured from serial echocardiograms before and after CF-LVAD implantation in patients with ≥6 months of support, and correlated with the development of >mild aortic valve insufficiency (AI). Of 162 patients included, mean age was 58 ± 11 years and 128 (79%) were male. Seventy-nine (63%) were destination therapy patients. Mean aortic root and ascending aorta diameters at baseline, 1 month, 6 months, 12 months and long-term follow-up (mean 2.0 ± 1.4 years) were 3.5 ± 0.4, 3.5 ± 0.3, 3.9 ± 0.3, 3.9 ± 0.2 and 4.0 ± 0.3, and 3.3 ± 0.2, 3.3 ± 0.3, 3.6 ± 0.2, 3.6 ± 0.3 and 3.6 ± 0.3 cm, respectively. Only change in aortic root diameter from 1-month to 6-month follow-up reached statistical significance (p = 0.03). Nine (6%) patients had accelerated proximal thoracic aorta expansion (>0.5 cm/year), occurring predominantly in the first 6 months after implantation. These patients were older and more likely to have hypertension and baseline proximal thoracic aorta dilation. Forty-five (28%) patients developed >mild AI at long-term follow-up, including 7 of 9 (78%) of those with accelerated proximal thoracic aorta expansion. All 7 had aortic valves that remained closed throughout the cardiac cycle, and this, along with duration of CF-LVAD support and increase in aortic root diameter, were significantly associated with developing >mild AI. CF-LVAD patients have small increases in proximal thoracic aorta dimensions that predominantly occur within the first 6 months after implantation and then stabilize. Increasing aortic root diameter was associated with AI development. Copyright © 2016 International Society for Heart and Lung Transplantation. Published by Elsevier Inc. All rights reserved.

  16. 3D Printed Multimaterial Microfluidic Valve.

    Directory of Open Access Journals (Sweden)

    Steven J Keating

    Full Text Available We present a novel 3D printed multimaterial microfluidic proportional valve. The microfluidic valve is a fundamental primitive that enables the development of programmable, automated devices for controlling fluids in a precise manner. We discuss valve characterization results, as well as exploratory design variations in channel width, membrane thickness, and membrane stiffness. Compared to previous single material 3D printed valves that are stiff, these printed valves constrain fluidic deformation spatially, through combinations of stiff and flexible materials, to enable intricate geometries in an actuated, functionally graded device. Research presented marks a shift towards 3D printing multi-property programmable fluidic devices in a single step, in which integrated multimaterial valves can be used to control complex fluidic reactions for a variety of applications, including DNA assembly and analysis, continuous sampling and sensing, and soft robotics.

  17. Evaluating Graphene as a Channel Material in Spintronic Logic Devices

    Science.gov (United States)

    Anugrah, Yoska

    Spintronics, a class of devices that exploit the spin properties of electrons in addition to the charge properties, promises the possibility for nonvolatile logic and memory devices that operate at low power. Graphene is a material in which the spin orientation of electrons can be conserved over a long distance, which makes it an attractive channel material in spintronics devices. In this dissertation, the properties of graphene that are interesting for spintronics applications are explored. A robust fabrication process is described for graphene spin valves using Al2O3 tunnel tunnel barriers and Co ferromagnetic contacts. Spin transport was characterized in both few-layer exfoliated and single-layer graphene, and spin diffusion lengths and spin relaxation times were extracted using the nonlocal spin valve geometry and Hanle measurements. The effect of input-output asymmetry on the spin transport was investigated. The effect of an applied drift electric field on spin transport was investigated and the spin diffusion length was found to be tunable by a factor of 8X (suppressed to 1.6 microm and enhanced to 13 microm from the intrinsic length of 4.6 microm using electric field of +/-1800 V/cm). A mechanism to induce asymmetry without excess power dissipation is also described which utilizes a double buried-gate structure to tune the Fermi levels on the input and output sides of a graphene spin logic device independently. It was found that different spin scattering mechanisms were at play in the two halves of a small graphene strip. This suggests that the spin properties of graphene are strongly affected by its local environment, e.g. impurities, surface topography, defects. Finally, two-dimensional materials beyond graphene have been explored as spin channels. One such material is phosphorene, which has low spin-orbit coupling and high mobility, and the interface properties of ferromagnets (cobalt and permalloy) with this material were explored. This work could

  18. Improved electron injection in spin coated Alq3 incorporated ZnO thin film in the device for solution processed OLEDs

    Science.gov (United States)

    Dasi, Gnyaneshwar; Ramarajan, R.; Thangaraju, Kuppusamy

    2018-04-01

    We deposit tris-(8-hydroxyquinoline)aluminum (Alq3) incorporated zinc oxide (ZnO) thin films by spin coating method under the normal ambient. It showed the higher transmittance (90% at 550 nm) when compared to that (80% at 550 nm) of spin coated pure ZnO film. SEM studies show that the Alq3 incorporation in ZnO film also enhances the formation of small sized particles arranged in the network of wrinkles on the surface. XRD reveals the improved crystalline properties upon Alq3 inclusion. We fabricate the electron-only devices (EODs) with the structure of ITO/spin coated ZnO:Alq3 as ETL/Alq3 interlayer/LiF/Al. The device showed the higher electron current density of 2.75 mA/cm2 at 12V when compared to that (0.82 mA/cm2 at 12V) of the device using pure ZnO ETL. The device results show that it will be useful to fabricate the low-cost solution processed OLEDs for future lighting and display applications.

  19. Multifunctional four-port directional control valve constructed from logic valves

    International Nuclear Information System (INIS)

    Lisowski, E.; Czyżycki, W.; Rajda, J.

    2014-01-01

    Highlights: • Directional valve with standard ISO 440-08 has been constructed from logic valves. • Only one innovative valve may replace whole family of the standard valves. • CFD analysis and bench tests of the innovative valve has been carried. • Parameters of the innovative valve are equaling or surpassing the standard ones. • The innovative valve has additional possibilities of pressure and flow control. - Abstract: The paper refers to four-port solenoid pilot operated valves, which are subplate mounted in a hydraulic system in accordance with the ISO 4401 standard. Their widespread use in many machines and devices causes a continuing interest in the development of their design by both the scientific centers and the industry. This paper presents an innovative directional control valve based on the use of logic valves and a methodology followed for the design of it by using Solid Edge CAD and ANSYS/Fluent CFD software. The valve design methodology takes into account the need to seek solutions that minimize flow resistance through the valve. For this purpose, the flow paths are prepared by means of CAD software and pressure-flow curves are determined as a result of CFD analysis. The obtained curves are compared with the curves available in the catalogs of spool type directional control valves. The new solution allows to replace the whole family of spool type four-port directional control valves by one valve built of logic valves. In addition, the innovative directional control valve provides leak-proof shutting the flow paths off and also it can control flow rate and even pressure of working liquid. A prototype of the valve designed by the presented method has been made and tested on the test bench. The results quoted in the paper confirm that the developed logic type directional control valve is able to meet all designed connection configurations, and the obtained pressure-flow curves show very good conformity with the results of CFD analysis

  20. Impact of Disorder on Spin Dependent Transport Phenomena

    KAUST Repository

    Saidaoui, Hamed

    2016-07-03

    The impact of the spin degree of freedom on the transport properties of electrons traveling through magnetic materials has been known since the pioneer work of Mott [1]. Since then it has been demonstrated that the spin angular momentum plays a key role in the scattering process of electrons in magnetic multilayers. This role has been emphasized by the discovery of the Giant Magnetoresistance in 1988 by Fert and Grunberg [2, 3]. Among the numerous applications and effects that emerged in mesoscopic devices two mechanisms have attracted our attention during the course of this thesis: the spin transfer torque and the spin Hall effects. The former consists in the transfer of the spin angular momentum from itinerant carriers to local magnetic moments [4]. This mechanism results in the current-driven magnetization switching and excitations, which has potential application in terms of magnetic data storage and non-volatile memories. The latter, spin Hall effect, is considered as well to be one of the most fascinating mechanisms in condensed matter physics due to its ability of generating non-equilibrium spin currents without the need for any magnetic materials. In fact the spin Hall effect relies only on the presence of the spin-orbit interaction in order to create an imbalance between the majority and minority spins. The objective of this thesis is to investigate the impact of disorder on spin dependent transport phenomena. To do so, we identified three classes of systems on which such disorder may have a dramatic influence: (i) antiferromagnetic materials, (ii) impurity-driven spin-orbit coupled systems and (iii) two dimensional semiconducting electron gases with Rashba spin-orbit coupling. Antiferromagnetic materials - We showed that in antiferromagnetic spin-valves, spin transfer torque is highly sensitive to disorder, which prevents its experimental observation. To solve this issue, we proposed to use either a tunnel barrier as a spacer or a local spin torque using

  1. Homoepitaxial graphene tunnel barriers for spin transport (Presentation Recording)

    Science.gov (United States)

    Friedman, Adam L.

    2015-09-01

    Tunnel barriers are key elements for both charge-and spin-based electronics, offering devices with reduced power consumption and new paradigms for information processing. Such devices require mating dissimilar materials, raising issues of heteroepitaxy, interface stability, and electronic states that severely complicate fabrication and compromise performance. Graphene is the perfect tunnel barrier. It is an insulator out-of-plane, possesses a defect-free, linear habit, and is impervious to interdiffusion. Nonetheless, true tunneling between two stacked graphene layers is not possible in environmental conditions (magnetic field, temperature, etc.) usable for electronics applications. However, two stacked graphene layers can be decoupled using chemical functionalization. Here, we demonstrate homoepitaxial tunnel barrier devices in which graphene serves as both the tunnel barrier and the high mobility transport channel. Beginning with multilayer graphene, we fluorinate or hydrogenate the top layer to decouple it from the bottom layer, so that it serves as a single monolayer tunnel barrier for both charge and spin injection into the lower graphene transport channel. We demonstrate successful tunneling by measuring non-linear IV curves, and a weakly temperature dependent zero bias resistance. We perform lateral transport of spin currents in non-local spin-valve structures and determine spin lifetimes with the non-local Hanle effect to be commensurate with previous studies (~200 ps). However, we also demonstrate the highest spin polarization efficiencies (~45%) yet measured in graphene-based spin devices [1]. [1] A.L. Friedman, et al., Homoepitaxial tunnel barriers with functionalized graphene-on-graphene for charge and spin transport, Nat. Comm. 5, 3161 (2014).

  2. Ultrafast spin exchange-coupling torque via photo-excited charge-transfer processes

    Science.gov (United States)

    Ma, X.; Fang, F.; Li, Q.; Zhu, J.; Yang, Y.; Wu, Y. Z.; Zhao, H. B.; Lüpke, G.

    2015-10-01

    Optical control of spin is of central importance in the research of ultrafast spintronic devices utilizing spin dynamics at short time scales. Recently developed optical approaches such as ultrafast demagnetization, spin-transfer and spin-orbit torques open new pathways to manipulate spin through its interaction with photon, orbit, charge or phonon. However, these processes are limited by either the long thermal recovery time or the low-temperature requirement. Here we experimentally demonstrate ultrafast coherent spin precession via optical charge-transfer processes in the exchange-coupled Fe/CoO system at room temperature. The efficiency of spin precession excitation is significantly higher and the recovery time of the exchange-coupling torque is much shorter than for the demagnetization procedure, which is desirable for fast switching. The exchange coupling is a key issue in spin valves and tunnelling junctions, and hence our findings will help promote the development of exchange-coupled device concepts for ultrafast coherent spin manipulation.

  3. ESPINTRÓNICA, LA ELECTRONICA DEL ESPÍN SPINTRONICS, SPIN ELECTRONICS

    KAUST Repository

    Monteblanco, Elmer; Ortiz Pauyac, Christian; Savero, Williams; RojasSanchez, J. Carlos; Schuhl, A.

    2017-01-01

    Current technology seeks to develop nanoscale devices capable of storing and processing information. These devices would be difficult to make in the area of electronics, which is based on the manipulation of electric charge. However, thanks to advances in experimental and theoretical physics in the field of condensed matter, these devices are already a reality, belonging to the field of what we now call spintronics, which bases its functionality on the control of the electron’s spin, a property that can only be conceived at the quantum level. In this article we review this new perspective, describing giant- and tunneling- magnetoresistance, the spin transfer torque, and their applications such as MRAM memories, nano-oscillators and lateral spin valves.

  4. ESPINTRÓNICA, LA ELECTRONICA DEL ESPÍN SPINTRONICS, SPIN ELECTRONICS

    KAUST Repository

    Monteblanco, Elmer

    2017-03-14

    Current technology seeks to develop nanoscale devices capable of storing and processing information. These devices would be difficult to make in the area of electronics, which is based on the manipulation of electric charge. However, thanks to advances in experimental and theoretical physics in the field of condensed matter, these devices are already a reality, belonging to the field of what we now call spintronics, which bases its functionality on the control of the electron’s spin, a property that can only be conceived at the quantum level. In this article we review this new perspective, describing giant- and tunneling- magnetoresistance, the spin transfer torque, and their applications such as MRAM memories, nano-oscillators and lateral spin valves.

  5. Piezoelectric valve

    Science.gov (United States)

    Petrenko, Serhiy Fedorovich

    2013-01-15

    A motorized valve has a housing having an inlet and an outlet to be connected to a pipeline, a saddle connected with the housing, a turn plug having a rod, the turn plug cooperating with the saddle, and a drive for turning the valve body and formed as a piezoelectric drive, the piezoelectric drive including a piezoelectric generator of radially directed standing acoustic waves, which is connected with the housing and is connectable with a pulse current source, and a rotor operatively connected with the piezoelectric generator and kinematically connected with the rod of the turn plug so as to turn the turn plug when the rotor is actuated by the piezoelectric generator.

  6. Proposal for a graphene-based all-spin logic gate

    International Nuclear Information System (INIS)

    Su, Li; Zhao, Weisheng; Zhang, Yue; Querlioz, Damien; Klein, Jacques-Olivier; Dollfus, Philippe; Bournel, Arnaud; Zhang, Youguang

    2015-01-01

    In this work, we present a graphene-based all-spin logic gate (G-ASLG) that integrates the functionalities of perpendicular anisotropy magnetic tunnel junctions (p-MTJs) with spin transport in graphene-channel. It provides an ideal integration of logic and memory. The input and output states are defined as the relative magnetization between free layer and fixed layer of p-MTJs. They can be probed by the tunnel magnetoresistance and controlled by spin transfer torque effect. Using lateral non-local spin valve, the spin information is transmitted by the spin-current interaction through graphene channels. By using a physics-based spin current compact model, the operation of G-ASLG is demonstrated and its performance is analyzed. It allows us to evaluate the influence of parameters, such as spin injection efficiency, spin diffusion length, contact area, the device length, and their interdependence, and to optimize the energy and dynamic performance. Compared to other beyond-CMOS solutions, longer spin information transport length (∼μm), higher data throughput, faster computing speed (∼ns), and lower power consumption (∼μA) can be expected from the G-ASLG

  7. Proposal for a graphene-based all-spin logic gate

    Science.gov (United States)

    Su, Li; Zhao, Weisheng; Zhang, Yue; Querlioz, Damien; Zhang, Youguang; Klein, Jacques-Olivier; Dollfus, Philippe; Bournel, Arnaud

    2015-02-01

    In this work, we present a graphene-based all-spin logic gate (G-ASLG) that integrates the functionalities of perpendicular anisotropy magnetic tunnel junctions (p-MTJs) with spin transport in graphene-channel. It provides an ideal integration of logic and memory. The input and output states are defined as the relative magnetization between free layer and fixed layer of p-MTJs. They can be probed by the tunnel magnetoresistance and controlled by spin transfer torque effect. Using lateral non-local spin valve, the spin information is transmitted by the spin-current interaction through graphene channels. By using a physics-based spin current compact model, the operation of G-ASLG is demonstrated and its performance is analyzed. It allows us to evaluate the influence of parameters, such as spin injection efficiency, spin diffusion length, contact area, the device length, and their interdependence, and to optimize the energy and dynamic performance. Compared to other beyond-CMOS solutions, longer spin information transport length (˜μm), higher data throughput, faster computing speed (˜ns), and lower power consumption (˜μA) can be expected from the G-ASLG.

  8. Spin pumping through a topological insulator probed by x-ray detected ferromagnetic resonance

    Science.gov (United States)

    Figueroa, A. I.; Baker, A. A.; Collins-McIntyre, L. J.; Hesjedal, T.; van der Laan, G.

    2016-02-01

    In the field of spintronics, the generation of a pure spin current (without macroscopic charge flow) through spin pumping of a ferromagnetic (FM) layer opens up the perspective of a new generation of dissipation-less devices. Microwave driven ferromagnetic resonance (FMR) can generate a pure spin current that enters adjacent layers, allowing for both magnetization reversal (through spin-transfer torque) and to probe spin coherence in non-magnetic materials. However, standard FMR is unable to probe multilayer dynamics directly, since the measurement averages over the contributions from the whole system. The synchrotron radiation-based technique of x-ray detected FMR (XFMR) offers an elegant solution to this drawback, giving access to element-, site-, and layer-specific dynamical measurements in heterostructures. In this work, we show how XFMR has provided unique information to understand spin pumping and spin transfer torque effects through a topological insulator (TI) layer in a pseudo-spin valve heterostructure. We demonstrate that TIs function as efficient spin sinks, while also allowing a limited dynamic coupling between ferromagnetic layers. These results shed new light on the spin dynamics of this novel class of materials, and suggest future directions for the development of room temperature TI-based spintronics.

  9. Antiferromagnetic spin-orbitronics

    KAUST Repository

    Manchon, Aurelien; Saidaoui, Hamed Ben Mohamed; Ghosh, Sumit

    2015-01-01

    Antiferromagnets have long remained an intriguing and exotic state of matter, whose application has been restricted to enabling interfacial exchange bias in metallic and tunneling spin-valves [1]. Their role in the expanding field of applied spintronics has been mostly passive and the in-depth investigation of their basic properties mostly considered from a fundamental perspective.

  10. Antiferromagnetic spin-orbitronics

    KAUST Repository

    Manchon, Aurelien

    2015-05-01

    Antiferromagnets have long remained an intriguing and exotic state of matter, whose application has been restricted to enabling interfacial exchange bias in metallic and tunneling spin-valves [1]. Their role in the expanding field of applied spintronics has been mostly passive and the in-depth investigation of their basic properties mostly considered from a fundamental perspective.

  11. Characteristic analysis of servo valve

    International Nuclear Information System (INIS)

    Ko, J. H.; Ryu, D. R.; Lee, J. H.; Kim, Y. S.; Na, J. C.; Kim, D. S.

    2008-01-01

    Electro-pneumatic servo valve is an electro-mechanical device which converts electric signals into a proper pneumatic flow rate or pressure. In order to improve the overall performance of pneumatic servo systems, electro-pneumatic servo valves are required, which have fast dynamic characteristics, no air leakage at a null point, and can be fabricated at a low-cost. The first objective of this research is to design and to fabricate a new electro-pneumatic servo valve which satisfies the above-mentioned requirements. In order to design the mechanism of the servo valve optimally, the flow inside the valve depending upon the position of spool was analyzed variously, and on the basis of such analysis results, the valve mechanism, which was formed by combination of the spool and the sleeve, was designed and manufactured. And a tester for conducting an overall performance test was designed and manufactured, and as a result of conducting the flow rate test, the pressure test and the frequency test on the developed pneumatic servo valve

  12. Injection and Scattering of Polarized Spins at Nanoscale Polymer Interfaces

    National Research Council Canada - National Science Library

    Epstein, Arthur J

    2004-01-01

    We made excellent progress several directions. We demonstrated that V[TCNE]̃2 is a room temperature fully spin polarized magnetic semiconductor of interest for spintronic applications, including spin valves...

  13. Heterostructures for Realizing Magnon-Induced Spin Transfer Torque

    Directory of Open Access Journals (Sweden)

    P. B. Jayathilaka

    2012-01-01

    Full Text Available This work reports efforts fabricating heterostructures of different materials relevant for the realization of magnon-induced spin transfer torques. We find the growth of high-quality magnetite on MgO substrates to be straightforward, while using transition metal buffer layers of Fe, Cr, Mo, and Nb can alter the structural and magnetic properties of the magnetite. Additionally, we successfully fabricated and characterized Py/Cr/Fe3O4 and Fe3O4/Cr/Fe3O4 spin valve structures. For both, we observe a relatively small giant magnetoresistance and confirm an inverse dependence on spacer layer thickness. Thus, we have shown certain materials combinations that may form the heterostructures that are the building blocks necessary to achieve magnon-induced spin transfer torque devices.

  14. Structural and magnetic properties of Ni{sub 78}Fe{sub 22} thin films sandwiched between low-softening-point glasses and application in spin devices

    Energy Technology Data Exchange (ETDEWEB)

    Misawa, Takahiro; Mori, Sumito [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Komine, Takashi [Faculty of Engineering, Ibaraki University, Hitachi, Ibaraki 316-8511 (Japan); Fujioka, Masaya; Nishii, Junji [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan); Kaiju, Hideo, E-mail: kaiju@es.hokudai.ac.jp [Research Institute for Electronic Science, Hokkaido University, Sapporo, Hokkaido 001-0020 (Japan)

    2016-12-30

    Graphical abstract: This paper presents the first demonstration of the formation of Ni{sub 78}Fe{sub 22} thin films sandwiched between low-softening-point (LSP) glasses used in spin quantum cross (SQC) devices and the theoretical prediction of spin filter effect in Ni{sub 78}Fe{sub 22}-based SQC devices. The fomation of the LSP-glass/Ni{sub 78}Fe{sub 22}/LSP-glass structures was successfully demonstrated using a newly proposed thermal pressing technique. Interestingly, this technique gives rise to both a highly-oriented crystal growth in Ni{sub 78}Fe{sub 22} thin films and a 100-fold enhancement in coercivity, in contrast to those of as-deposited Ni{sub 78}Fe{sub 22} thin films. This remarkable increase in coercivity can be explained by the calculation based on two-dimensional random anisotropy model. These excellent features on structural and magnetic properties allowed us to achieve that the stray magnetic field was uniformly generated from the Ni{sub 78}Fe{sub 22} thin-film edge in the direction perpendicular to the cross section of the LSP-glass/Ni{sub 78}Fe{sub 22}/LSP-glass structures. As we calculated the stray magnetic field generated between the two edges of Ni{sub 78}Fe{sub 22} thin-film electrodes in SQC devices, a high stray field of approximately 5 kOe was generated when the gap distance between two edges of the Ni{sub 78}Fe{sub 22} thin-film electrodes was less than 5 nm and the thickness of Ni{sub 78}Fe{sub 22} was greater than 20 nm. These experimental and calculated results suggest that Ni{sub 78}Fe{sub 22} thin films sandwiched between LSP glasses can be used as electrodes in SQC devices, providing a spin-filter effect, and also our proposed techniques utilizing magnetic thin-film edges will open up new opportunities for the creation of high performance spin devices, such as large magnetoresistance devices and nanoscale spin injectors. Our paper is of strong interest to the broad audience of Applied Surface Science, as it demonstrates that the

  15. Neutron spin quantum precession using multilayer spin splitters and a phase-spin echo interferometer

    International Nuclear Information System (INIS)

    Ebisawa, Toru; Tasaki, Seiji; Kawai, Takeshi; Hino, Masahiro; Akiyoshi, Tsunekazu; Achiwa, Norio; Otake, Yoshie; Funahashi, Haruhiko.

    1996-01-01

    Neutron spin quantum precession by multilayer spin splitter has been demonstrated using a new spin interferometer. The multilayer spin splitter consists of a magnetic multilayer mirror on top, followed by a gap layer and a non magnetic multilayer mirror which are evaporated on a silicon substrate. Using the multilayer spin splitter, a polarized neutron wave in a magnetic field perpendicular to the polarization is split into two spin eigenstates with a phase shift in the direction of the magnetic field. The spin quantum precession is equal to the phase shift, which depends on the effective thickness of the gap layer. The demonstration experiments verify the multilayer spin splitter as a neutron spin precession device as well as the coherent superposition principle of the two spin eigenstates. We have developed a new phase-spin echo interferometer using the multilayer spin splitters. We present successful performance tests of the multilayer spin splitter and the phase-spin echo interferometer. (author)

  16. The future of transcatheter mitral valve interventions

    DEFF Research Database (Denmark)

    Maisano, Francesco; Alfieri, Ottavio; Banai, Shmuel

    2015-01-01

    of transcatheter mitral valve interventions will be. The purpose of the present report is to review the current state-of-the-art of mitral valve intervention, and to identify the potential future scenarios, which might benefit most from the transcatheter repair and replacement devices under development....

  17. Surgical removal of atrial septal defect occlusion device and mitral valve replacement in a 39-year-old female patient with infective endocarditis

    Directory of Open Access Journals (Sweden)

    A S Zotov

    2018-02-01

    Full Text Available Atrial septal defects represent the second most frequent congenital heart disease after ventricular septal defects. Transcatheter closure of an atrial septal defect is usually performed following strict indications on patients with significant left-to-right shunt. Infective endocarditis after transcatheter implantation of atrial septal defect occluder is an extremely rare complication. We report a case of infective endocarditis of the mitral valve (with severe mitral valve insufficiency in a 39-year-old female patient 13 years after transcatheter closure of an atrial septal defect. Complex prophylactic antibiotic coverage was performed prior to surgical intervention. Surgical removal of atrial septal defect occluder, mitral valve replacement, atrial septal defect closure and left atrial appendage resection were performed. Postoperative course was uneventful.

  18. Proposal for a dual-gate spin field effect transistor: A device with very small switching voltage and a large ON to OFF conductance ratio

    Science.gov (United States)

    Wan, J.; Cahay, M.; Bandyopadhyay, S.

    2008-06-01

    We propose a new dual gate spin field effect transistor (SpinFET) consisting of a quasi one-dimensional semiconductor channel sandwiched between two half-metallic contacts. The gate voltage aligns and de-aligns the incident electron energy with Ramsauer resonance levels in the channel, thereby modulating the source-to-drain conductance. The device can be switched from ON to OFF with a few mV change in the gate voltage, resulting in exceedingly low dynamic power dissipation during switching. The conductance ON/OFF ratio stays fairly large ( ∼60) up to a temperature of 10 K. This conductance ratio is comparable to that achievable with carbon nanotube transistors.

  19. A controllable spin prism

    International Nuclear Information System (INIS)

    Hakioglu, T

    2009-01-01

    Based on Khodas et al (2004 Phys. Rev. Lett. 92 086602), we propose a device acting like a controllable prism for an incident spin. The device is a large quantum well where Rashba and Dresselhaus spin-orbit interactions are present and controlled by the plunger gate potential, the electric field and the barrier height. A totally destructive interference can be manipulated externally between the Rashba and Dresselhaus couplings. The spin-dependent transmission/reflection amplitudes are calculated as the control parameters are changed. The device operates as a spin prism/converter/filter in different regimes and may stimulate research in promising directions in spintronics in analogy with linear optics.

  20. Electron spin and nuclear spin manipulation in semiconductor nanosystems

    International Nuclear Information System (INIS)

    Hirayama, Yoshiro; Yusa, Go; Sasaki, Satoshi

    2006-01-01

    Manipulations of electron spin and nuclear spin have been studied in AlGaAs/GaAs semiconductor nanosystems. Non-local manipulation of electron spins has been realized by using the correlation effect between localized and mobile electron spins in a quantum dot- quantum wire coupled system. Interaction between electron and nuclear spins was exploited to achieve a coherent control of nuclear spins in a semiconductor point contact device. Using this device, we have demonstrated a fully coherent manipulation of any two states among the four spin levels of Ga and As nuclei. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Efficient Spin Injection into Semiconductor

    International Nuclear Information System (INIS)

    Nahid, M.A.I.

    2010-06-01

    Spintronic research has made tremendous progress nowadays for making future devices obtain extra advantages of low power, and faster and higher scalability compared to present electronic devices. A spintronic device is based on the transport of an electron's spin instead of charge. Efficient spin injection is one of the very important requirements for future spintronic devices. However, the effective spin injection is an exceedingly difficult task. In this paper, the importance of spin injection, basics of spin current and the essential requirements of spin injection are illustrated. The experimental technique of electrical spin injection into semiconductor is also discussed based on the experimental experience. The electrical spin injection can easily be implemented for spin injection into any semiconductor. (author)

  2. Spin pumping through a topological insulator probed by x-ray detected ferromagnetic resonance

    Energy Technology Data Exchange (ETDEWEB)

    Figueroa, A.I., E-mail: aifigueg@gmail.com [Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom); Baker, A.A. [Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom); Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Collins-McIntyre, L.J.; Hesjedal, T. [Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU (United Kingdom); Laan, G. van der [Magnetic Spectroscopy Group, Diamond Light Source, Didcot OX11 0DE (United Kingdom)

    2016-02-15

    In the field of spintronics, the generation of a pure spin current (without macroscopic charge flow) through spin pumping of a ferromagnetic (FM) layer opens up the perspective of a new generation of dissipation-less devices. Microwave driven ferromagnetic resonance (FMR) can generate a pure spin current that enters adjacent layers, allowing for both magnetization reversal (through spin-transfer torque) and to probe spin coherence in non-magnetic materials. However, standard FMR is unable to probe multilayer dynamics directly, since the measurement averages over the contributions from the whole system. The synchrotron radiation-based technique of x-ray detected FMR (XFMR) offers an elegant solution to this drawback, giving access to element-, site-, and layer-specific dynamical measurements in heterostructures. In this work, we show how XFMR has provided unique information to understand spin pumping and spin transfer torque effects through a topological insulator (TI) layer in a pseudo-spin valve heterostructure. We demonstrate that TIs function as efficient spin sinks, while also allowing a limited dynamic coupling between ferromagnetic layers. These results shed new light on the spin dynamics of this novel class of materials, and suggest future directions for the development of room temperature TI-based spintronics. - Highlights: • X-ray detected ferromagnetic resonance is used to study the spin pumping phenomenon. • We show a powerful way to get information of spin transfer between magnetic layers. • We observe spin pumping through a topological insulators at room temperature. • Topological insulators function as efficient spin sinks.

  3. Spin pumping through a topological insulator probed by x-ray detected ferromagnetic resonance

    International Nuclear Information System (INIS)

    Figueroa, A.I.; Baker, A.A.; Collins-McIntyre, L.J.; Hesjedal, T.; Laan, G. van der

    2016-01-01

    In the field of spintronics, the generation of a pure spin current (without macroscopic charge flow) through spin pumping of a ferromagnetic (FM) layer opens up the perspective of a new generation of dissipation-less devices. Microwave driven ferromagnetic resonance (FMR) can generate a pure spin current that enters adjacent layers, allowing for both magnetization reversal (through spin-transfer torque) and to probe spin coherence in non-magnetic materials. However, standard FMR is unable to probe multilayer dynamics directly, since the measurement averages over the contributions from the whole system. The synchrotron radiation-based technique of x-ray detected FMR (XFMR) offers an elegant solution to this drawback, giving access to element-, site-, and layer-specific dynamical measurements in heterostructures. In this work, we show how XFMR has provided unique information to understand spin pumping and spin transfer torque effects through a topological insulator (TI) layer in a pseudo-spin valve heterostructure. We demonstrate that TIs function as efficient spin sinks, while also allowing a limited dynamic coupling between ferromagnetic layers. These results shed new light on the spin dynamics of this novel class of materials, and suggest future directions for the development of room temperature TI-based spintronics. - Highlights: • X-ray detected ferromagnetic resonance is used to study the spin pumping phenomenon. • We show a powerful way to get information of spin transfer between magnetic layers. • We observe spin pumping through a topological insulators at room temperature. • Topological insulators function as efficient spin sinks.

  4. Safety valve opening and closing operation monitor

    International Nuclear Information System (INIS)

    Kodama, Kunio; Takeshima, Ikuo; Takahashi, Kiyokazu.

    1981-01-01

    Purpose: To enable the detection of the closing of a safety valve when the internal pressure in a BWR type reactor is a value which will close the safety valve, by inputting signals from a pressure detecting device mounted directly at a reactor vessel and a safety valve discharge pressure detecting device to an AND logic circuit. Constitution: A safety valve monitor is formed of a pressure switch mounted at a reactor pressure vessel, a pressure switch mounted at the exhaust pipe of the escape safety valve and a logic circuit and the lide. When the input pressure of the safety valve is raised so that the valve and the pressure switch mounted at the exhaust pipe are operated, an alarm is indicated, and the operation of the pressure switch mounted at a pressure vessel is eliminated. If the safety valve is not reclosed when the vessel pressure is decreased lower than the pressure at which it is to be reclosed after the safety valve is operated, an alarm is generated by the logic circuit since both the pressure switches are operated. (Sekiya, K.)

  5. Spin-transport-phenomena in metals, semiconductors, and insulators

    Energy Technology Data Exchange (ETDEWEB)

    Althammer, Matthias Klaus

    2012-07-19

    Assuming that one could deterministically inject, transport, manipulate, store and detect spin information in solid state devices, the well-established concepts of charge-based electronics could be transferred to the spin realm. This thesis explores the injection, transport, manipulation and storage of spin information in metallic conductors, semiconductors, as well as electrical insulators. On the one hand, we explore the spin-dependent properties of semiconducting zinc oxide thin films deposited via laser-molecular beam epitaxy (laser-MBE). After demonstrating that the zinc oxide films fabricated during this thesis have excellent structural, electrical, and optical properties, we investigate the spin-related properties by optical pump/probe, electrical injection/optical detection, and all electrical spin valve-based experiments. The two key results from these experiments are: (i) Long-lived spin states with spin dephasing times of 10 ns at 10 K related to donor bound excitons can be optically addressed. (ii) The spin dephasing times relevant for electrical transport-based experiments are {<=} 2 ns at 10 K and are correlated with structural quality. On the other hand we focus on two topics of current scientific interest: the comparison of the magnetoresistance to the magnetothermopower of conducting ferromagnets, and the investigation of pure spin currents generated in ferromagnetic insulator/normal metal hybrid structures. We investigate the magnetoresistance and magnetothermopower of gallium manganese arsenide and Heusler thin films as a function of external magnetic field orientation. Using a series expansion of the resistivity and Seebeck tensors and the inherent symmetry of the sample's crystal structure, we show that a full quantitative extraction of the transport tensors from such experiments is possible. Regarding the spin currents in ferromagnetic insulator/normal metal hybrid structures we studied the spin mixing conductance in yttrium iron garnet

  6. Non-local electrical spin injection and detection in germanium at room temperature

    Science.gov (United States)

    Rortais, F.; Vergnaud, C.; Marty, A.; Vila, L.; Attané, J.-P.; Widiez, J.; Zucchetti, C.; Bottegoni, F.; Jaffrès, H.; George, J.-M.; Jamet, M.

    2017-10-01

    Non-local carrier injection/detection schemes lie at the very foundation of information manipulation in integrated systems. This paradigm consists in controlling with an external signal the channel where charge carriers flow between a "source" and a well separated "drain." The next generation electronics may operate on the spin of carriers in addition to their charge and germanium appears as the best hosting material to develop such a platform for its compatibility with mainstream silicon technology and the predicted long electron spin lifetime at room temperature. In this letter, we demonstrate injection of pure spin currents (i.e., with no associated transport of electric charges) in germanium, combined with non-local spin detection at 10 K and room temperature. For this purpose, we used a lateral spin valve with epitaxially grown magnetic tunnel junctions as spin injector and spin detector. The non-local magnetoresistance signal is clearly visible and reaches ≈15 mΩ at room temperature. The electron spin lifetime and diffusion length are 500 ps and 1 μm, respectively, the spin injection efficiency being as high as 27%. This result paves the way for the realization of full germanium spintronic devices at room temperature.

  7. Aortic valve bypass

    DEFF Research Database (Denmark)

    Lund, Jens T; Jensen, Maiken Brit; Arendrup, Henrik

    2013-01-01

    In aortic valve bypass (AVB) a valve-containing conduit is connecting the apex of the left ventricle to the descending aorta. Candidates are patients with symptomatic aortic valve stenosis rejected for conventional aortic valve replacement (AVR) or transcatheter aortic valve implantation (TAVI). ...

  8. Optothermally actuated capillary burst valve

    DEFF Research Database (Denmark)

    Eriksen, Johan; Bilenberg, Brian; Kristensen, Anders

    2017-01-01

    be burst by raising the temperature due to the temperature dependence of the fluid surface tension. We address individual valves by using a local heating platform based on a thin film of near infrared absorber dye embedded in the lid used to seal the microfluidic device [L. H. Thamdrup et al., Nano Lett...

  9. Efficient spin-filtering, magnetoresistance and negative differential resistance effects of a one-dimensional single-molecule magnet Mn(dmit2-based device with graphene nanoribbon electrodes

    Directory of Open Access Journals (Sweden)

    N. Liu

    2017-12-01

    Full Text Available We present first-principle spin-dependent quantum transport calculations in a molecular device constructed by one single-molecule magnet Mn(dmit2 and two graphene nanoribbon electrodes. Our results show that the device could generate perfect spin-filtering performance in a certain bias range both in the parallel configuration (PC and the antiparallel configuration (APC. At the same time, a magnetoresistance effect, up to a high value of 103%, can be realized. Moreover, visible negative differential resistance phenomenon is obtained for the spin-up current of the PC. These results suggest that our one-dimensional molecular device is a promising candidate for multi-functional spintronics devices.

  10. Transcatheter aortic valve replacement

    Science.gov (United States)

    ... gov/ency/article/007684.htm Transcatheter aortic valve replacement To use the sharing features on this page, please enable JavaScript. Transcatheter aortic valve replacement (TAVR) is surgery to replace the aortic valve. ...

  11. On the fractography of overload, stress corrosion, and cyclic fatigue failures in pyrolytic-carbon materials used in prosthetic heart-valve devices.

    Science.gov (United States)

    Ritchie, R O; Dauskardt, R H; Pennisi, F J

    1992-01-01

    A scanning electron microscopy study is reported of the nature and morphology of fracture surfaces in pyrocarbons commonly used for the manufacture of mechanical heart-valve prostheses. Specifically, silicon-alloyed low-temperature-isotropic (LTI)-pyrolytic carbon is examined, both as a coating on graphite and as a monolithic material, following overload, stress corrosion (static fatigue), and cyclic fatigue failures in a simulated physiological environment of 37 degrees C Ringer's solution. It is found that, in contrast to most metallic materials yet in keeping with many ceramics, there are no distinct fracture morphologies in pyro-carbons which are characteristic of a specific mode of loading; fracture surfaces appear to be identical for both catastrophic and subcritical crack growth under either sustained or cyclic loading. We conclude that caution should be used in assigning the likely cause of failure of pyrolytic carbon heart-valve components using fractographic examination.

  12. Device for controlling the current by an electromagnetic load, particularly by an electromagnetic injection valve of an internal combustion engine. Einrichtung zum Steuern des Stromes durch einen elektromagnetischen Verbraucher, insbesondere durch ein elektromagnetisch betaetigbares Einspritzventil einer Brennkraftmaschine

    Energy Technology Data Exchange (ETDEWEB)

    Dilger, P; Hoenig, G; Kauff, H

    1980-07-24

    The invention refers to a device for controlling the current by an electromagnetic load, particularly the electromagnetically actuated injection valve of an internal combustion engine. A first electrical switching device and an ammeter are connected in series with the electromagnetic load between two voltage supply wires, with a free running circuit and a threshold switch together with the ammeter. The invention is characterised by the fact that the free running circuit has a series circuit consisting of a second electrical switching device and a second ammeter, and the first switching device is controlled, depending on time and depending on reaching the upper and lower limits of current flowing through the load and reaching the lower threshold value. The ammeter in the free running circuit has at least one threshold value switch, whose output is coupled to a time control circuit for one of the two switching devices. The time dependent flow control is carried out during the stopping phase of the electro-magnetic load by counting processes.

  13. Magnetically operated check valve

    Science.gov (United States)

    Morris, Brian G.; Bozeman, Richard J., Jr.

    1994-06-01

    A magnetically operated check valve is disclosed. The valve is comprised of a valve body and a movable poppet disposed therein. A magnet attracts the poppet to hold the valve shut until the force of fluid flow through the valve overcomes the magnetic attraction and moves the poppet to an unseated, open position. The poppet and magnet are configured and disposed to trap a magnetically attracted particulate and prevent it from flowing to a valve seating region.

  14. What Is Heart Valve Surgery?

    Science.gov (United States)

    ... working correctly. Most valve replacements involve the aortic Tricuspid valve and mitral valves. The aortic valve separates ... where it shouldn’t. This is called incompetence, insufficiency or regurgitation. • Prolapse — mitral valve flaps don’t ...

  15. What Is Heart Valve Disease?

    Science.gov (United States)

    ... and replacing it with a man-made or biological valve. Biological valves are made from pig, cow, or human ... the valve. Man-made valves last longer than biological valves and usually don’t have to be ...

  16. Electron-Spin Filters Would Offer Spin Polarization Greater than 1

    Science.gov (United States)

    Ting, David Z.

    2009-01-01

    A proposal has been made to develop devices that would generate spin-polarized electron currents characterized by polarization ratios having magnitudes in excess of 1. Heretofore, such devices (denoted, variously, as spin injectors, spin polarizers, and spin filters) have typically offered polarization ratios having magnitudes in the approximate range of 0.01 to 0.1. The proposed devices could be useful as efficient sources of spin-polarized electron currents for research on spintronics and development of practical spintronic devices.

  17. The influence of interlayer exchange coupling in giant-magnetoresistive devices on spin diode effect in wide frequency range

    Energy Technology Data Exchange (ETDEWEB)

    Ziętek, Sławomir, E-mail: zietek@agh.edu.pl; Skowroński, Witold; Wiśniowski, Piotr; Czapkiewicz, Maciej; Stobiecki, Tomasz [Department of Electronics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland); Ogrodnik, Piotr [Department of Electronics, AGH University of Science and Technology, Al. Mickiewicza 30, 30-059 Kraków (Poland); Faculty of Physics, Warsaw University of Technology, ul. Koszykowa 75, 00-662 Warszawa (Poland); Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań (Poland); Barnaś, Józef [Institute of Molecular Physics, Polish Academy of Sciences, ul. Smoluchowskiego 17, 60-179 Poznań (Poland); Faculty of Physics, Adam Mickiewicz University, ul. Umultowska 85, 61-614 Poznań (Poland)

    2015-09-21

    Spin diode effect in a giant magnetoresistive strip is measured in a broad frequency range, including resonance and off-resonance frequencies. The off-resonance dc signal is relatively strong and also significantly dependent on the exchange coupling between magnetic films through the spacer layer. The measured dc signal is described theoretically by taking into account magnetic dynamics induced by Oersted field created by an ac current flowing through the system.

  18. Ultrathin Epitaxial Ferromagneticγ-Fe2O3Layer as High Efficiency Spin Filtering Materials for Spintronics Device Based on Semiconductors

    KAUST Repository

    Li, Peng; Xia, Chuan; Zhu, Zhiyong; Wen, Yan; Zhang, Qiang; Alshareef, Husam N.; Zhang, Xixiang

    2016-01-01

    In spintronics, identifying an effective technique for generating spin-polarized current has fundamental importance. The spin-filtering effect across a ferromagnetic insulating layer originates from unequal tunneling barrier heights for spin

  19. Spin-torque oscillation in large size nano-magnet with perpendicular magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Luo, Linqiang, E-mail: LL6UK@virginia.edu [Department of Physics, University of Virginia, Charlottesville, VA 22904 (United States); Kabir, Mehdi [Department of Electrical & Computer Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Dao, Nam; Kittiwatanakul, Salinporn [Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Cyberey, Michael [Department of Electrical Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Wolf, Stuart A. [Department of Physics, University of Virginia, Charlottesville, VA 22904 (United States); Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Institute of Defense Analyses, Alexandria, VA 22311 (United States); Stan, Mircea [Department of Electrical & Computer Engineering, University of Virginia, Charlottesville, VA 22904 (United States); Lu, Jiwei [Department of Materials Science & Engineering, University of Virginia, Charlottesville, VA 22904 (United States)

    2017-06-15

    Highlights: • 500 nm size nano-pillar device was fabricated by photolithography techniques. • A magnetic hybrid structure was achieved with perpendicular magnetic fields. • Spin torque switching and oscillation was demonstrated in the large sized device. • Micromagnetic simulations accurately reproduced the experimental results. • Simulations demonstrated the synchronization of magnetic inhomogeneities. - Abstract: DC current induced magnetization reversal and magnetization oscillation was observed in 500 nm large size Co{sub 90}Fe{sub 10}/Cu/Ni{sub 80}Fe{sub 20} pillars. A perpendicular external field enhanced the coercive field separation between the reference layer (Co{sub 90}Fe{sub 10}) and free layer (Ni{sub 80}Fe{sub 20}) in the pseudo spin valve, allowing a large window of external magnetic field for exploring the free-layer reversal. A magnetic hybrid structure was achieved for the study of spin torque oscillation by applying a perpendicular field >3 kOe. The magnetization precession was manifested in terms of the multiple peaks on the differential resistance curves. Depending on the bias current and applied field, the regions of magnetic switching and magnetization precession on a dynamical stability diagram has been discussed in details. Micromagnetic simulations are shown to be in good agreement with experimental results and provide insight for synchronization of inhomogeneities in large sized device. The ability to manipulate spin-dynamics on large size devices could be proved useful for increasing the output power of the spin-transfer nano-oscillators (STNOs).

  20. Spin Orbit Torque in Ferromagnetic Semiconductors

    KAUST Repository

    Li, Hang

    2016-01-01

    Electrons not only have charges but also have spin. By utilizing the electron spin, the energy consumption of electronic devices can be reduced, their size can be scaled down and the efficiency of `read' and `write' in memory devices can

  1. Influence of face-centered-cubic texturing of Co2Fe6B2 pinned layer on tunneling magnetoresistance ratio decrease in Co2Fe6B2/MgO-based p-MTJ spin valves stacked with a [Co/Pd](n)-SyAF layer.

    Science.gov (United States)

    Takemura, Yasutaka; Lee, Du-Yeong; Lee, Seung-Eun; Chae, Kyo-Suk; Shim, Tae-Hun; Lian, Guoda; Kim, Moon; Park, Jea-Gun

    2015-05-15

    The TMR ratio of Co2Fe6B2/MgO-based p-MTJ spin valves stacked with a [Co/Pd]n-SyAF layer decreased rapidly when the ex situ magnetic annealing temperature (Tex) was increased from 275 to 325 °C, and this decrease was associated with degradation of the Co2Fe6B2 pinned layer rather than the Co2Fe6B2 free layer. At a Tex above 325 °C the amorphous Co2Fe6B2 pinned layer was transformed into a face-centered-cubic (fcc) crystalline layer textured from [Co/Pd]n-SyAF, abruptly reducing the Δ1 coherence tunneling of perpendicular-spin-torque electrons between the (100) MgO tunneling barrier and the fcc Co2Fe6B2 pinned layer.

  2. High-pressure, high-temperature magic angle spinning nuclear magnetic resonance devices and processes for making and using same

    Science.gov (United States)

    Hu, Jian Zhi; Hu, Mary Y.; Townsend, Mark R.; Lercher, Johannes A.; Peden, Charles H. F.

    2015-10-06

    Re-usable ceramic magic angle spinning (MAS) NMR rotors constructed of high-mechanic strength ceramics are detailed that include a sample compartment that maintains high pressures up to at least about 200 atmospheres (atm) and high temperatures up to about least about 300.degree. C. during operation. The rotor designs minimize pressure losses stemming from penetration over an extended period of time. The present invention makes possible a variety of in-situ high pressure, high temperature MAS NMR experiments not previously achieved in the prior art.

  3. Thermonuclear device

    International Nuclear Information System (INIS)

    Kuriyama, Masaaki; Yamamoto, Masahiro; Furuyama, Masayuki; Saito, Ryusei.

    1981-01-01

    Purpose: To enable the efficient and rapid cooling of a vacuum vessel by cooling with gas when the temperature of the vacuum vessel is higher than the boiling point of water and cooling with water when the temperature is lower than the boiling point of water. Constitution: A cooling pipe is provided through an insulating pipe on the outer periphery of a vacuum vessel. The cooling pipe communicates through a cooling gas valve and a coolant valve with a cooling gas supply device and a coolant supply device, and a heat exchanger is disposed at the pipe. When the vessel is higher than the boiling point of the coolant the coolant valve is closed and the cooling gas valve is opened and gas is supplied to cool the vessel. The gas is recoverd through a heat exchanger. On the other hand, when the temperature of vessel is lower than the boiling point of the coolant, the gas valve is closed, the coolant valve is opened, and the vessel is cooled with coolant. The vacuum vessel can be cooled for short time employing both the gas and the coolant together. (Yoshino, Y.)

  4. Rotary pneumatic valve

    Science.gov (United States)

    Hardee, Harry C.

    1991-01-01

    A rotary pneumatic valve which is thrust balanced and the pneumatic pressure developed produces only radial loads on the valve cylinder producing negligible resistance and thus minimal torque on the bearings of the valve. The valve is multiplexed such that at least two complete switching cycles occur for each revolution of the cylinder spindle.

  5. Mitral Valve Stenosis

    Science.gov (United States)

    ... the left ventricle from flowing backward. A defective heart valve fails to either open or close fully. Risk factors Mitral valve stenosis is less common today than it once was because the most common cause, ... other heart valve problems, mitral valve stenosis can strain your ...

  6. Aortic Valve Stenosis

    Science.gov (United States)

    ... most cases, doctors don't know why a heart valve fails to develop properly, so it isn't something you could have prevented. Calcium buildup on the valve. With age, heart valves may accumulate deposits of calcium (aortic valve ...

  7. Remote actuated valve implant

    Science.gov (United States)

    McKnight, Timothy E; Johnson, Anthony; Moise, Jr., Kenneth J; Ericson, Milton Nance; Baba, Justin S; Wilgen, John B; Evans, III, Boyd McCutchen

    2014-02-25

    Valve implant systems positionable within a flow passage, the systems having an inlet, an outlet, and a remotely activatable valve between the inlet and outlet, with the valves being operable to provide intermittent occlusion of the flow path. A remote field is applied to provide thermal or magnetic activation of the valves.

  8. Scissor thrust valve actuator

    Science.gov (United States)

    DeWall, Kevin G.; Watkins, John C; Nitzel, Michael E.

    2006-08-29

    Apparatus for actuating a valve includes a support frame and at least one valve driving linkage arm, one end of which is rotatably connected to a valve stem of the valve and the other end of which is rotatably connected to a screw block. A motor connected to the frame is operatively connected to a motor driven shaft which is in threaded screw driving relationship with the screw block. The motor rotates the motor driven shaft which drives translational movement of the screw block which drives rotatable movement of the valve driving linkage arm which drives translational movement of the valve stem. The valve actuator may further include a sensory control element disposed in operative relationship with the valve stem, the sensory control element being adapted to provide control over the position of the valve stem by at least sensing the travel and/or position of the valve stem.

  9. An active magnetic regenerator device

    DEFF Research Database (Denmark)

    2015-01-01

    A rotating active magnetic regenerator (AMR) device comprising two or more regenerator beds, a magnet arrangement and a valve arrangement. The valve arrangement comprises a plurality of valve elements arranged substantially immovably with respect to the regenerator beds along a rotational direction...

  10. Propionibacterium acnes endophthalmitis in Ahmed glaucoma valve.

    Science.gov (United States)

    Gutiérrez-Díaz, E; Montero-Rodríguez, M; Mencía-Gutiérrez, E; Fernández-González, M C; Pérez-Blázquez, E

    2001-01-01

    To report a case of Propionibacterium acnes endophthalmitis in a patient with an Ahmed glaucoma valve. A nine-year-old boy with bilateral congenital glaucoma, with an Ahmed glaucoma valve implanted in the left eye, had recurrent conjunctival dehiscence and endophthalmitis. Vitreous cultures demonstrated the presence of Propionibacterium acnes. This is the first reported case of Propionibacterium acnes endophthalmitis in an Ahmed glaucoma valve and the second one in a glaucoma drainage device. We strongly recommend using a patch graft to prevent and treat tube exposure. Conjunctival grafts may be useful to close the conjunctiva when there is marked scarring to prevent patch exposure and melting or extrusion.

  11. A review of design and modeling of magnetorheological valve

    Science.gov (United States)

    Abd Fatah, Abdul Yasser; Mazlan, Saiful Amri; Koga, Tsuyoshi; Zamzuri, Hairi; Zeinali, Mohammadjavad; Imaduddin, Fitrian

    2015-01-01

    Following recent rapid development of researches in utilizing Magnetorheological (MR) fluid, a smart material that can be magnetically controlled to change its apparent viscosity instantaneously, a lot of applications have been established to exploit the benefits and advantages of using the MR fluid. One of the most important applications for MR fluid in devices is the MR valve, where it uses the popular flow or valve mode among the available working modes for MR fluid. As such, MR valve is widely applied in a lot of hydraulic actuation and vibration reduction devices, among them are dampers, actuators and shock absorbers. This paper presents a review on MR valve, discusses on several design configurations and the mathematical modeling for the MR valve. Therefore, this review paper classifies the MR valve based on the coil configuration and geometrical arrangement of the valve, and focusing on four different mathematical models for MR valve: Bingham plastic, Herschel-Bulkley, bi-viscous and Herschel-Bulkley with pre-yield viscosity (HBPV) models for calculating yield stress and pressure drop in the MR valve. Design challenges and opportunities for application of MR fluid and MR valve are also highlighted in this review. Hopefully, this review paper can provide basic knowledge on design and modeling of MR valve, complementing other reviews on MR fluid, its applications and technologies.

  12. Miniaturization of environmental chemical assays in flowing systems: The lab-on-a-valve approach vis-à-vis lab-on-a-chip microfluidic devices

    DEFF Research Database (Denmark)

    Miró, Manuel; Hansen, Elo Harald

    2007-01-01

    The analytical capabilities of the microminiaturised lab-on-a-valve (LOV) module integrated into a microsequential injection (muSI) fluidic system in terms of analytical chemical performance, microfluidic handling and on-line sample processing are compared to those of the micro total analysis...... and the kinetics of the chemical reactions at will, LOV allows accommodation of reactions which, at least at the present stage, are not feasible by application of microfluidic LOC systems. Thus, in LOV one may take advantage of kinetic discriminations schemes, where even subtle differences in reactions...... are utilized for analytical purposes. Furthemore, it is also feasible to handle multi-step sequential reactions of divergent kinetics; to conduct multi-parametric determinations without manifold reconfiguration by utilization of the inherent open architecture of the micromachined unit for the implementation...

  13. Efficacy and safety of the pars plana clip in the Ahmed valve device inserted via the pars plana in patients with refractory glaucoma

    Directory of Open Access Journals (Sweden)

    Manuel Diaz-Llopis

    2010-05-01

    Full Text Available Manuel Diaz-Llopis1,2,3, David Salom1,3, Salvador García-Delpech1,2,3, Patricia Udaondo1,3, Jose Maria Millan3,5, J Fernando Arevalo61Department of Ophthalmology, La Fe University Hospital of Valencia, Valencia, Spain; 2Department of Ophthalmology of the Valencia University, Valencia, Spain; 3Biomedical Network Research Centre on Rare Diseases (CIBERER, Valencia, Spain; 4Catholic University San Vicente Martir, Valencia, Spain; 5Department of Genetics, La Fe University Hospital of Valencia, Valencia, Spain; 6Clinica Oftalmologica Centro Caracas, Retina and VItreous Service, Caracas, DC, VenezuelaPurpose: To evaluate the efficacy and safety of the pars plana clip (PPC in the Ahmed valve tube inserted via the pars plana in patients with secondary refractory glaucomas.Methods: Prospective and interventional case series that included 10 patients with secondary refractory glaucoma. The pars plana vitrectomy and the implant of the modified tube were performed during the same surgery. Control of intraocular pressure (IOP and the development of intra- and postoperative complications were evaluated during the follow-up.Results: Follow-up time was twelve months in all the patients. Control of IOP was achieved in 90% of patients, and 70% needed no antiglaucoma treatment. The complications that occurred were transient hypotony in three cases, choroidal detachment in two cases, and one case of intraocular hemorrhage. No case of tube extrusion or tube kink was observed.Conclusions: Our data suggests that implantation of the Ahmed tube modified with the PPC via the pars plana is safe and effective in patients with secondary refractory glaucomas. Keywords: pars plana clip, Ahmed valve, refractory glaucoma, pars plana vitrectomy

  14. A high performance magnetorheological valve with a meandering flow path

    International Nuclear Information System (INIS)

    Imaduddin, Fitrian; Amri Mazlan, Saiful; Azizi Abdul Rahman, Mohd; Zamzuri, Hairi; Ubaidillah; Ichwan, Burhanuddin

    2014-01-01

    The huge developments in the field of magnetorheological (MR) fluid-based devices will have a great influence on the future of mechatronic applications due to the ease of interfacing between electronic controls and the mechanical components that they provide. Among various MR fluid-based devices, an MR valve would be particularly significant for the development of other devices, if it could be successfully achieved. One of the most challenging obstacles to MR valve development is the difficulty of achieving device miniaturization while, at the same time, improving the achievable performance. This study demonstrates a novel design for an MR valve, using the meandering flow path approach in order to increase the effective area so that the MR fluid can be regulated within a small-sized valve. The meandering flow path is formed by combining multiple annular, radial and orifice flow channels. In order to analyze the valve performance, a mathematical model of the proposed MR valve is derived and combined with numerical simulation using the finite element method, with the intention of predicting the achievable pressure drop that can be generated by the valve. The predicted MR valve performances are then experimentally evaluated using an oscillation-disturbed bypass hydraulic cylinder. The simulation results show that the proposed MR valve design could yield substantial pressure drop improvement, which is confirmed by the experiment

  15. Which valve is which?

    Directory of Open Access Journals (Sweden)

    Pravin Saxena

    2015-01-01

    Full Text Available A 25-year-old man presented with a history of breathlessness for the past 2 years. He had a history of operation for Tetralogy of Fallot at the age of 5 years and history suggestive of Rheumatic fever at the age of 7 years. On echocardiographic examination, all his heart valves were severely regurgitating. Morphologically, all the valves were irreparable. The ejection fraction was 35%. He underwent quadruple valve replacement. The aortic and mitral valves were replaced by metallic valve and the tricuspid and pulmonary by tissue valve.

  16. Spin Torques in Systems with Spin Filtering and Spin Orbit Interaction

    KAUST Repository

    Ortiz Pauyac, Christian

    2016-06-19

    In the present thesis we introduce the reader to the field of spintronics and explore new phenomena, such as spin transfer torques, spin filtering, and three types of spin-orbit torques, Rashba, spin Hall, and spin swapping, which have emerged very recently and are promising candidates for a new generation of memory devices in computer technology. A general overview of these phenomena is presented in Chap. 1. In Chap. 2 we study spin transfer torques in tunnel junctions in the presence of spin filtering. In Chap. 3 we discuss the Rashba torque in ferromagnetic films, and in Chap. 4 we study spin Hall effect and spin swapping in ferromagnetic films, exploring the nature of spin-orbit torques based on these mechanisms. Conclusions and perspectives are summarized in Chap. 5.

  17. Reliability Evaluation of Concentric Butterfly Valve Using Statistical Hypothesis Test

    International Nuclear Information System (INIS)

    Chang, Mu Seong; Choi, Jong Sik; Choi, Byung Oh; Kim, Do Sik

    2015-01-01

    A butterfly valve is a type of flow-control device typically used to regulate a fluid flow. This paper presents an estimation of the shape parameter of the Weibull distribution, characteristic life, and B10 life for a concentric butterfly valve based on a statistical analysis of the reliability test data taken before and after the valve improvement. The difference in the shape and scale parameters between the existing and improved valves is reviewed using a statistical hypothesis test. The test results indicate that the shape parameter of the improved valve is similar to that of the existing valve, and that the scale parameter of the improved valve is found to have increased. These analysis results are particularly useful for a reliability qualification test and the determination of the service life cycles

  18. Reliability Evaluation of Concentric Butterfly Valve Using Statistical Hypothesis Test

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Mu Seong; Choi, Jong Sik; Choi, Byung Oh; Kim, Do Sik [Korea Institute of Machinery and Materials, Daejeon (Korea, Republic of)

    2015-12-15

    A butterfly valve is a type of flow-control device typically used to regulate a fluid flow. This paper presents an estimation of the shape parameter of the Weibull distribution, characteristic life, and B10 life for a concentric butterfly valve based on a statistical analysis of the reliability test data taken before and after the valve improvement. The difference in the shape and scale parameters between the existing and improved valves is reviewed using a statistical hypothesis test. The test results indicate that the shape parameter of the improved valve is similar to that of the existing valve, and that the scale parameter of the improved valve is found to have increased. These analysis results are particularly useful for a reliability qualification test and the determination of the service life cycles.

  19. Bioprosthetic Valve Fracture Improves the Hemodynamic Results of Valve-in-Valve Transcatheter Aortic Valve Replacement.

    Science.gov (United States)

    Chhatriwalla, Adnan K; Allen, Keith B; Saxon, John T; Cohen, David J; Aggarwal, Sanjeev; Hart, Anthony J; Baron, Suzanne J; Dvir, Danny; Borkon, A Michael

    2017-07-01

    Valve-in-valve (VIV) transcatheter aortic valve replacement (TAVR) may be less effective in small surgical valves because of patient/prosthesis mismatch. Bioprosthetic valve fracture (BVF) using a high-pressure balloon can be performed to facilitate VIV TAVR. We report data from 20 consecutive clinical cases in which BVF was successfully performed before or after VIV TAVR by inflation of a high-pressure balloon positioned across the valve ring during rapid ventricular pacing. Hemodynamic measurements and calculation of the valve effective orifice area were performed at baseline, immediately after VIV TAVR, and after BVF. BVF was successfully performed in 20 patients undergoing VIV TAVR with balloon-expandable (n=8) or self-expanding (n=12) transcatheter valves in Mitroflow, Carpentier-Edwards Perimount, Magna and Magna Ease, Biocor Epic and Biocor Epic Supra, and Mosaic surgical valves. Successful fracture was noted fluoroscopically when the waist of the balloon released and by a sudden drop in inflation pressure, often accompanied by an audible snap. BVF resulted in a reduction in the mean transvalvular gradient (from 20.5±7.4 to 6.7±3.7 mm Hg, P valve effective orifice area (from 1.0±0.4 to 1.8±0.6 cm 2 , P valves to facilitate VIV TAVR with either balloon-expandable or self-expanding transcatheter valves and results in reduced residual transvalvular gradients and increased valve effective orifice area. © 2017 American Heart Association, Inc.

  20. Resonant Tunneling Spin Pump

    Science.gov (United States)

    Ting, David Z.

    2007-01-01

    The resonant tunneling spin pump is a proposed semiconductor device that would generate spin-polarized electron currents. The resonant tunneling spin pump would be a purely electrical device in the sense that it would not contain any magnetic material and would not rely on an applied magnetic field. Also, unlike prior sources of spin-polarized electron currents, the proposed device would not depend on a source of circularly polarized light. The proposed semiconductor electron-spin filters would exploit the Rashba effect, which can induce energy splitting in what would otherwise be degenerate quantum states, caused by a spin-orbit interaction in conjunction with a structural-inversion asymmetry in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. Theoretical studies have suggested the possibility of devices in which electron energy states would be split by the Rashba effect and spin-polarized currents would be extracted by resonant quantum-mechanical tunneling.

  1. A general circuit model for spintronic devices under electric and magnetic fields

    KAUST Repository

    Alawein, Meshal

    2017-10-25

    In this work, we present a circuit model of diffusive spintronic devices capable of capturing the effects of both electric and magnetic fields. Starting from a modified version of the well-established drift-diffusion equations, we derive general equivalent circuit models of semiconducting/metallic nonmagnets and metallic ferromagnets. In contrast to other models that are based on steady-state transport equations which might also neglect certain effects such as thermal fluctuations, spin dissipation in the ferromagnets, and spin precession under magnetic fields, our model incorporates most of the important physics and is based on a time-dependent formulation. An application of our model is shown through simulations of a nonlocal spin-valve under the presence of a magnetic field, where we reproduce experimental results of electrical measurements that demonstrate the phenomena of spin precession and dephasing (“Hanle effect”).

  2. Mitral Valve Prolapse

    Science.gov (United States)

    ... valve syndrome . What happens during MVP? Watch an animation of mitral valve prolapse When the heart pumps ( ... our brochures Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  3. Problem: Mitral Valve Regurgitation

    Science.gov (United States)

    ... each time the left ventricle contracts. Watch an animation of mitral valve regurgitation A leaking mitral valve ... Not Alone Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  4. Problem: Heart Valve Regurgitation

    Science.gov (United States)

    ... should be completely closed For example: Watch an animation of mitral valve regurgitation A leaking mitral valve ... Not Alone Popular Articles 1 Understanding Blood Pressure Readings 2 Sodium and Salt 3 Heart Attack Symptoms ...

  5. Aortic valve surgery - open

    Science.gov (United States)

    ... gov/ency/article/007408.htm Aortic valve surgery - open To use the sharing features on this page, ... separates the heart and aorta. The aortic valve opens so blood can flow out. It then closes ...

  6. Corrosion of valve metals

    International Nuclear Information System (INIS)

    Draley, J.E.

    1976-01-01

    A general survey related to the corrosion of valve metals or film-forming metals. The way these metals corrode with some general examples is described. Valve metals form relatively perfect oxide films with little breakdown or leakage when anodized

  7. Mitral valve surgery - open

    Science.gov (United States)

    ... Taking warfarin (Coumadin) References Otto CM, Bonow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ... A.M. Editorial team. Heart Surgery Read more Heart Valve Diseases Read more Mitral Valve Prolapse Read more A. ...

  8. Swing check valve

    International Nuclear Information System (INIS)

    Eminger, H.E.

    1977-01-01

    A swing check valve which includes a valve body having an inlet and outlet is described. A recess in the valve body designed to hold a seal ring and a check valve disc swingable between open and closed positions. The disc is supported by a high strength wire secured at one end in a support spacer pinned through bearing blocks fixed to the valve body and at its other end in a groove formed on the outer peripheral surface of the disc. The parts are designed and chosen such to provide a lightweight valve disc which is held open by minimum velocity of fluid flowing through the valve which thus reduces oscillations and accompanying wear of bearings supporting the valve operating parts. (Auth.)

  9. Spin-current emission governed by nonlinear spin dynamics.

    Science.gov (United States)

    Tashiro, Takaharu; Matsuura, Saki; Nomura, Akiyo; Watanabe, Shun; Kang, Keehoon; Sirringhaus, Henning; Ando, Kazuya

    2015-10-16

    Coupling between conduction electrons and localized magnetization is responsible for a variety of phenomena in spintronic devices. This coupling enables to generate spin currents from dynamical magnetization. Due to the nonlinearity of magnetization dynamics, the spin-current emission through the dynamical spin-exchange coupling offers a route for nonlinear generation of spin currents. Here, we demonstrate spin-current emission governed by nonlinear magnetization dynamics in a metal/magnetic insulator bilayer. The spin-current emission from the magnetic insulator is probed by the inverse spin Hall effect, which demonstrates nontrivial temperature and excitation power dependences of the voltage generation. The experimental results reveal that nonlinear magnetization dynamics and enhanced spin-current emission due to magnon scatterings are triggered by decreasing temperature. This result illustrates the crucial role of the nonlinear magnon interactions in the spin-current emission driven by dynamical magnetization, or nonequilibrium magnons, from magnetic insulators.

  10. Spin-photon entangling diode

    DEFF Research Database (Denmark)

    Flindt, Christian; Sørensen, A. S.; Lukin, M. D.

    2007-01-01

    We propose a semiconductor device that can electrically generate entangled electron spin-photon states, providing a building block for entanglement of distant spins. The device consists of a p-i-n diode structure that incorporates a coupled double quantum dot. We show that electronic control of t...

  11. Mitral Valve Prolapse

    Science.gov (United States)

    Mitral valve prolapse (MVP) occurs when one of your heart's valves doesn't work properly. The flaps of the valve are "floppy" and ... to run in families. Most of the time, MVP doesn't cause any problems. Rarely, blood can ...

  12. Overflow control valve

    International Nuclear Information System (INIS)

    Kessinger, B.A.; Hundal, R.; Parlak, E.A.

    1982-01-01

    An overflow control valve for use in a liquid sodium coolant pump tank which can be remotely engaged with and disengaged from the pump tank wall to thereby permit valve removal. An actuating shaft for controlling the valve also has means for operating a sliding cylinder against a spring to retract the cylinder from sealing contact with the pump tank nozzle. (author)

  13. Fluid control valves

    International Nuclear Information System (INIS)

    Rankin, J.

    1980-01-01

    A fluid control valve is described in which it is not necessary to insert a hand or a tool into the housing to remove the valve seat. Such a valve is particularly suitable for the control of radioactive fluids since maintenance by remote control is possible. (UK)

  14. A remote control valve

    International Nuclear Information System (INIS)

    Cachard, Maurice de; Dumont, Maurice.

    1976-01-01

    This invention concerns a remote control valve for shutting off or distributing a fluid flowing at a high rate and low pressure. Among the different valves at present in use, electric valves are the most recommended for remote control but their reliability is uncertain and they soon become costly when large diameter valves are used. The valve described in this invention does away with this drawback owing to its simplicity and the small number of moving parts, this makes it particularly reliable. It mainly includes: a tubular body fitted with at least one side opening; at least one valve wedge for this opening, coaxial with the body, and mobile; a mobile piston integral with this wedge. Several valves to the specifications of this invention can be fitted in series (a shut-off valve can be used in conjunction with one or more distribution valves). The fitting and maintenance of the valve is very simple owing to its design. It can be fabricated in any material such as metals, alloys, plastics and concrete. The structure of the valve prevents the flowing fluid from coming into contact with the outside environment, thereby making it particularly suitable in the handling of dangerous or corrosive fluids. Finally, the opening and shutting of the valve occurs slowly, thereby doing away with the water hammer effect so frequent in large bore pipes [fr

  15. Heart Valve Diseases

    Science.gov (United States)

    Your heart has four valves. Normally, these valves open to let blood flow through or out of your heart, and then shut to keep it from flowing ... close tightly. It's one of the most common heart valve conditions. Sometimes it causes regurgitation. Stenosis - when ...

  16. Spin diffusion and torques in disordered antiferromagnets

    KAUST Repository

    Manchon, Aurelien

    2017-02-01

    We have developed a drift-diffusion equation of spin transport in collinear bipartite metallic antiferromagnets. Starting from a model tight-binding Hamiltonian, we obtain the quantum kinetic equation within Keldysh formalism and expand it to the lowest order in spatial gradient using Wigner expansion method. In the diffusive limit, these equations track the spatio-temporal evolution of the spin accumulations and spin currents on each sublattice of the antiferromagnet. We use these equations to address the nature of the spin transfer torque in (i) a spin-valve composed of a ferromagnet and an antiferromagnet, (ii) a metallic bilayer consisting of an antiferromagnet adjacent to a heavy metal possessing spin Hall effect, and in (iii) a single antiferromagnet possessing spin Hall effect. We show that the latter can experience a self-torque thanks to the non-vanishing spin Hall effect in the antiferromagnet.

  17. Spin diffusion and torques in disordered antiferromagnets

    KAUST Repository

    Manchon, Aurelien

    2017-01-01

    We have developed a drift-diffusion equation of spin transport in collinear bipartite metallic antiferromagnets. Starting from a model tight-binding Hamiltonian, we obtain the quantum kinetic equation within Keldysh formalism and expand it to the lowest order in spatial gradient using Wigner expansion method. In the diffusive limit, these equations track the spatio-temporal evolution of the spin accumulations and spin currents on each sublattice of the antiferromagnet. We use these equations to address the nature of the spin transfer torque in (i) a spin-valve composed of a ferromagnet and an antiferromagnet, (ii) a metallic bilayer consisting of an antiferromagnet adjacent to a heavy metal possessing spin Hall effect, and in (iii) a single antiferromagnet possessing spin Hall effect. We show that the latter can experience a self-torque thanks to the non-vanishing spin Hall effect in the antiferromagnet.

  18. Spin tunneling and manipulation in nanostructures.

    Science.gov (United States)

    Sherman, E Ya; Ban, Yue; Gulyaev, L V; Khomitsky, D V

    2012-09-01

    The results for joint effects of tunneling and spin-orbit coupling on spin dynamics in nanostructures are presented for systems with discrete and continuous spectra. We demonstrate that tunneling plays the crucial role in the spin dynamics and the abilities of spin manipulation by external electric field. This result can be important for design of nanostructures-based spintronics devices.

  19. Glovebox pressure relief and check valve

    International Nuclear Information System (INIS)

    Blaedel, K.L.

    1986-01-01

    This device is a combined pressure relief valve and check valve providing overpressure protection and preventing back flow into an inert atmosphere enclosure. The pressure relief is embodied by a submerged vent line in a mercury reservior, the releif pressure being a function of the submerged depth. The pressure relief can be vented into an exhaust system and the relieving pressure is only slightly influenced by the varying pressure in the exhaust system. The check valve is embodied by a ball which floats on the mercury column and contacts a seat whenever vacuum exists within the glovebox enclosure. Alternatively, the check valve is embodied by a vertical column of mercury, the maximum back pressure being a function of the height of the column of mercury

  20. Glovebox pressure relief and check valve

    Energy Technology Data Exchange (ETDEWEB)

    Blaedel, K.L.

    1986-03-17

    This device is a combined pressure relief valve and check valve providing overpressure protection and preventing back flow into an inert atmosphere enclosure. The pressure relief is embodied by a submerged vent line in a mercury reservior, the releif pressure being a function of the submerged depth. The pressure relief can be vented into an exhaust system and the relieving pressure is only slightly influenced by the varying pressure in the exhaust system. The check valve is embodied by a ball which floats on the mercury column and contacts a seat whenever vacuum exists within the glovebox enclosure. Alternatively, the check valve is embodied by a vertical column of mercury, the maximum back pressure being a function of the height of the column of mercury.

  1. Heavy gas valves

    Energy Technology Data Exchange (ETDEWEB)

    Steier, L [Vereinigte Armaturen Gesellschaft m.b.H., Mannheim (Germany, F.R.)

    1979-01-01

    Heavy gas valves must comply with special requirements. Apart from absolute safety in operation there are stringent requirements for material, sealing and ease of operation even in the most difficult conditions. Ball valves and single plate pipe gate valves lateral sealing rings have a dual, double sided sealing effect according to the GROVE sealing system. Single plate gate valves with lateral protective plates are suitable preferably for highly contaminated media. Soft sealing gate valves made of cast iron are used for low pressure applications.

  2. Inpile honing of Sizewell primary selector valve housings

    International Nuclear Information System (INIS)

    Grindrod, A.; Ward, R.G.

    1976-03-01

    Difficulties have been experienced at Sizewell power station with the removal and replacement of several of the primary selector valves fitted in the reactors, during the annual maintenance programme. An inpile honing device is described which was specifically designed and developed to facilitate the restoration of the inner sealing faces of the valve housings. (author)

  3. Electroluminescence color tuning between green and red from metal-oxide-semiconductor devices fabricated by spin-coating of rare-earth (terbium + europium) organic compounds on silicon

    Science.gov (United States)

    Matsuda, Toshihiro; Hattori, Fumihiro; Iwata, Hideyuki; Ohzone, Takashi

    2018-04-01

    Color tunable electroluminescence (EL) from metal-oxide-semiconductor devices with the rare-earth elements Tb and Eu is reported. Organic compound liquid sources of (Tb + Ba) and Eu with various Eu/Tb ratios from 0.001 to 0.4 were spin-coated on an n+-Si substrate and annealed to form an oxide insulator layer. The EL spectra had only peaks corresponding to the intrashell Tb3+/Eu3+ transitions in the spectral range from green to red, and the intensity ratio of the peaks was appropriately tuned using the appropriate Eu/Tb ratios in liquid sources. Consequently, the EL emission colors linearly changed from yellowish green to yellowish orange and eventually to reddish orange on the CIE chromaticity diagram. The gate current +I G current also affected the EL colors for the medium-Eu/Tb-ratio device. The structure of the surface insulator films analyzed by cross-sectional transmission electron microscopy (TEM), X-ray diffraction (XRD) analysis, and X-ray photoelectron spectroscopy (XPS) has four layers, namely, (Tb4O7 + Eu2O3), [Tb4O7 + Eu2O3 + (Tb/Eu/Ba)SiO x ], (Tb/Eu/Ba)SiO x , and SiO x -rich oxide. The EL mechanism proposed is that electrons injected from the Si substrate into the SiO x -rich oxide and Tb/Eu/Ba-silicate layers become hot electrons accelerated in a high electric field, and then these hot electrons excite Tb3+ and Eu3+ ions in the Tb4O7/Eu2O3 layers resulting in EL emission from Tb3+ and Eu3+ intrashell transitions.

  4. Role of motive forces for the spin torque transfer for nano-structures

    Science.gov (United States)

    Barnes, Stewart

    2009-03-01

    Despite an announced imminent commercial realization of spin transfer random access memory (SPRAM) the current theory evolved from that of Slonczewski [1,2] does not conserve energy. Barnes and Maekawa [3] have shown, in order correct this defect, forces which originate from the spin rather than the charge of an electron must be accounted for, this leading to the concept of spin-motive-forces (smf) which must appear in Faraday's law and which significantly modifies the theory for spin-valves and domain wall devices [4]. A multi-channel theory in which these smf's redirect the spin currents will be described. In nano-structures it is now well known that the Kondo effect is reflected by conductance peaks. In essence, the spin degrees of freedom are used to enhance conduction. In a system with nano-magnets and a Coulomb blockade [5] the similar spin channels can be the only means of effective conduction. This results in a smf which lasts for minutes and an enormous magneto-resistance [5]. This implies the possibility of ``single electron memory'' in which the magnetic state is switched by a single electron. [4pt] [1] J. C. Slonczewski, Current-Driven Excitation of Magnetic Multilayers J. Magn. Magn. Mater. 159, L1 (1996). [0pt] [2] Y. Tserkovnyak, A. Brataas, G. E. W. Bauer, and B. I. Halperin, Nonlocal magnetization dynamics in ferromagnetic heterostructures, Rev. Mod. Phys. 77, 1375 (2005). [0pt] [3] S. E. Barnes and S. Maekawa, Generalization of Faraday's Law to Include Nonconservative Spin Forces Phys. Rev. Lett. 98, 246601 (2007); S. E. Barnes and S. Maekawa, Currents induced by domain wall motion in thin ferromagnetic wires. arXiv:cond-mat/ 0410021v1 (2004). [0pt] [4] S. E., Barnes, Spin motive forces, measurement, and spin-valves. J. Magn. Magn. Mat. 310, 2035-2037 (2007); S. E. Barnes, J. Ieda. J and S. Maekawa, Magnetic memory and current amplification devices using moving domain walls. Appl. Phys. Lett. 89, 122507 (2006). [0pt] [5] Pham-Nam Hai, Byung-Ho Yu

  5. Hybrid superconducting-magnetic memory device using competing order parameters.

    Science.gov (United States)

    Baek, Burm; Rippard, William H; Benz, Samuel P; Russek, Stephen E; Dresselhaus, Paul D

    2014-05-28

    In a hybrid superconducting-magnetic device, two order parameters compete, with one type of order suppressing the other. Recent interest in ultra-low-power, high-density cryogenic memories has spurred new efforts to simultaneously exploit superconducting and magnetic properties so as to create novel switching elements having these two competing orders. Here we describe a reconfigurable two-layer magnetic spin valve integrated within a Josephson junction. Our measurements separate the suppression in the superconducting coupling due to the exchange field in the magnetic layers, which causes depairing of the supercurrent, from the suppression due to the stray magnetic field. The exchange field suppression of the superconducting order parameter is a tunable and switchable behaviour that is also scalable to nanometer device dimensions. These devices demonstrate non-volatile, size-independent switching of Josephson coupling, in magnitude as well as phase, and they may enable practical nanoscale superconducting memory devices.

  6. Long annealing effect on spin Seebeck devices fabricated using Ce x Y3- x Fe5O12 deposited by metal-organic decomposition

    Science.gov (United States)

    Ono, Tatsuyoshi; Hirata, Satoshi; Amemiya, Yoshiteru; Tabei, Tetsuo; Yokoyama, Shin

    2018-04-01

    The effects of Ce content and annealing temperature on the electromotive force produced by spin Seebeck devices fabricated using Ce x Y3- x Fe5O12 deposited by metal-organic decomposition was investigated. The Ce content was first varied (x = 0,1,2,3) for a fixed annealing condition of 3 h at 900 °C. It was found that increasing the Ce content led to a decrease in electromotive force, which meant that x = 0 was the optimum Ce content. Next, the effect of annealing temperature was investigated for a Ce1Y2Fe5O12 film for an annealing time of 14 h. The highest electromotive force of 24.0 µV/50 °C was obtained for a sample annealed for 14 h at 800 °C, although the X-ray diffraction peaks were weaker than those for a sample annealed for 14 h at 950 °C.

  7. Relief valve testing study

    International Nuclear Information System (INIS)

    BROMM, R.D.

    2001-01-01

    Reclosing pressure-actuated valves, commonly called relief valves, are designed to relieve system pressure once it reaches the set point of the valve. They generally operate either proportional to the differential between their set pressure and the system pressure (gradual lift) or by rapidly opening fully when the set pressure is reached (pop action). A pop action valve allows the maximum fluid flow through the valve when the set pressure is reached. A gradual lift valve allows fluid flow in proportion to how much the system pressure has exceeded the set pressure of the valve (in the case of pressure relief) or has decreased below the set pressure (vacuum relief). These valves are used to protect systems from over and under pressurization. They are used on boilers, pressure vessels, piping systems and vacuum systems to prevent catastrophic failures of these systems, which can happen if they are under or over pressurized beyond the material tolerances. The construction of these valves ranges from extreme precision of less than a psi tolerance and a very short lifetime to extremely robust construction such as those used on historic railroad steam engines that are designed operate many times a day without changing their set pressure when the engines are operating. Relief valves can be designed to be immune to the effects of back pressure or to be vulnerable to it. Which type of valve to use depends upon the design requirements of the system

  8. A novel implantable glaucoma valve using ferrofluid.

    Directory of Open Access Journals (Sweden)

    Eleftherios I Paschalis

    Full Text Available PURPOSE: To present a novel design of an implantable glaucoma valve based on ferrofluidic nanoparticles and to compare it with a well-established FDA approved valve. SETTING: Massachusetts Eye & Ear Infirmary, Boston, USA. METHODS: A glaucoma valve was designed using soft lithography techniques utilizing a water-immiscible magnetic fluid (ferrofluid as a pressure-sensitive barrier to aqueous flow. Two rare earth micro magnets were used to calibrate the opening and closing pressure. In-vitro flow measurements were performed to characterize the valve and to compare it to Ahmed™ glaucoma valve. The reliability and predictability of the new valve was verified by pressure/flow measurements over a period of three months and X-ray diffraction (XRD analysis over a period of eight weeks. In vivo assessment was performed in three rabbits. RESULTS: In the in vitro experiments, the opening and closing pressures of the valve were 10 and 7 mmHg, respectively. The measured flow/pressure response was linearly proportional and reproducible over a period of three months (1.8 µl/min at 12 mmHg; 4.3 µl/min at 16 mmHg; 7.6 µl/min at 21 mmHg. X-ray diffraction analysis did not show oxidization of the ferrofluid when exposed to water or air. Preliminary in vivo results suggest that the valve is biocompatible and can control the intraocular pressure in rabbits. CONCLUSIONS: The proposed valve utilizes ferrofluid as passive, tunable constriction element to provide highly predictable opening and closing pressures while maintaining ocular tone. The ferrofluid maintained its magnetic properties in the aqueous environment and provided linear flow to pressure response. Our in-vitro tests showed reliable and reproducible results over a study period of three months. Preliminary in-vivo results were very promising and currently more thorough investigation of this device is underway.

  9. Dependency of tunneling magnetoresistance ratio on Pt seed-layer thickness for double MgO perpendicular magnetic tunneling junction spin-valves with a top Co2Fe6B2 free layer ex-situ annealed at 400 °C.

    Science.gov (United States)

    Takemura, Yasutaka; Lee, Du-Yeong; Lee, Seung-Eun; Park, Jea-Gun

    2016-12-02

    For the double MgO based perpendicular magnetic tunneling junction (p-MTJ) spin-valves with a top Co 2 Fe 6 B 2 free layer ex situ annealed at 400 °C, the tunneling-magnetoresistance ratio (TMR) strongly depended on the platinum (Pt) seed layer thickness (t Pt ): it peaked (∼134%) at a specific t Pt (3.3 nm). The TMR ratio was initially and slightly increased from 113%-134% by the enhancement of the magnetic moment of the Co 2 Fe 6 B 2 pinned layer when t Pt increased from 2.0-3.3 nm, and then rapidly decreased from 134%-38.6% by the degrading face-centered-cubic crystallinity of the MgO tunneling barrier when t Pt increased from 3.3-14.3 nm.

  10. Spin-polarized transport through single-molecule magnet Mn6 complexes

    KAUST Repository

    Cremades, Eduard

    2013-01-01

    The coherent transport properties of a device, constructed by sandwiching a Mn6 single-molecule magnet between two gold surfaces, are studied theoretically by using the non-equilibrium Green\\'s function approach combined with density functional theory. Two spin states of such Mn6 complexes are explored, namely the ferromagnetically coupled configuration of the six MnIII cations, leading to the S = 12 ground state, and the low S = 4 spin state. For voltages up to 1 volt the S = 12 ground state shows a current one order of magnitude larger than that of the S = 4 state. Furthermore this is almost completely spin-polarized, since the Mn6 frontier molecular orbitals for S = 12 belong to the same spin manifold. As such the high-anisotropy Mn6 molecule appears as a promising candidate for implementing, at the single molecular level, both spin-switches and low-temperature spin-valves. © 2013 The Royal Society of Chemistry.

  11. Transcatheter mitral valve repair in osteogenesis imperfecta associated mitral valve regurgitation.

    Science.gov (United States)

    van der Kley, Frank; Delgado, Victoria; Ajmone Marsan, Nina; Schalij, Martin J

    2014-08-01

    Osteogenesis imperfecta is associated with increased prevalence of significant mitral valve regurgitation. Surgical mitral valve repair and replacement are feasible but are associated with increased risk of bleeding and dehiscence of implanted valves may occur more frequently. The present case report describes the outcomes of transcatheter mitral valve repair in a patient with osteogenesis imperfecta. A 60 year-old patient with osteogenesis imperfecta and associated symptomatic moderate to severe mitral regurgitation underwent transthoracic echocardiography which showed a nondilated left ventricle with preserved systolic function and moderate to severe mitral regurgitation. On transoesophageal echocardiography the regurgitant jet originated between the anterolateral scallops of the anterior and posterior leaflets (A1-P1). Considering the comorbidities associated with osteogenesis imperfecta the patient was accepted for transcatheter mitral valve repair using the Mitraclip device (Abbott vascular, Menlo, CA). Under fluoroscopy and 3D transoesophageal echocardiography guidance, a Mitraclip device was implanted between the anterolateral and central scallops with significant reduction of mitral regurgitation. The postoperative evolution was uneventful. At one month follow-up, transthoracic echocardiography showed a stable position of the Mitraclip device with no mitral regurgitation. Transcatheter mitral valve repair is feasible and safe in patients with osteogenesis imperfecta and associated symptomatic significant mitral regurgitation. Copyright © 2014 Australian and New Zealand Society of Cardiac and Thoracic Surgeons (ANZSCTS) and the Cardiac Society of Australia and New Zealand (CSANZ). Published by Elsevier B.V. All rights reserved.

  12. Vascular complications associated with transcatheter aortic valve replacement.

    Science.gov (United States)

    Sardar, M Rizwan; Goldsweig, Andrew M; Abbott, J Dawn; Sharaf, Barry L; Gordon, Paul C; Ehsan, Afshin; Aronow, Herbert D

    2017-06-01

    Transcatheter aortic valve replacement (TAVR) is now an accepted pathway for aortic valve replacement for patients who are at prohibitive, severe and intermediate risk for traditional aortic valve surgery. However, with this rising uptrend and adaptation of this new technology, vascular complications and their management remain an Achilles heel for percutaneous aortic valve replacement. The vascular complications are an independent predictor of mortality for patients undergoing TAVR. Early recognition of these complications and appropriate management is paramount. In this article, we review the most commonly encountered vascular complications associated with currently approved TAVR devices and their optimal percutaneous management techniques.

  13. Designed pneumatic valve actuators for controlled droplet breakup and generation.

    Science.gov (United States)

    Choi, Jae-Hoon; Lee, Seung-Kon; Lim, Jong-Min; Yang, Seung-Man; Yi, Gi-Ra

    2010-02-21

    The dynamic breakup of emulsion droplets was demonstrated in double-layered microfluidic devices equipped with designed pneumatic actuators. Uniform emulsion droplets, produced by shearing at a T-junction, were broken into smaller droplets when they passed downstream through constrictions formed by a pneumatically actuated valve in the upper control layer. The valve-assisted droplet breakup was significantly affected by the shape and layout of the control valves on the emulsion flow channel. Interestingly, by actuating the pneumatic valve immediately above the T-junction, the sizes of the emulsion droplets were controlled precisely in a programmatic manner that produced arrays of uniform emulsion droplets in various sizes and dynamic patterns.

  14. Microwave frequency tuning in heterogeneous spin torque oscillator with perpendicular polarizer: A macrospin study

    Science.gov (United States)

    Bhoomeeswaran, H.; Vivek, T.; Sabareesan, P.

    2018-04-01

    In this article, we have theoretically devised a Spin Torque Nano Oscillator (STNO) with perpendicular polarizer using macro spin model. The devised spin valve structure is heterogeneous (i.e.) it is made of two different ferromagnetic materials [Co and its alloy CoFeB]. The dynamics of magnetization provoked by spin transfer torque is studied numerically by solving the famous Landau-Lifshitz-Gilbert-Slonczewski [LLGS] equation. The results are obtained for the perpendicular polarizer and for that particular out of plane orientation we vary the free layer angle from 10° to 90°. The obtained results are highly appealing, because frequency range is available in all the tilt angles of free layer and it is exceptionally tunable in all free layer tilt angles with zero applied field. Moreover, the utmost operating frequency of about 83.3 GHz and its corresponding power of 4.488 µW/mA2/GHz is acquired for the free layer tilt angle θ = 90° with the solid applied current density of 10 × 1010 A/m2. Also, our device emits high quality factor of about 396, which is remarkably desirable for making devices. These pioneering results provides a significant development for future spintronic based devices.

  15. Reduced-impact sliding pressure control valve for pneumatic hammer drill

    Science.gov (United States)

    Polsky, Yarom [Oak Ridge, TN; Grubelich, Mark C [Albuquerque, NM; Vaughn, Mark R [Albuquerque, NM

    2012-05-15

    A method and means of minimizing the effect of elastic valve recoil in impact applications, such as percussive drilling, where sliding spool valves used inside the percussive device are subject to poor positioning control due to elastic recoil effects experienced when the valve impacts a stroke limiting surface. The improved valve design reduces the reflected velocity of the valve by using either an energy damping material, or a valve assembly with internal damping built-in, to dissipate the compression stress wave produced during impact.

  16. Durability Tests of Ball Valve Prototype with Flowmeter Operation

    Science.gov (United States)

    Rogula, J.; Romanik, G.

    2018-02-01

    The results of the investigation of the prototypical ball valve are presented in this article. The innovation of the tested valve is a ball with a built-in measuring orifice. The valve has been subjected to durability tests. Leakage under three temperatures: ambient, -30°C and +100°C was analyzed. Sealing elements of the valve were tested for roughness and deviation of shape before and after the cycles of operation. Ball valve operation means cycles of open/close. It was planned to perform 1000 cycles at each temperature condition accordingly. Tests of the valve were performed under gas pressure equal to 10 MPa. The research was carried out under the Operational Program "Intelligent Development" (POIR 01.01.01-00-0013 / 15 "Development of devices for measurement of media flow on industrial trunk-lines".

  17. Development of magnetic drive packless valves for commercial purpose

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Seong Tae; Choi, Yoon Dong; Jeong, Ji Young [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1995-12-01

    A study on development of magnetic drive packless valves for commercial purpose showed the results as follows; A. Maximization of torque (1) Arranging method of magnets (2) Effects on the distance between magnetic holders (3) Improvement of the valve disc for the torque maximization. B. Study on the high pressure structure of the valve (1) Analysis of the pressure-resisting structure of the magnetic power transmitting device (2) Calculation model and program (a) Calculation model (b) Program used in calculation (3) Structure analysis and verification test for the pressurized plate. C. Study on the valve compacting. D. Technical specification for the valve manufacture. E. Inspection and test method for valve. 10 tabs., 10 figs. (Author).

  18. Development of magnetic drive packless valves for commercial purpose

    International Nuclear Information System (INIS)

    Hwang, Seong Tae; Choi, Yoon Dong; Jeong, Ji Young

    1995-12-01

    A study on development of magnetic drive packless valves for commercial purpose showed the results as follows; A. Maximization of torque (1) Arranging method of magnets (2) Effects on the distance between magnetic holders (3) Improvement of the valve disc for the torque maximization. B. Study on the high pressure structure of the valve (1) Analysis of the pressure-resisting structure of the magnetic power transmitting device (2) Calculation model and program (a) Calculation model (b) Program used in calculation (3) Structure analysis and verification test for the pressurized plate. C. Study on the valve compacting. D. Technical specification for the valve manufacture. E. Inspection and test method for valve. 10 tabs., 10 figs. (Author)

  19. Spin-Wave Diode

    Directory of Open Access Journals (Sweden)

    Jin Lan (兰金

    2015-12-01

    Full Text Available A diode, a device allowing unidirectional signal transmission, is a fundamental element of logic structures, and it lies at the heart of modern information systems. The spin wave or magnon, representing a collective quasiparticle excitation of the magnetic order in magnetic materials, is a promising candidate for an information carrier for the next-generation energy-saving technologies. Here, we propose a scalable and reprogrammable pure spin-wave logic hardware architecture using domain walls and surface anisotropy stripes as waveguides on a single magnetic wafer. We demonstrate theoretically the design principle of the simplest logic component, a spin-wave diode, utilizing the chiral bound states in a magnetic domain wall with a Dzyaloshinskii-Moriya interaction, and confirm its performance through micromagnetic simulations. Our findings open a new vista for realizing different types of pure spin-wave logic components and finally achieving an energy-efficient and hardware-reprogrammable spin-wave computer.

  20. Metallic spintronic devices

    CERN Document Server

    Wang, Xiaobin

    2014-01-01

    Metallic Spintronic Devices provides a balanced view of the present state of the art of metallic spintronic devices, addressing both mainstream and emerging applications from magnetic tunneling junction sensors and spin torque oscillators to spin torque memory and logic. Featuring contributions from well-known and respected industrial and academic experts, this cutting-edge work not only presents the latest research and developments but also: Describes spintronic applications in current and future magnetic recording devicesDiscusses spin-transfer torque magnetoresistive random-access memory (STT-MRAM) device architectures and modelingExplores prospects of STT-MRAM scaling, such as detailed multilevel cell structure analysisInvestigates spintronic device write and read optimization in light of spintronic memristive effectsConsiders spintronic research directions based on yttrium iron garnet thin films, including spin pumping, magnetic proximity, spin hall, and spin Seebeck effectsProposes unique solutions for ...

  1. Guide to prosthetic cardiac valves

    International Nuclear Information System (INIS)

    Morse, D.; Steiner, R.M.; Fernandez, J.

    1985-01-01

    This book contains 10 chapters. Some of the chapter titles are: The development of artificial heart valves: Introduction and historical perspective; The radiology of prosthetic heart valves; The evaluation of patients for prosthetic valve implantation; Pathology of cardiac valve replacement; and Bioengineering of mechanical and biological heart valve substitutes

  2. Photon-gated spin transistor

    OpenAIRE

    Li, Fan; Song, Cheng; Cui, Bin; Peng, Jingjing; Gu, Youdi; Wang, Guangyue; Pan, Feng

    2017-01-01

    Spin-polarized field-effect transistor (spin-FET), where a dielectric layer is generally employed for the electrical gating as the traditional FET, stands out as a seminal spintronic device under the miniaturization trend of electronics. It would be fundamentally transformative if optical gating was used for spin-FET. We report a new type of spin-polarized field-effect transistor (spin-FET) with optical gating, which is fabricated by partial exposure of the (La,Sr)MnO3 channel to light-emitti...

  3. Intelligent Flow Control Valve

    Science.gov (United States)

    Kelley, Anthony R (Inventor)

    2015-01-01

    The present invention is an intelligent flow control valve which may be inserted into the flow coming out of a pipe and activated to provide a method to stop, measure, and meter flow coming from the open or possibly broken pipe. The intelligent flow control valve may be used to stop the flow while repairs are made. Once repairs have been made, the valve may be removed or used as a control valve to meter the amount of flow from inside the pipe. With the addition of instrumentation, the valve may also be used as a variable area flow meter and flow controller programmed based upon flowing conditions. With robotic additions, the valve may be configured to crawl into a desired pipe location, anchor itself, and activate flow control or metering remotely.

  4. Nuclear valves latest development

    International Nuclear Information System (INIS)

    Isaac, F.; Monier, M.

    1993-01-01

    In the frame of Nuclear Power Plant upgrade (Emergency Power Supply and Emergency Core Cooling), Westinghouse had to face a new valve design philosophy specially for motor operated valves. The valves have to been designed to resist any operating conditions, postulated accident or loss of control. The requirements for motor operated valves are listed and the selected model and related upgrading explained. As part of plant upgrade and valves replacement, Westinghouse has sponsored alternative hardfacing research programme. Two types of materials have been investigated: nickel base alloys and iron base alloys. Programme requirements and test results are given. A new globe valve model (On-Off or regulating) is described developed by Alsthom Velan permitting the seat replacement in less than 10 min. (Z.S.) 2 figs

  5. Cryogenic Cam Butterfly Valve

    Science.gov (United States)

    McCormack, Kenneth J. (Inventor)

    2016-01-01

    A cryogenic cam butterfly valve has a body that includes an axially extending fluid conduit formed there through. A disc lug is connected to a back side of a valve disc and has a circular bore that receives and is larger than a cam of a cam shaft. The valve disc is rotatable for a quarter turn within the body about a lug axis that is offset from the shaft axis. Actuating the cam shaft in the closing rotational direction first causes the camming side of the cam of the cam shaft to rotate the disc lug and the valve disc a quarter turn from the open position to the closed position. Further actuating causes the camming side of the cam shaft to translate the valve disc into sealed contact with the valve seat. Opening rotational direction of the cam shaft reverses these motions.

  6. Spin current

    CERN Document Server

    Valenzuela, Sergio O; Saitoh, Eiji; Kimura, Takashi

    2012-01-01

    In a new branch of physics and technology called spin-electronics or spintronics, the flow of electrical charge (usual current) as well as the flow of electron spin, the so-called 'spin current', are manipulated and controlled together. This book provides an introduction and guide to the new physics and application of spin current.

  7. Enhancement of magnetoresistance by inserting thin NiAl layers at the interfaces in Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5}/Ag/Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5} current-perpendicular-to-plane pseudo spin valves

    Energy Technology Data Exchange (ETDEWEB)

    Jung, J. W.; Sakuraba, Y., E-mail: Sakuraba.Yuya@nims.go.jp; Sasaki, T. T.; Hono, K. [National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan); Miura, Y. [National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba, Ibaraki 305-0047 (Japan); Kyoto Institute of Technology, Electrical Engineering and Electronics, Kyoto 606-8585 (Japan)

    2016-03-07

    We have investigated the effects of insertion of a thin NiAl layer (≤0.63 nm) into a Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5} (CFGG)/Ag interface on the magnetoresistive properties in CFGG/Ag/CFGG current-perpendicular-to-plane giant magnetoresistance (CPP-GMR) pseudo spin valves (PSVs). First-principles calculations of ballistic transmittance clarified that the interfacial band matching at the (001)-oriented NiAl/CFGG interface is better than that at the (001)-Ag/CFGG interface. The insertion of 0.21-nm-thick NiAl layers at the Co{sub 2}FeGa{sub 0.5}Ge{sub 0.5}/Ag interfaces effectively improved the magnetoresistance (MR) output; the observed average and the highest MR ratio (ΔRA) are 62% (25 mΩ μm{sup 2}) and 77% (31 mΩ μm{sup 2}) at room temperature, respectively, which are much higher than those without NiAl insertion. Microstructural analysis using scanning transmission electron microscopy confirmed the existence of thin NiAl layers at the Ag interfaces with only modest interdiffusion even after annealing at 550 °C. The improvement of the interfacial spin-dependent scattering by very thin NiAl insertion can be a predominant reason for the enhancement of the MR output.

  8. Aortic or Mitral Valve Replacement With the Biocor and Biocor Supra

    Science.gov (United States)

    2017-04-26

    Aortic Valve Insufficiency; Aortic Valve Regurgitation; Aortic Valve Stenosis; Aortic Valve Incompetence; Mitral Valve Insufficiency; Mitral Valve Regurgitation; Mitral Valve Stenosis; Mitral Valve Incompetence

  9. Spin transport and relaxation in graphene

    International Nuclear Information System (INIS)

    Han Wei; McCreary, K.M.; Pi, K.; Wang, W.H.; Li Yan; Wen, H.; Chen, J.R.; Kawakami, R.K.

    2012-01-01

    We review our recent work on spin injection, transport and relaxation in graphene. The spin injection and transport in single layer graphene (SLG) were investigated using nonlocal magnetoresistance (MR) measurements. Spin injection was performed using either transparent contacts (Co/SLG) or tunneling contacts (Co/MgO/SLG). With tunneling contacts, the nonlocal MR was increased by a factor of ∼1000 and the spin injection/detection efficiency was greatly enhanced from ∼1% (transparent contacts) to ∼30%. Spin relaxation was investigated on graphene spin valves using nonlocal Hanle measurements. For transparent contacts, the spin lifetime was in the range of 50-100 ps. The effects of surface chemical doping showed that for spin lifetimes in the order of 100 ps, charged impurity scattering (Au) was not the dominant mechanism for spin relaxation. While using tunneling contacts to suppress the contact-induced spin relaxation, we observed the spin lifetimes as long as 771 ps at room temperature, 1.2 ns at 4 K in SLG, and 6.2 ns at 20 K in bilayer graphene (BLG). Furthermore, contrasting spin relaxation behaviors were observed in SLG and BLG. We found that Elliot-Yafet spin relaxation dominated in SLG at low temperatures whereas Dyakonov-Perel spin relaxation dominated in BLG at low temperatures. Gate tunable spin transport was studied using the SLG property of gate tunable conductivity and incorporating different types of contacts (transparent and tunneling contacts). Consistent with theoretical predictions, the nonlocal MR was proportional to the SLG conductivity for transparent contacts and varied inversely with the SLG conductivity for tunneling contacts. Finally, bipolar spin transport in SLG was studied and an electron-hole asymmetry was observed for SLG spin valves with transparent contacts, in which nonlocal MR was roughly independent of DC bias current for electrons, but varied significantly with DC bias current for holes. These results are very important for

  10. Magnetic Check Valve

    Science.gov (United States)

    Morris, Brian G.; Bozeman, Richard J., Jr.

    1994-01-01

    Poppet in proposed check valve restored to closed condition by magnetic attraction instead of spring force. Oscillations suppressed, with consequent reduction of wear. Stationary magnetic disk mounted just upstream of poppet, also containing magnet. Valve body nonmagnetic. Forward pressure or flow would push poppet away from stationary magnetic disk so fluid flows easily around poppet. Stop in valve body prevents poppet from being swept away. When flow stopped or started to reverse, magnetic attraction draws poppet back to disk. Poppet then engages floating O-ring, thereby closing valve and preventing reverse flow. Floating O-ring facilitates sealing at low loads.

  11. Butterfly valves for seawater

    International Nuclear Information System (INIS)

    Yamanaka, Katsuto

    1991-01-01

    Recently in thermal and nuclear power stations and chemical plants which have become large capacity, large quantity of cooling water is required, and mostly seawater is utilized. In these cooling water systems, considering thermal efficiency and economy, the pipings become complex, and various control functions are demanded. For the purpose, the installation of shut-off valves and control valves for pipings is necessary. The various types of valves have been employed, and in particular, butterfly valves have many merits in their function, size, structure, operation, maintenance, usable period, price and so on. The corrosion behavior of seawater is complicated due to the pollution of seawater, therefore, the environment of the valves used for seawater became severe. The structure and the features of the butterfly valves for seawater, the change of the structure of the butterfly valves for seawater and the checkup of the butterfly valves for seawater are reported. The corrosion of metallic materials is complicatedly different due to the locating condition of plants, the state of pipings and the condition of use. The corrosion countermeasures for butterfly valves must be examined from the synthetic viewpoints. (K.I.)

  12. Redo mitral valve surgery

    Directory of Open Access Journals (Sweden)

    Redoy Ranjan

    2018-03-01

    Full Text Available This study is based on the findings of a single surgeon’s practice of mitral valve replacement of 167 patients from April 2005 to June 2017 who developed symptomatic mitral restenosis after closed or open mitral commisurotomy. Both clinical and color doppler echocardiographic data of peri-operative and six months follow-up period were evaluated and compared to assess the early outcome of the redo mitral valve surgery. With male-female ratio of 1: 2.2 and after a duration of 6 to 22 years symptom free interval between the redo procedures, the selected patients with mitral valve restenosis undergone valve replacement with either mechanical valve in 62% cases and also tissue valve in 38% cases. Particular emphasis was given to separate the adhered pericardium from the heart completely to ameliorate base to apex and global contraction of the heart. Besides favorable post-operative clinical outcome, the echocardiographic findings were also encouraging as there was statistically significant increase in the mitral valve area and ejection fraction with significant decrease in the left atrial diameter, pressure gradient across the mitral valve and pulmonary artery systolic pressure. Therefore, in case of inevitable mitral restenosis after closed or open commisurotomy, mitral valve replacement is a promising treatment modality.

  13. Dynamical spin accumulation in large-spin magnetic molecules

    Science.gov (United States)

    Płomińska, Anna; Weymann, Ireneusz; Misiorny, Maciej

    2018-01-01

    The frequency-dependent transport through a nanodevice containing a large-spin magnetic molecule is studied theoretically in the Kondo regime. Specifically, the effect of magnetic anisotropy on dynamical spin accumulation is of primary interest. Such accumulation arises due to finite components of frequency-dependent conductance that are off diagonal in spin. Here, employing the Kubo formalism and the numerical renormalization group method, we demonstrate that the dynamical transport properties strongly depend on the relative orientation of spin moments in electrodes of the device, as well as on intrinsic parameters of the molecule. In particular, the effect of dynamical spin accumulation is found to be greatly affected by the type of magnetic anisotropy exhibited by the molecule, and it develops for frequencies corresponding to the Kondo temperature. For the parallel magnetic configuration of the device, the presence of dynamical spin accumulation is conditioned by the interplay of ferromagnetic-lead-induced exchange field and the Kondo correlations.

  14. Diseases of the Tricuspid Valve

    Science.gov (United States)

    ... stenosis. Tricuspid Regurgitation Tricuspid regurgitation is also called tricuspid insufficiency or tricuspid incompetence. It means there is a ... require valve surgery. Tags: heart valves , tricuspid incompetence , ... tricuspid regurgitation , tricuspid stenosis , valve disease Related Links ...

  15. Novel Magnetic Devices

    National Research Council Canada - National Science Library

    Schuller, Ivan

    2007-01-01

    ...: ballistic magnetoresistance, magnetic field proximity effect and spin drag. These three phenomena would then be exploited for the design of novel device architectures and to investigate the physical principles behind these devices...

  16. Prosthetic valve endocarditis 7 months after transcatheter aortic valve implantation diagnosed with 3D TEE

    Directory of Open Access Journals (Sweden)

    Cenk Sarı

    2016-03-01

    Full Text Available Transcatheter aortic valve implantation (TAVI was introduced as an alternative treatment for patients with severe symptomatic aortic stenosis for whom surgery would be high-risk. Prosthetic aortic valve endocarditis is a serious complication of surgical AVR (SAVR with high morbidity and mortality. According to recent cases, post-TAVI prosthetic valve endocarditis (PVE seems to occur very rarely. We present the case of a 75-year-old woman who underwent TAVI (Edwards Saphien XT with an uneventful postoperative stay. She was diagnosed with endocarditis using three dimensional (3D echocardiography on the TAVI device 7 months later and she subsequently underwent surgical aortic valve replacement. Little experience of the interpretation of transoesophageal echocardiography (TEE and the clinical course and effectiveness of treatment strategies in post-TAVI endocarditis exists. We report a case of PVE in a TAVI patient which was diagnosed with three-dimensional transoesophageal echocardiography (3DTEE.

  17. Efficacy and safety of the Lotus Valve System for treatment of patients with severe aortic valve stenosis and intermediate surgical risk

    DEFF Research Database (Denmark)

    De Backer, Ole; Götberg, Matthias; Ihlberg, Leo

    2016-01-01

    increasingly used to treat patients with an intermediate risk profile. METHODS AND RESULTS: The study was designed as an independent Nordic multicenter registry of intermediate risk patients treated with the Lotus Valve System (Boston Scientific, MA, USA; N=154). Valve Academic Research Consortium (VARC......)-defined device success was obtained in 97.4%. A Lotus Valve was successfully implanted in all patients. There was no valve migration, embolization, ectopic valve deployment, or TAV-in-TAV deployment. The VARC-defined combined safety rate at 30days was 92.2%, with a mortality rate of 1.9% and stroke rate of 3...

  18. Geometrical spin symmetry and spin

    International Nuclear Information System (INIS)

    Pestov, I. B.

    2011-01-01

    Unification of General Theory of Relativity and Quantum Mechanics leads to General Quantum Mechanics which includes into itself spindynamics as a theory of spin phenomena. The key concepts of spindynamics are geometrical spin symmetry and the spin field (space of defining representation of spin symmetry). The essence of spin is the bipolar structure of geometrical spin symmetry induced by the gravitational potential. The bipolar structure provides a natural derivation of the equations of spindynamics. Spindynamics involves all phenomena connected with spin and provides new understanding of the strong interaction.

  19. Stent fracture, valve dysfunction, and right ventricular outflow tract reintervention after transcatheter pulmonary valve implantation: patient-related and procedural risk factors in the US Melody Valve Trial.

    Science.gov (United States)

    McElhinney, Doff B; Cheatham, John P; Jones, Thomas K; Lock, James E; Vincent, Julie A; Zahn, Evan M; Hellenbrand, William E

    2011-12-01

    Among patients undergoing transcatheter pulmonary valve (TPV) replacement with the Melody valve, risk factors for Melody stent fracture (MSF) and right ventricular outflow tract (RVOT) reintervention have not been well defined. From January 2007 to January 2010, 150 patients (median age, 19 years) underwent TPV implantation in the Melody valve Investigational Device Exemption trial. Existing conduit stents from a prior catheterization were present in 37 patients (25%, fractured in 12); 1 or more new prestents were placed at the TPV implant catheterization in 51 patients. During follow-up (median, 30 months), MSF was diagnosed in 39 patients. Freedom from a diagnosis of MSF was 77±4% at 14 months (after the 1-year evaluation window) and 60±9% at 39 months (3-year window). On multivariable analysis, implant within an existing stent, new prestent, or bioprosthetic valve (combined variable) was associated with longer freedom from MSF (Pbioprosthetic valve was associated with lower risk of MSF and reintervention.

  20. Excitation of coherent propagating spin waves by pure spin currents.

    Science.gov (United States)

    Demidov, Vladislav E; Urazhdin, Sergei; Liu, Ronghua; Divinskiy, Boris; Telegin, Andrey; Demokritov, Sergej O

    2016-01-28

    Utilization of pure spin currents not accompanied by the flow of electrical charge provides unprecedented opportunities for the emerging technologies based on the electron's spin degree of freedom, such as spintronics and magnonics. It was recently shown that pure spin currents can be used to excite coherent magnetization dynamics in magnetic nanostructures. However, because of the intrinsic nonlinear self-localization effects, magnetic auto-oscillations in the demonstrated devices were spatially confined, preventing their applications as sources of propagating spin waves in magnonic circuits using these waves as signal carriers. Here, we experimentally demonstrate efficient excitation and directional propagation of coherent spin waves generated by pure spin current. We show that this can be achieved by using the nonlocal spin injection mechanism, which enables flexible design of magnetic nanosystems and allows one to efficiently control their dynamic characteristics.

  1. Acceptance and introduction of disruptive technologies - simple steps to build a fully functional pulmonary valved stent.

    Science.gov (United States)

    Huber, Christoph H; Marty, Bettina; von Segesser, Ludwig K

    2007-08-01

    Valved stents are new land for cardiac surgeons even though they are being used more frequently by interventional disciplines. This paper presents simple steps to build a patient-specific pulmonary valved stent and its delivery device. The design concept was tested by random participants at a med-tech meeting. The valved stent is constructed by linking an endoprosthetic graft with a valved-jugular-vein. The delivery device is made from a modified 5-ml syringe. Of 72 participants, 66 (92%) built and 60 participants implanted the device successfully into the targeted pulmonary position via a trans-infundibular access.

  2. Danfos: Thermostatic Radiator Valves

    DEFF Research Database (Denmark)

    Gregersen, Niels; Oliver, James; Hjorth, Poul G.

    2000-01-01

    This problem deals with modelling the flow through a typical Danfoss thermostatic radiator valve.Danfoss is able to employ Computational Fluid Dynamics (CFD) in calculations of the capacity of valves, but an experienced engineer can often by rules of thumb "guess" the capacity, with a precision...

  3. Spin-inversion in nanoscale graphene sheets with a Rashba spin-orbit barrier

    Directory of Open Access Journals (Sweden)

    Somaieh Ahmadi

    2012-03-01

    Full Text Available Spin-inversion properties of an electron in nanoscale graphene sheets with a Rashba spin-orbit barrier is studied using transfer matrix method. It is found that for proper values of Rashba spin-orbit strength, perfect spin-inversion can occur in a wide range of electron incident angle near the normal incident. In this case, the graphene sheet with Rashba spin-orbit barrier can be considered as an electron spin-inverter. The efficiency of spin-inverter can increase up to a very high value by increasing the length of Rashba spin-orbit barrier. The effect of intrinsic spin-orbit interaction on electron spin inversion is then studied. It is shown that the efficiency of spin-inverter decreases slightly in the presence of intrinsic spin-orbit interaction. The present study can be used to design graphene-based spintronic devices.

  4. Spin injection into GaAs

    Energy Technology Data Exchange (ETDEWEB)

    Endres, Bernhard

    2013-11-01

    In this work spin injection into GaAs from Fe and (Ga,Mn)As was investigated. For the realization of any spintronic device the detailed knowledge about the spin lifetime, the spatial distribution of spin-polarized carriers and the influence of electric fields is essential. In the present work all these aspects have been analyzed by optical measurements of the polar magneto-optic Kerr effect (pMOKE) at the cleaved edge of the samples. Besides the attempt to observe spin pumping and thermal spin injection into n-GaAs the spin solar cell effect is demonstrated, a novel mechanism for the optical generation of spins in semiconductors with potential for future spintronic applications. Also important for spin-based devices as transistors is the presented realization of electrical spin injection into a two-dimensional electron gas.

  5. Spin Injection in Indium Arsenide

    Directory of Open Access Journals (Sweden)

    Mark eJohnson

    2015-08-01

    Full Text Available In a two dimensional electron system (2DES, coherent spin precession of a ballistic spin polarized current, controlled by the Rashba spin orbit interaction, is a remarkable phenomenon that’s been observed only recently. Datta and Das predicted this precession would manifest as an oscillation in the source-drain conductance of the channel in a spin-injected field effect transistor (Spin FET. The indium arsenide single quantum well materials system has proven to be ideal for experimental confirmation. The 2DES carriers have high mobility, low sheet resistance, and high spin orbit interaction. Techniques for electrical injection and detection of spin polarized carriers were developed over the last two decades. Adapting the proposed Spin FET to the Johnson-Silsbee nonlocal geometry was a key to the first experimental demonstration of gate voltage controlled coherent spin precession. More recently, a new technique measured the oscillation as a function of channel length. This article gives an overview of the experimental phenomenology of the spin injection technique. We then review details of the application of the technique to InAs single quantum well (SQW devices. The effective magnetic field associated with Rashba spin-orbit coupling is described, and a heuristic model of coherent spin precession is presented. The two successful empirical demonstrations of the Datta Das conductance oscillation are then described and discussed.

  6. Spin Transport in Semiconductor heterostructures

    International Nuclear Information System (INIS)

    Marinescu, Domnita Catalina

    2011-01-01

    The focus of the research performed under this grant has been the investigation of spin transport in magnetic semiconductor heterostructures. The interest in these systems is motivated both by their intriguing physical properties, as the physical embodiment of a spin-polarized Fermi liquid, as well as by their potential applications as spintronics devices. In our work we have analyzed several different problems that affect the spin dynamics in single and bi-layer spin-polarized two-dimensional (2D) systems. The topics of interests ranged from the fundamental aspects of the electron-electron interactions, to collective spin and charge density excitations and spin transport in the presence of the spin-orbit coupling. The common denominator of these subjects is the impact at the macroscopic scale of the spin-dependent electron-electron interaction, which plays a much more subtle role than in unpolarized electron systems. Our calculations of several measurable parameters, such as the excitation frequencies of magneto-plasma modes, the spin mass, and the spin transresistivity, propose realistic theoretical estimates of the opposite-spin many-body effects, in particular opposite-spin correlations, that can be directly connected with experimental measurements.

  7. Bioprinting a cardiac valve.

    Science.gov (United States)

    Jana, Soumen; Lerman, Amir

    2015-12-01

    Heart valve tissue engineering could be a possible solution for the limitations of mechanical and biological prostheses, which are commonly used for heart valve replacement. In tissue engineering, cells are seeded into a 3-dimensional platform, termed the scaffold, to make the engineered tissue construct. However, mimicking the mechanical and spatial heterogeneity of a heart valve structure in a fabricated scaffold with uniform cell distribution is daunting when approached conventionally. Bioprinting is an emerging technique that can produce biological products containing matrix and cells, together or separately with morphological, structural and mechanical diversity. This advance increases the possibility of fabricating the structure of a heart valve in vitro and using it as a functional tissue construct for implantation. This review describes the use of bioprinting technology in heart valve tissue engineering. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Space Vehicle Valve System

    Science.gov (United States)

    Kelley, Anthony R. (Inventor); Lindner, Jeffrey L. (Inventor)

    2014-01-01

    The present invention is a space vehicle valve system which controls the internal pressure of a space vehicle and the flow rate of purged gases at a given internal pressure and aperture site. A plurality of quasi-unique variable dimension peaked valve structures cover the purge apertures on a space vehicle. Interchangeable sheet guards configured to cover valve apertures on the peaked valve structure contain a pressure-activated surface on the inner surface. Sheet guards move outwardly from the peaked valve structure when in structural contact with a purge gas stream flowing through the apertures on the space vehicle. Changing the properties of the sheet guards changes the response of the sheet guards at a given internal pressure, providing control of the flow rate at a given aperture site.

  9. Multiple-port valve

    International Nuclear Information System (INIS)

    Doody, T.J.

    1978-01-01

    A multiple-port valve assembly is designed to direct flow from a primary conduit into any one of a plurality of secondary conduits as well as to direct a reverse flow. The valve includes two mating hemispherical sockets that rotatably receive a spherical valve plug. The valve plug is attached to the primary conduit and includes diverging passageways from that conduit to a plurality of ports. Each of the ports is alignable with one or more of a plurality of secondary conduits fitting into one of the hemispherical sockets. The other hemispherical socket includes a slot for the primary conduit such that the conduit's motion along that slot with rotation of the spherical plug about various axes will position the valve-plug ports in respect to the secondary conduits

  10. Automated control of the laser welding process of heart valve scaffolds

    Directory of Open Access Journals (Sweden)

    Weber Moritz

    2016-09-01

    Full Text Available Using the electrospinning process the geometry of a heart valve is not replicable by just one manufacturing process. To produce heart valve scaffolds the heart valve leaflets and the vessel have to be produced in separated spinning processes. For the final product of a heart valve they have to be mated afterwards. In this work an already existing three-axes laser was enhanced to laser weld those scaffolds. The automation control software is based on the robot operating system (ROS. The mechatronically control is done by an Arduino Mega. A graphical user interface (GUI is written with Python and Kivy.

  11. Main feedwater valve diagnostics at Waterford 3 nuclear generating station

    International Nuclear Information System (INIS)

    Fitzgerald, W.V.

    1991-01-01

    Pneumatically-operated control valves are coming under increasing scrutiny in nuclear power plants because of their relatively high incident rate. The theory behind a device that could make performance evaluation of these valves simpler and more effective was first described at the original EPRI Power Plant Valve Symposium. The development of this Diagnostic System was completed in 1989, and it was recently used to troubleshoot two main feedwater valves at Louisiana Power and Light's Waterford 3 Power Station. During a cold snap last December, these valves failed to respond to the input signal and, as a result, the plant came off line. An incident report had to be filed, and the plant chose to contact the original equipment manufacturer (OEM) for assistance. This paper describes the original incident involving these valves and then gives a brief description of the diagnostic system and how it works. The balance of the paper then reviews how the OEM and plant personnel utilized the system to evaluate each component of the control valve assembly (I/P transducer, positioner, volume boosters, actuator, and valve body assembly). By simply stroking the valve and monitoring pneumatic signals and valve position, the problem was traced to a malfunctioning positioner and a volume booster that was leaking. The problems were corrected and new performance signatures run for the valves using the system to document their improved operation. This case study demonstrates how new Diagnostic Technology along with OEM involvement can effectively address problems with pneumatically-operated control valves so that root-cause solutions can be implemented

  12. Next generation spin torque memories

    CERN Document Server

    Kaushik, Brajesh Kumar; Kulkarni, Anant Aravind; Prajapati, Sanjay

    2017-01-01

    This book offers detailed insights into spin transfer torque (STT) based devices, circuits and memories. Starting with the basic concepts and device physics, it then addresses advanced STT applications and discusses the outlook for this cutting-edge technology. It also describes the architectures, performance parameters, fabrication, and the prospects of STT based devices. Further, moving from the device to the system perspective it presents a non-volatile computing architecture composed of STT based magneto-resistive and all-spin logic devices and demonstrates that efficient STT based magneto-resistive and all-spin logic devices can turn the dream of instant on/off non-volatile computing into reality.

  13. Compact UHV valve with field replaceable windows

    International Nuclear Information System (INIS)

    Johnson, E.D.; Freeman, J.; Powell, F.

    1991-01-01

    There are many applications in synchrotron radiation research where window valves can be usefully employed. Examples include gas cells for monochromator calibration, filters for high order light rejection, and as vacuum isolation elements between machine and experimental vacua. Often these devices are fairly expensive, and have only fixed (ie non-removable) windows. The development of a new type of seal technology by VAT for their series 01 valves provides a gate surface which is free from obstructions due to internal mechanical elements. This feature allows a threaded recess to be machined into the gate to receive a removable window frame which can carry standard size Luxel thin film windows. The combination of these features results in a DN 40 (2.75in. conflat flange) valve which provides a clear aperture of 21mm diameter for the window material. 8 refs., 2 figs

  14. Spin-dependent transport and current-induced spin transfer torque in a disordered zigzag silicene nanoribbon

    International Nuclear Information System (INIS)

    Zhou, Benliang; Zhou, Benhu; Liu, Guang; Guo, Dan; Zhou, Guanghui

    2016-01-01

    We study theoretically the spin-dependent transport and the current-induced spin transfer torque (STT) for a zigzag silicene nanoribbon (ZSiNR) with Anderson-type disorders between two ferromagnetic electrodes. By using the nonequilibrium Green's function method, it is predicted that the transport property and STT through the junction depend sensitively on the disorder, especially around the Dirac point. As a result, the conductance decreases and increases for two electrode in parallel and antiparallel configurations, respectively. Due to the disorder, the magnetoresistance (MR) decreases accordingly even within the energy regime for the perfect plateau without disorders. In addition, the conductance versus the relative angle of the magnetization shows a cosine-like behavior. The STT per unit of the bias voltage versus the angle of the magnetization exhibits a sine-like behavior, and versus the Fermi energy is antisymmetrical to the Dirac point and exhibits sharp peaks. Furthermore, the peaks of the STT are suppressed much as the disorder strength increases, especially around the Dirac point. The results obtained here may provide a valuable suggestion to experimentally design spin valve devices based on ZSiNR.

  15. Spin-dependent transport and current-induced spin transfer torque in a disordered zigzag silicene nanoribbon

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Benliang [Department of Physics and Key Laboratory for Low-Dimensional Quantum Structures and Manipulation (Ministry of Education), Synergetic Innovation Center for Quantum Effects and Applications of Hunan, Hunan Normal University, Changsha 410081 (China); Zhou, Benhu [Department of Physics, Shaoyang University, Shaoyang 422001 (China); Liu, Guang; Guo, Dan [Department of Physics and Key Laboratory for Low-Dimensional Quantum Structures and Manipulation (Ministry of Education), Synergetic Innovation Center for Quantum Effects and Applications of Hunan, Hunan Normal University, Changsha 410081 (China); Zhou, Guanghui, E-mail: ghzhou@hunnu.edu.cn [Department of Physics and Key Laboratory for Low-Dimensional Quantum Structures and Manipulation (Ministry of Education), Synergetic Innovation Center for Quantum Effects and Applications of Hunan, Hunan Normal University, Changsha 410081 (China)

    2016-11-01

    We study theoretically the spin-dependent transport and the current-induced spin transfer torque (STT) for a zigzag silicene nanoribbon (ZSiNR) with Anderson-type disorders between two ferromagnetic electrodes. By using the nonequilibrium Green's function method, it is predicted that the transport property and STT through the junction depend sensitively on the disorder, especially around the Dirac point. As a result, the conductance decreases and increases for two electrode in parallel and antiparallel configurations, respectively. Due to the disorder, the magnetoresistance (MR) decreases accordingly even within the energy regime for the perfect plateau without disorders. In addition, the conductance versus the relative angle of the magnetization shows a cosine-like behavior. The STT per unit of the bias voltage versus the angle of the magnetization exhibits a sine-like behavior, and versus the Fermi energy is antisymmetrical to the Dirac point and exhibits sharp peaks. Furthermore, the peaks of the STT are suppressed much as the disorder strength increases, especially around the Dirac point. The results obtained here may provide a valuable suggestion to experimentally design spin valve devices based on ZSiNR.

  16. Nuclear spins in nanostructures

    International Nuclear Information System (INIS)

    Coish, W.A.; Baugh, J.

    2009-01-01

    We review recent theoretical and experimental advances toward understanding the effects of nuclear spins in confined nanostructures. These systems, which include quantum dots, defect centers, and molecular magnets, are particularly interesting for their importance in quantum information processing devices, which aim to coherently manipulate single electron spins with high precision. On one hand, interactions between confined electron spins and a nuclear-spin environment provide a decoherence source for the electron, and on the other, a strong effective magnetic field that can be used to execute local coherent rotations. A great deal of effort has been directed toward understanding the details of the relevant decoherence processes and to find new methods to manipulate the coupled electron-nuclear system. A sequence of spectacular new results have provided understanding of spin-bath decoherence, nuclear spin diffusion, and preparation of the nuclear state through dynamic polarization and more general manipulation of the nuclear-spin density matrix through ''state narrowing.'' These results demonstrate the richness of this physical system and promise many new mysteries for the future. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  17. Gate valve performance prediction

    International Nuclear Information System (INIS)

    Harrison, D.H.; Damerell, P.S.; Wang, J.K.; Kalsi, M.S.; Wolfe, K.J.

    1994-01-01

    The Electric Power Research Institute is carrying out a program to improve the performance prediction methods for motor-operated valves. As part of this program, an analytical method to predict the stem thrust required to stroke a gate valve has been developed and has been assessed against data from gate valve tests. The method accounts for the loads applied to the disc by fluid flow and for the detailed mechanical interaction of the stem, disc, guides, and seats. To support development of the method, two separate-effects test programs were carried out. One test program determined friction coefficients for contacts between gate valve parts by using material specimens in controlled environments. The other test program investigated the interaction of the stem, disc, guides, and seat using a special fixture with full-sized gate valve parts. The method has been assessed against flow-loop and in-plant test data. These tests include valve sizes from 3 to 18 in. and cover a considerable range of flow, temperature, and differential pressure. Stem thrust predictions for the method bound measured results. In some cases, the bounding predictions are substantially higher than the stem loads required for valve operation, as a result of the bounding nature of the friction coefficients in the method

  18. Modeling valve leakage

    International Nuclear Information System (INIS)

    Bell, S.R.; Rohrscheib, R.

    1994-01-01

    The American Society of Mechanical Engineers (ASME) Code requires individual valve leakage testing for Category A valves. Although the U.S. Nuclear Regulatory Commission (USNRC) has recognized that it is more appropriate to test containment isolation valves in groups, as allowed by 10 CFR 50, Appendix J, a utility seeking relief from these Code requirements must provide technical justification for the relief and establish a conservative alternate acceptance criteria. In order to provide technical justification for group testing of containment isolation valves, Illinois Power developed a calculation (model) for determining the size of a leakage pathway in a valve disc or seat for a given leakage rate. The model was verified experimentally by machining leakage pathways of known size and then measuring the leakage and comparing this value to the calculated value. For the range of values typical of leakage rate testing, the correlation between the experimental values and calculated values was quote good. Based upon these results, Illinois Power established a conservative acceptance criteria for all valves in the inservice testing (IST) program and was granted relief by the USNRC from the individual leakage testing requirements of the ASME Code. This paper presents the results of Illinois Power's work in the area of valve leakage rate testing

  19. Semiconductors put spin in spintronics

    International Nuclear Information System (INIS)

    Weiss, Dieter

    2000-01-01

    Electrons and holes, which carry the current in semiconductor devices, are quantum-mechanical objects characterized by a set of quantum numbers - the band index, the wave-vector (which is closely related to the electron or hole velocity) and spin. The spin, however, is one of the strangest properties of particles. In simple terms, we can think of the spin as an internal rotation of the electron, but it has no classical counterpart. The spin is connected to a quantized magnetic moment and hence acts as a microscopic magnet. Thus the electron spin can adopt one of two directions (''up'' or ''down'') in a magnetic field. The spin plays no role in conventional electronics and the current in any semiconductor device is made up of a mixture of electrons with randomly oriented spins. However, a new range of electronic devices that transport the spin of the electrons, in addition to their charge, is being developed. But the biggest obstacle to making practical ''spin electronic'' or ''spintronic'' devices so far has been finding a way of injecting spin-polarized electrons or holes into the semiconductor and then detecting them. Recently a team of physicists from the University of Wuerzburg in Germany, and also a collaboration of researchers from Tohoku University in Japan and the University of California at Santa Barbara, have found a way round these problems using either semi-magnetic or ferromagnetic semiconductors as ''spin aligners'' (R Fiederling et al. 1999 Nature 402 787; Y Ohno et al. 1999 Nature 402 790). In this article the author presents the latest breakthrough in spintronics research. (UK)

  20. Face-Sealing Butterfly Valve

    Science.gov (United States)

    Tervo, John N.

    1992-01-01

    Valve plate made to translate as well as rotate. Valve opened and closed by turning shaft and lever. Interactions among lever, spring, valve plate, and face seal cause plate to undergo combination of translation and rotation so valve plate clears seal during parts of opening and closing motions.

  1. Fabrication of micro metallic valve and pump

    Science.gov (United States)

    Yang, Ming; Kabasawa, Yasunari; Ito, Kuniyoshi

    2010-03-01

    Fabrication of micro devices by using micro metal forming was proposed by the authors. We developed a desktop servo-press machine with precise tooling system. Precise press forming processes including micro forging and micro joining has been carried out in a progressive die. In this study, micro metallic valve and pump were fabricated by using the precise press forming. The components are made of sheet metals, and assembled in to a unit in the progressive die. A micro check-valve with a diameter of 3mm and a length of 3.2mm was fabricated, and the property of flow resistance was evaluated. The results show that the check valve has high property of leakage proof. Since the valve is a unit parts with dimensions of several millimeters, it has advantage to be adapted to various pump design. Here, two kinds of micro pumps with the check-valves were fabricated. One is diaphragm pump actuated by vibration of the diaphragm, and another is tube-shaped pump actuated by resonation. The flow quantities of the pumps were evaluated and the results show that both of the pumps have high pumping performance.

  2. Low intrinsic carrier density LSMO/Alq3/AlOx/Co organic spintronic devices

    Science.gov (United States)

    Riminucci, Alberto; Graziosi, Patrizio; Calbucci, Marco; Cecchini, Raimondo; Prezioso, Mirko; Borgatti, Francesco; Bergenti, Ilaria; Dediu, Valentin Alek

    2018-04-01

    The understanding of spin injection and transport in organic spintronic devices is still incomplete, with some experiments showing magnetoresistance and others not detecting it. We have investigated the transport properties of a large number of tris-(8-hydroxyquinoline)aluminum-based organic spintronic devices with an electrical resistance greater than 5 MΩ that did not show magnetoresistance. Their transport properties could be described satisfactorily by known models for organic semiconductors. At high voltages (>2 V), the results followed the model of space charge limited current with a Poole-Frenkel mobility. At low voltages (˜0.1 V), that are those at which the spin valve behavior is usually observed, the charge transport was modelled by nearest neighbor hopping in intra-gap impurity levels, with a charge carrier density of n0 = (1.44 ± 0.21) × 1015 cm-3 at room temperature. Such a low carrier density can explain why no magnetoresistance was observed.

  3. Magnetic proximity control of spin currents and giant spin accumulation in graphene

    Science.gov (United States)

    Singh, Simranjeet

    Two dimensional (2D) materials provide a unique platform to explore the full potential of magnetic proximity driven phenomena. We will present the experimental study showing the strong modulation of spin currents in graphene layers by controlling the direction of the exchange field due to the ferromagnetic-insulator (FMI) magnetization in graphene/FMI heterostructures. Owing to clean interfaces, a strong magnetic exchange coupling leads to the experimental observation of complete spin modulation at low externally applied magnetic fields in short graphene channels. We also discover that the graphene spin current can be fully dephased by randomly fluctuating exchange fields. This is manifested as an unusually strong temperature dependence of the non-local spin signals in graphene, which is due to spin relaxation by thermally-induced transverse fluctuations of the FMI magnetization. Additionally, it has been a challenge to grow a smooth, robust and pin-hole free tunnel barriers on graphene, which can withstand large current densities for efficient electrical spin injection. We have experimentally demonstrated giant spin accumulation in graphene lateral spin valves employing SrO tunnel barriers. Nonlocal spin signals, as large as 2 mV, are observed in graphene lateral spin valves at room temperature. This high spin accumulations observed using SrO tunnel barriers puts graphene on the roadmap for exploring the possibility of achieving a non-local magnetization switching due to the spin torque from electrically injected spins. Financial support from ONR (No. N00014-14-1-0350), NSF (No. DMR-1310661), and C-SPIN, one of the six SRC STARnet Centers, sponsored by MARCO and DARPA.

  4. GIANT PROSTHETIC VALVE THROMBUS

    Directory of Open Access Journals (Sweden)

    Prashanth Kumar

    2015-04-01

    Full Text Available Mechanical prosthetic valves are predisposed to bleeding, thrombosis & thromboembolic complications. Overall incidence of thromboembolic complications is 1% per year who are on oral anticoagulants, whereas bleeding complications incidence is 0.5% to 6.6% per year. 1, 2 Minimization of Scylla of thromboembolic & Charybdis of bleeding complication needs a balancing act of optimal antithrombotic therapy. We are reporting a case of middle aged male patient with prosthetic mitral valve presenting in heart failure. Patient had discontinued anticoagulants, as he had subdural hematoma in the past. He presented to our institute with a giant prosthetic valve thrombus.

  5. Fiber heart valve prosthesis: influence of the fabric construction parameters on the valve fatigue performances.

    Science.gov (United States)

    Vaesken, Antoine; Heim, Frederic; Chakfe, Nabil

    2014-12-01

    Transcatheter aortic valve replacement (TAVR) has become today a largely considered alternative technique to surgical valve replacement in patients who are not operable or patients with high risk for open chest surgery. However, the biological valve tissue used in the devices implanted clinically appears to be fragile material when folded for low diameter catheter insertion purpose and released in calcified environment with irregular geometry. Textile polyester material is characterized by outstanding folding and strength properties combined with proven biocompatibility. It could thereof be considered to replace biological valve leaflets in the TAVR procedure. The textile construction parameters must however be tuned to obtain a material compatible with the valve requested durability. In that context, one issue to be addressed is the friction effect that occurs between filaments and between yarns within a fabric under flexure loading. This phenomenon could be critical for the resistance of the material on the long term. The purpose of the present work is to assess the fatigue performances of textile valve prototypes made from different fabric constructions (monofilament, multifilament, calendered mutifilament) under accelerated cyclic loading. The goal is to identify, which construction is the best suited to long term fatigue stress. Results show that calendered multifilament and monofilament fabric constructions undergo strong ruptures already from 40 Mio cycles, while non calendered multifilament appears more durable. The rupture patterns observed point out that durability is directly related to the flexure stiffness level of the fibrous elements in the construction. Copyright © 2014 Elsevier Ltd. All rights reserved.

  6. System for remotely servicing a top loading captive ball valve

    International Nuclear Information System (INIS)

    Berry, S.M.; Porter, M.L.

    1996-01-01

    An attachment for facilitating servicing of a valve is disclosed including: an assembly composed of a valve seat defining a flow path, a flow control member movable relative to the valve seat for blocking or unblocking the valve seat, and a control device including a stem coupled to the flow control member and operable for moving the flow control member relative to the valve se housing for receiving the assembly, the housing having an opening via which the assembly can be removed from, and installed in, the housing, and the housing having a plurality of threaded studs which surround the opening and project away from the housing; a valve housing cover for closing and sealing the opening in the housing, the cover having a first bore for passage of the stem of the control device when the assembly is installed in the housing and a plurality of second bores each located for passage of a respective stud when the cover closes the opening in the housing. A plurality of threaded nuts are engageable with the studs for securing the cover to the housing when the cover closes the opening in the housing, wherein the attachment comprises: a plurality of nut guide devices removable from the housing and each operatively associated with a respective stud for retaining a respective nut and guiding the respective nut into alignment with the respective stud to enable the respective nut to be rotated into engagement with the respective stud; and aligning the nut guide devices with the studs. 7 figs

  7. Quantum spin transport in semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Schindler, Christoph

    2012-05-15

    In this work, we study and quantitatively predict the quantum spin Hall effect, the spin-orbit interaction induced intrinsic spin-Hall effect, spin-orbit induced magnetizations, and spin-polarized electric currents in nanostructured two-dimensional electron or hole gases with and without the presence of magnetic fields. We propose concrete device geometries for the generation, detection, and manipulation of spin polarization and spin-polarized currents. To this end a novel multi-band quantum transport theory, that we termed the multi-scattering Buettiker probe model, is developed. The method treats quantum interference and coherence in open quantum devices on the same footing as incoherent scattering and incorporates inhomogeneous magnetic fields in a gauge-invariant and nonperturbative manner. The spin-orbit interaction parameters that control effects such as band energy spin splittings, g-factors, and spin relaxations are calculated microscopically in terms of an atomistic relativistic tight-binding model. We calculate the transverse electron focusing in external magnetic and electric fields. We have performed detailed studies of the intrinsic spin-Hall effect and its inverse effect in various material systems and geometries. We find a geometry dependent threshold value for the spin-orbit interaction for the inverse intrinsic spin-Hall effect that cannot be met by n-type GaAs structures. We propose geometries that spin polarize electric current in zero magnetic field and analyze the out-of-plane spin polarization by all electrical means. We predict unexpectedly large spin-orbit induced spin-polarization effects in zero magnetic fields that are caused by resonant enhancements of the spin-orbit interaction in specially band engineered and geometrically designed p-type nanostructures. We propose a concrete realization of a spin transistor in HgTe quantum wells, that employs the helical edge channel in the quantum spin Hall effect.

  8. Quantum spin transport in semiconductor nanostructures

    International Nuclear Information System (INIS)

    Schindler, Christoph

    2012-01-01

    In this work, we study and quantitatively predict the quantum spin Hall effect, the spin-orbit interaction induced intrinsic spin-Hall effect, spin-orbit induced magnetizations, and spin-polarized electric currents in nanostructured two-dimensional electron or hole gases with and without the presence of magnetic fields. We propose concrete device geometries for the generation, detection, and manipulation of spin polarization and spin-polarized currents. To this end a novel multi-band quantum transport theory, that we termed the multi-scattering Buettiker probe model, is developed. The method treats quantum interference and coherence in open quantum devices on the same footing as incoherent scattering and incorporates inhomogeneous magnetic fields in a gauge-invariant and nonperturbative manner. The spin-orbit interaction parameters that control effects such as band energy spin splittings, g-factors, and spin relaxations are calculated microscopically in terms of an atomistic relativistic tight-binding model. We calculate the transverse electron focusing in external magnetic and electric fields. We have performed detailed studies of the intrinsic spin-Hall effect and its inverse effect in various material systems and geometries. We find a geometry dependent threshold value for the spin-orbit interaction for the inverse intrinsic spin-Hall effect that cannot be met by n-type GaAs structures. We propose geometries that spin polarize electric current in zero magnetic field and analyze the out-of-plane spin polarization by all electrical means. We predict unexpectedly large spin-orbit induced spin-polarization effects in zero magnetic fields that are caused by resonant enhancements of the spin-orbit interaction in specially band engineered and geometrically designed p-type nanostructures. We propose a concrete realization of a spin transistor in HgTe quantum wells, that employs the helical edge channel in the quantum spin Hall effect.

  9. Bioprosthetic Valve Fracture to Facilitate Transcatheter Valve-in-Valve Implantation.

    Science.gov (United States)

    Allen, Keith B; Chhatriwalla, Adnan K; Cohen, David J; Saxon, John T; Aggarwal, Sanjeev; Hart, Anthony; Baron, Suzanne; Davis, J Russell; Pak, Alex F; Dvir, Danny; Borkon, A Michael

    2017-11-01

    Valve-in-valve transcatheter aortic valve replacement is less effective in small surgical bioprostheses. We evaluated the feasibility of bioprosthetic valve fracture with a high-pressure balloon to facilitate valve-in-valve transcatheter aortic valve replacement. In vitro bench testing on aortic tissue valves was performed on 19-mm and 21-mm Mitroflow (Sorin, Milan, Italy), Magna and Magna Ease (Edwards Lifesciences, Irvine, CA), Trifecta and Biocor Epic (St. Jude Medical, Minneapolis, MN), and Hancock II and Mosaic (Medtronic, Minneapolis, MN). High-pressure balloons Tru Dilation, Atlas Gold, and Dorado (C.R. Bard, Murray Hill, NJ) were used to determine which valves could be fractured and at what pressure fracture occurred. Mitroflow, Magna, Magna Ease, Mosaic, and Biocor Epic surgical valves were successfully fractured using high-pressures balloon 1 mm larger than the labeled valve size whereas Trifecta and Hancock II surgical valves could not be fractured. Only the internal valve frame was fractured, and the sewing cuff was never disrupted. Manufacturer's rated burst pressures for balloons were exceeded, with fracture pressures ranging from 8 to 24 atmospheres depending on the surgical valve. Testing further demonstrated that fracture facilitated the expansion of previously constrained, underexpanded transcatheter valves (both balloon and self-expanding) to the manufacturer's recommended size. Bench testing demonstrates that the frame of most, but not all, bioprosthetic surgical aortic valves can be fractured using high-pressure balloons. The safety of bioprosthetic valve fracture to optimize valve-in-valve transcatheter aortic valve replacement in small surgical valves requires further clinical investigation. Copyright © 2017 The Society of Thoracic Surgeons. Published by Elsevier Inc. All rights reserved.

  10. Pulmonary valve stenosis

    Science.gov (United States)

    ... surgery - discharge Images Heart valves References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman's Cecil ... Saunders; 2016:chap 69. Otto CM, Bownow RO. Valvular heart disease. In: Mann DL, Zipes DP, Libby P, Bonow ...

  11. Mitral valve regurgitation

    Science.gov (United States)

    ... and dentist if you have a history of heart valve disease or congenital heart disease before treatment. Some people ... the middle Heart, front view References Carabello BA. Valvular heart disease. In: Goldman L, Schafer AI, eds. Goldman-Cecil ...

  12. Aortic Valve Disease

    Science.gov (United States)

    ... team will discuss with you the advantages and disadvantages of both valve types. Regardless of which type ... Diagnosis and Treatment Options Recovery Questions for Your Doctor Will my condition ever get better without treatment? ...

  13. Dry product valve

    International Nuclear Information System (INIS)

    Greaves, James D.

    1984-01-01

    This invention provides a system for delivering particulate radioactive or other toxic wastes to a container in which they can be solidified. The system includes a set of valves that prevent the escape of dusty materials to the atmosphere

  14. Ball check valve

    International Nuclear Information System (INIS)

    Bevilacqua, F.

    1978-01-01

    A pressurized nuclear reactor having an instrument assembly sheathed in a metallic tube which is extended vertically upward into the reactor core by traversing a metallic guide tube which is welded to the wall of the vessel is described. Sensors in each instrument assembly are connected to instruments outside the vessel to manifest the conditions within the core. Each instrument assembly probe is moved into position within a metallic guide channel. The guide channel penetrates the wall of the vessel and forms part of the barrier to the environment within the pressure vessel. Each channel includes a ball check valve which is opened by the instrument assembly probe when the probe passes through the valve. A ball valve element is moved from its seat by the probe to a position lateral of the bore of the channel and is guided to its seat along a sloped path within the valve body when the probe is removed. 5 claims, 3 figures

  15. Experimental Realization of a Quantum Spin Pump

    DEFF Research Database (Denmark)

    Watson, Susan; Potok, R.; M. Marcus, C.

    2003-01-01

    We demonstrate the operation of a quantum spin pump based on cyclic radio-frequency excitation of a GaAs quantum dot, including the ability to pump pure spin without pumping charge. The device takes advantage of bidirectional mesoscopic fluctuations of pumped current, made spin-dependent by the a......We demonstrate the operation of a quantum spin pump based on cyclic radio-frequency excitation of a GaAs quantum dot, including the ability to pump pure spin without pumping charge. The device takes advantage of bidirectional mesoscopic fluctuations of pumped current, made spin......-dependent by the application of an in-plane Zeeman field. Spin currents are measured by placing the pump in a focusing geometry with a spin-selective collector....

  16. Spin transport in epitaxial graphene

    Science.gov (United States)

    Tbd, -

    2014-03-01

    Spintronics is a paradigm focusing on spin as the information vector in fast and ultra-low-power non volatile devices such as the new STT-MRAM. Beyond its widely distributed application in data storage it aims at providing more complex architectures and a powerful beyond CMOS solution for information processing. The recent discovery of graphene has opened novel exciting opportunities in terms of functionalities and performances for spintronics devices. We will present experimental results allowing us to assess the potential of graphene for spintronics. We will show that unprecedented highly efficient spin information transport can occur in epitaxial graphene leading to large spin signals and macroscopic spin diffusion lengths (~ 100 microns), a key enabler for the advent of envisioned beyond-CMOS spin-based logic architectures. We will also show that how the device behavior is well explained within the framework of the Valet-Fert drift-diffusion equations. Furthermore, we will show that a thin graphene passivation layer can prevent the oxidation of a ferromagnet, enabling its use in novel humide/ambient low-cost processes for spintronics devices, while keeping its highly surface sensitive spin current polarizer/analyzer behavior and adding new enhanced spin filtering property. These different experiments unveil promising uses of graphene for spintronics.

  17. Development of magnetic drive packless valves for commercial purpose

    International Nuclear Information System (INIS)

    Hwang, Sung Tai; Choi, J. H.; Jeong, K. C.; Jeong, J. Y.; Choi, Y. D.; Kwon, S. W.; Kim, B. H.

    1997-01-01

    A study on development of magnetic drive packless valves for commercial purpose showed the results as follows: 1) characteristics and principle of the valve 2) study on the radial rays effecting to the permanent magnets 3) effects of temperature on the magnetic driving device a) temperature-dependency of the Nd-casting magnets b) effects of temperature on the heat releasing fins of high-temperature valve 4) optimization of torque a) arranging method of permanent magnets b) measuring method and results of torque 5) enlargement of magnetic rotating force a) experiments for the torque enlargement 6) calculation and pressure test for the pressure-resisting structure of magnetic power transmitting device a) calculation for the flat circular plates under pressure b) pressure test of the separating plate 7) design and manufacture of the valve 8) patent application. (author). 1 ref., 18 tabs., 38 figs

  18. Pros and cons of transcatheter aortic valve implantation (TAVI).

    Science.gov (United States)

    Terré, Juan A; George, Isaac; Smith, Craig R

    2017-09-01

    Transcatheter aortic valve implantation (TAVI) or replacement (TAVR) was recently approved by the FDA for intermediate risk patients with severe aortic stenosis (AS). This technique was already worldwide adopted for inoperable and high-risk patients. Improved device technology, imaging analysis and operator expertise has reduced the initial worrisome higher complications rate associated with TAVR, making it comparable to surgical aortic valve replacement (SAVR). However, many answers need to be addressed before adoption in lower risk patients. This paper highlights the pros and cons of TAVI based mostly on randomized clinical trials involving the two device platforms approved in the United States. We focused our analysis on metrics that will play a key role in expanding TAVR indication in healthier individuals. We review the significance and gave a perspective on paravalvular leak (PVL), valve performance, valve durability, leaflet thrombosis, stroke and pacemaker requirement.

  19. Valve for gas centrifuges

    Science.gov (United States)

    Hahs, Charles A.; Burbage, Charles H.

    1984-01-01

    The invention is a pneumatically operated valve assembly for simultaneously (1) closing gas-transfer lines connected to a gas centrifuge or the like and (2) establishing a recycle path between two of the lines so closed. The valve assembly is especially designed to be compact, fast-acting, reliable, and comparatively inexpensive. It provides large reductions in capital costs for gas-centrifuge cascades.

  20. Coanda effect in valves

    Directory of Open Access Journals (Sweden)

    Uruba Václav

    2017-01-01

    Full Text Available Coanda effect takes place in flow within valves diffuser for certain conditions. The valve plug in half-closed position forms wall-jet, which could be stable or instable, depending on geometry and other conditions. This phenomenon was subject of experimental study using time-resolved PIV technique. For the acquired data analysis the special spatio-temporal methods have been used.

  1. Magnetic resonance imaging in patients with heart valve prostheses

    International Nuclear Information System (INIS)

    Bachmann, R.; Juengehuelsing, M.; Schicha, H.; Deutsch, H.J.; Sechtem, U.; Hilger, H.H.

    1991-01-01

    Artifical valve prostheses are often regarded as a contraindication for magnetic resonance imaging (MRI), although preliminary in vitro studies suggested, that patients with these metallic implants might safely undergo MR examination. This study reports on the experience with a group of 89 patients with 100 heart valve prostheses who were examined by spin-echo MR and gradient-echo MR. MR examination was performed in all patients without complications. The spin-echo sequence showed advantages in the depiction of anatomical structures like paravalvular abcesses. Anatomical structures adjacent to the artificial valve were clearly visivle and the metal components of the valves showes no or only small artifacts. Artifacts were accentuated when using gradient-echo sequences. Gradient-echo sequences provided valuable information regarding the presence of valvular insufficiency. Physiological valvular regurgitation was easy to differentiate from pathological paravalvular or transvalvular regurgitation. These results demonstrate that patients with artificial valve prostheses can be imaged by MR without risk and that prosthesis-induced artifacts do no interfere with image interpretation. (orig.) [de

  2. Actuation and Control of a Micro Electrohydraulic Digital Servo Valve

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Z Q; Hu, M J; Pei, X; Ruan, J [MOE Key Laboratory of Mechanical Manufacture and Automation Zhejiang University of Technology, 310014 (China)

    2006-10-15

    Structure of the micro digital servo valve is given. A micro stepper motor is used as electrical-to-mechanical interface of the valve. A special mechanical device is designed to convert the rotation of the stepper motor into the linear motion of the spool. This moving conversion device functions through an eccentric ball head rigidly connected to the axis of the stepper motor and plugged into a slot at the central spool land. While the stepper motor rotates, the eccentric ball head will actuate the spool to make a linear motion. Unlike conventional servo or proportional valves, in which the spool is forced to central position by a spring force, when the current supply is switched off, the digital valve has a program to control the spool to its central position each time the electrical power supply is switched on or off. The two end screws are used to adjust the position of the sleeve to sustain a mechanical central position coincided with electrical central position given by the stepper motor after initialization. The adjustment has to be carried once before the first time the servo valve is put into service. This paper presents theoretical analysis and experimental study of dynamic characteristics of the proposed micro digital servo valve. Experimental results demonstrated that the valve takes the advantage of high accuracy and fast response.

  3. Actuation and Control of a Micro Electrohydraulic Digital Servo Valve

    International Nuclear Information System (INIS)

    Yu, Z Q; Hu, M J; Pei, X; Ruan, J

    2006-01-01

    Structure of the micro digital servo valve is given. A micro stepper motor is used as electrical-to-mechanical interface of the valve. A special mechanical device is designed to convert the rotation of the stepper motor into the linear motion of the spool. This moving conversion device functions through an eccentric ball head rigidly connected to the axis of the stepper motor and plugged into a slot at the central spool land. While the stepper motor rotates, the eccentric ball head will actuate the spool to make a linear motion. Unlike conventional servo or proportional valves, in which the spool is forced to central position by a spring force, when the current supply is switched off, the digital valve has a program to control the spool to its central position each time the electrical power supply is switched on or off. The two end screws are used to adjust the position of the sleeve to sustain a mechanical central position coincided with electrical central position given by the stepper motor after initialization. The adjustment has to be carried once before the first time the servo valve is put into service. This paper presents theoretical analysis and experimental study of dynamic characteristics of the proposed micro digital servo valve. Experimental results demonstrated that the valve takes the advantage of high accuracy and fast response

  4. Classification of heart valve condition using acoustic measurements

    Energy Technology Data Exchange (ETDEWEB)

    Clark, G. [Lawrence Livermore National Lab., CA (United States)

    1994-11-15

    Prosthetic heart valves and the many great strides in valve design have been responsible for extending the life spans of many people with serious heart conditions. Even though the prosthetic valves are extremely reliable, they are eventually susceptible to long-term fatigue and structural failure effects expected from mechanical devices operating over long periods of time. The purpose of our work is to classify the condition of in vivo Bjork-Shiley Convexo-Concave (BSCC) heart valves by processing acoustic measurements of heart valve sounds. The structural failures of interest for Bscc valves is called single leg separation (SLS). SLS can occur if the outlet strut cracks and separates from the main structure of the valve. We measure acoustic opening and closing sounds (waveforms) using high sensitivity contact microphones on the patient`s thorax. For our analysis, we focus our processing and classification efforts on the opening sounds because they yield direct information about outlet strut condition with minimal distortion caused by energy radiated from the valve disc.

  5. Heart failure - surgeries and devices

    Science.gov (United States)

    ... surgery; HF - surgery; Intra-aortic balloon pumps - heart failure; IABP - heart failure; Catheter based assist devices - heart failure ... problem may cause heart failure or make heart failure worse. Heart valve surgery may be needed to repair or ...

  6. A new approach to heart valve tissue engineering

    DEFF Research Database (Denmark)

    Kaasi, Andreas; Cestari, Idágene A.; Stolf, Noedir A G.

    2011-01-01

    The 'biomimetic' approach to tissue engineering usually involves the use of a bioreactor mimicking physiological parameters whilst supplying nutrients to the developing tissue. Here we present a new heart valve bioreactor, having as its centrepiece a ventricular assist device (VAD), which exposes...... chamber. Subsequently, applied vacuum to the pneumatic chamber causes the blood chamber to fill. A mechanical heart valve was placed in the VAD's inflow position. The tissue engineered (TE) valve was placed in the outflow position. The VAD was coupled in series with a Windkessel compliance chamber...

  7. Construction and characterization of valve for fast gas injection

    International Nuclear Information System (INIS)

    Ueda, M.; Rossi, J.O.; Aso, Y.; Mangueira, L.S.; Pereira, C.A.

    1989-01-01

    An electromagnetic valve for fast gas injection was built and characterized. This type of gas injection valve has been routinely applied to various plasma experiments: in magnetic confinement devices as TOKAMAK, RFP and Compact Toroids as well as intense ion beam and neutral particle generators. The valve is capable of injecting gas pulses with up to 80 m Torr peak pressure, rising time < 400 μs and duration time of 40 ms, in the present experimental set-up. It is easy to build and its components can be totally acquired in the country. (author)

  8. Large spin accumulation due to spin-charge coupling across a break-junction

    Science.gov (United States)

    Chen, Shuhan; Zou, Han; Chui, Siu-Tat; Ji, Yi

    2013-03-01

    We investigate large spin signals in break-junction nonlocal spin valves (NLSV). The break-junction is a nanometer-sized vacuum tunneling gap between the spin detector and the nonmagnetic channel, formed by electro-static discharge. The spin signals can be either inverted or non-inverted and the magnitudes are much larger than those of standard NLSV. Spin signals with high percentage values (10% - 0%) have been observed. When the frequency of the a.c. modulation is varied, the absolute magnitudes of signals remain the same although the percentage values change. These observations affirm the nonlocal nature of the measurements and rule out local magnetoresistive effects. Owing to the spin-charge coupling across the break-junction, the spin accumulation in a ferromagnet splits into two terms. One term decays on the charge screening length (0.1 nm) and the other decays on the spin diffusion length (10 nm nm). The magnitude of the former is proportional to the resistance of the junction. Therefore a highly resistive break-junction leads to a large spin accumulation and thereby a large spin signal. The signs of the spin signal are determined by the relationship between spin-dependent conductivities, diffusion constants, and density of states of the ferromagnet. This work was supported by US DOE grant No. DE-FG02-07ER46374.

  9. Study on high reliability safety valve for railway vehicle

    Science.gov (United States)

    Zhang, Xuan; Chen, Ruikun; Zhang, Shixi; Xu, BuDu

    2017-09-01

    Now, the realization of most of the functions of the railway vehicles rely on compressed air, so the demand for compressed air is growing higher and higher. This safety valve is a protection device for pressure limitation and pressure relief in an air supply system of railway vehicles. I am going to introduce the structure, operating principle, research and development process of the safety valve designed by our company in this document.

  10. Quantum size effects on spin-transfer torque in a double barrier magnetic tunnel junction with a nonmagnetic-metal (semiconductor) spacer

    International Nuclear Information System (INIS)

    Daqiq, Reza; Ghobadi, Nader

    2016-01-01

    We study the quantum size effects of an MgO-based double barrier magnetic tunnel junction with a nonmagnetic-metal (DBMTJ-NM) (semiconductor (DBMTJ-SC)) spacer on the charge current and the spin-transfer torque (STT) components using non-equilibrium Green's function (NEGF) formalism. The results show oscillatory behavior due to the resonant tunneling effect depending on the structure parameters. We find that the charge current and the STT components in the DBMTJ-SC demonstrate the magnitude enhancement in comparison with the DBMTJ-NM. The bias dependence of the STT components in a DBMTJ-NM shows different behavior in comparison with spin valves and conventional MTJs. Therefore, by choosing a specific SC spacer with suitable thickness in a DBMTJ the charge current and the STT components significantly increase so that one can design a device with high STT and faster magnetization switching. - Highlights: • The quantum size effects are studied in double barrier magnetic tunnel junctions. • Spin torque (ST) components oscillate for increasing of middle spacer thicknesses. • Due to the resonant tunneling in the quantum well, oscillations have appeared. • By replacement a metal spacer with a semiconductor (ZnO) ST has increased. • The ST components vs. bias show gradually decreasing unlike spin valves or MTJs.

  11. Quantum size effects on spin-transfer torque in a double barrier magnetic tunnel junction with a nonmagnetic-metal (semiconductor) spacer

    Energy Technology Data Exchange (ETDEWEB)

    Daqiq, Reza; Ghobadi, Nader

    2016-07-15

    We study the quantum size effects of an MgO-based double barrier magnetic tunnel junction with a nonmagnetic-metal (DBMTJ-NM) (semiconductor (DBMTJ-SC)) spacer on the charge current and the spin-transfer torque (STT) components using non-equilibrium Green's function (NEGF) formalism. The results show oscillatory behavior due to the resonant tunneling effect depending on the structure parameters. We find that the charge current and the STT components in the DBMTJ-SC demonstrate the magnitude enhancement in comparison with the DBMTJ-NM. The bias dependence of the STT components in a DBMTJ-NM shows different behavior in comparison with spin valves and conventional MTJs. Therefore, by choosing a specific SC spacer with suitable thickness in a DBMTJ the charge current and the STT components significantly increase so that one can design a device with high STT and faster magnetization switching. - Highlights: • The quantum size effects are studied in double barrier magnetic tunnel junctions. • Spin torque (ST) components oscillate for increasing of middle spacer thicknesses. • Due to the resonant tunneling in the quantum well, oscillations have appeared. • By replacement a metal spacer with a semiconductor (ZnO) ST has increased. • The ST components vs. bias show gradually decreasing unlike spin valves or MTJs.

  12. Spin current

    CERN Document Server

    Valenzuela, Sergio O; Saitoh, Eiji; Kimura, Takashi

    2017-01-01

    Since the discovery of the giant magnetoresistance effect in magnetic multilayers in 1988, a new branch of physics and technology, called spin-electronics or spintronics, has emerged, where the flow of electrical charge as well as the flow of electron spin, the so-called “spin current,” are manipulated and controlled together. The physics of magnetism and the application of spin current have progressed in tandem with the nanofabrication technology of magnets and the engineering of interfaces and thin films. This book aims to provide an introduction and guide to the new physics and applications of spin current, with an emphasis on the interaction between spin and charge currents in magnetic nanostructures.

  13. Interfacial spin-orbit splitting and current-driven spin torque in anisotropic tunnel junctions

    KAUST Repository

    Manchon, Aurelien

    2011-05-17

    Spin transport in magnetic tunnel junctions comprising a single magnetic layer in the presence of interfacial spin-orbit interaction (SOI) is investigated theoretically. Due to the presence of interfacial SOI, a current-driven spin torque can be generated at the second order in SOI, even in the absence of an external spin polarizer. This torque possesses two components, one in plane and one perpendicular to the plane of rotation, that can induce either current-driven magnetization switching from an in-plane to out-of-plane configuration or magnetization precessions, similar to spin transfer torque in spin valves. Consequently, it appears that it is possible to control the magnetization steady state and dynamics by either varying the bias voltage or electrically modifying the SOI at the interface.

  14. Reduction of ballistic spin scattering in a spin-FET using stray electric fields

    International Nuclear Information System (INIS)

    Nemnes, G A; Manolescu, A; Gudmundsson, V

    2012-01-01

    The quasi-bound states which appear as a consequence of the Rashba spin-orbit (SO) coupling, introduce a strongly irregular behavior of the spin-FET conductance at large Rashba parameter. Moreover, the presence of the bulk inversion asymmetry, i.e. the Dresselhaus SO coupling, may compromise the spin-valve effect even at small values of the Rashba parameter. However, by introducing stray electric fields in addition to the SO couplings, we show that the effect of the SO induced quasi-bound states can be tuned. The oscillations of the spin-resolved conductance become smoother and the control of the spin-FET characteristics becomes possible. For the calculations we employ a multi-channel scattering formalism, based on the R-matrix method extended to spin transport, in the presence of Rashba and Dresselhaus SO couplings.

  15. Spin doctoring

    OpenAIRE

    Vozková, Markéta

    2011-01-01

    1 ABSTRACT The aim of this text is to provide an analysis of the phenomenon of spin doctoring in the Euro-Atlantic area. Spin doctors are educated people in the fields of semiotics, cultural studies, public relations, political communication and especially familiar with the infrastructure and the functioning of the media industry. Critical reflection of manipulative communication techniques puts spin phenomenon in historical perspective and traces its practical use in today's social communica...

  16. Effect of the sinus of valsalva on the closing motion of bileaflet prosthetic heart valves.

    Science.gov (United States)

    Ohta, Y; Kikuta, Y; Shimooka, T; Mitamura, Y; Yuhta, T; Dohi, T

    2000-04-01

    Conventional bileaflet prosthetic mechanical heart valves close passively with backflow. Naturally, the valve has problems associated with closure, such as backflow, water hammer effect, and fracture of the leaflet. On the other hand, in the case of the natural aortic valve, the vortex flow in the sinus of Valsalva pushes the leaflet to close, and the valve starts the closing motion earlier than the prosthetic valve as the forward flow decelerates. This closing mechanism is thought to decrease backflow at valve closure. In this study, we propose a new bileaflet mechanical valve resembling a drawbridge in shape, and the prototype valve was designed so that the leaflet closes with the help of the vortex flow in the sinus. The test valve was made of aluminum alloy, and its closing motion was compared to that of the CarboMedics (CM) valve. Both valves were driven by a computer controlled hydraulic mock circulator and were photographed at 648 frames/s by a high speed charge-coupled device (CCD) camera. Each frame of the valve motion image was analyzed with a personal computer, and the opening angles were measured. The flow rate was set as 5.0 L/min. The system was pulsed with 70 bpm, and the systolic/diastolic ratio was 0.3. Glycerin water was used as the circulation fluid at room temperature, and polystyrene particles were used to visualize the streamline. The model of the sinus of Valsalva was made of transparent silicone rubber. As a result, high speed video analysis showed that the test valve started the closing motion 41 ms earlier than the CM valve, and streamline analysis showed that the test valve had a closing mechanism similar to the natural one with the effect of vortex flow. The structure of the test valve was thought to be effective for soft closure and could solve problems associated with closure.

  17. Spin voltage generation through optical excitation of complementary spin populations

    Science.gov (United States)

    Bottegoni, Federico; Celebrano, Michele; Bollani, Monica; Biagioni, Paolo; Isella, Giovanni; Ciccacci, Franco; Finazzi, Marco

    2014-08-01

    By exploiting the spin degree of freedom of carriers inside electronic devices, spintronics has a huge potential for quantum computation and dissipationless interconnects. Pure spin currents in spintronic devices should be driven by a spin voltage generator, able to drive the spin distribution out of equilibrium without inducing charge currents. Ideally, such a generator should operate at room temperature, be highly integrable with existing semiconductor technology, and not interfere with other spintronic building blocks that make use of ferromagnetic materials. Here we demonstrate a device that matches these requirements by realizing the spintronic equivalent of a photovoltaic generator. Whereas a photovoltaic generator spatially separates photoexcited electrons and holes, our device exploits circularly polarized light to produce two spatially well-defined electron populations with opposite in-plane spin projections. This is achieved by modulating the phase and amplitude of the light wavefronts entering a semiconductor (germanium) with a patterned metal overlayer (platinum). The resulting light diffraction pattern features a spatially modulated chirality inside the semiconductor, which locally excites spin-polarized electrons thanks to electric dipole selection rules.

  18. Transcatheter Aortic Valve Replacement for Degenerative Bioprosthetic Surgical Valves

    DEFF Research Database (Denmark)

    Dvir, Danny; Webb, John; Brecker, Stephen

    2012-01-01

    Transcatheter aortic valve-in-valve implantation is an emerging therapeutic alternative for patients with a failed surgical bioprosthesis and may obviate the need for reoperation. We evaluated the clinical results of this technique using a large, worldwide registry....

  19. NRC valve performance test program - check valve testing

    International Nuclear Information System (INIS)

    Jeanmougin, N.M.

    1987-01-01

    The Valve Performance Test Program addresses the current requirements for testing of pressure isolation valves (PIVs) in light water reactors. Leak rate monitoring is the current method used by operating commercial power plants to survey the condition of their PIVs. ETEC testing of three check valves (4-inch, 6-inch, and 12-inch nominal diameters) indicates that leak rate testing is not a reliable method for detecting impending valve failure. Acoustic emission monitoring of check valves shows promise as a method of detecting loosened internals damage. Future efforts will focus on evaluation of acoustic emission monitoring as a technique for determining check valve condition. Three gate valves also will be tested to evaluate whether the check valve results are applicable to gate type PIVs

  20. Possibility of Cooper-pair formation controlled by multi-terminal spin injection

    Science.gov (United States)

    Ohnishi, K.; Sakamoto, M.; Ishitaki, M.; Kimura, T.

    2018-03-01

    A multi-terminal lateral spin valve consisting of three ferromagnetic nanopillars on a Cu/Nb bilayer has been fabricated. We investigated the influence of the spin injection on the superconducting properties at the Cu/Nb interface. The non-local spin valve signal exhibits a clear spin insulation signature due to the superconducting gap of the Nb. The magnitude of the spin signal is found to show the probe configuration dependence. From the careful analysis of the bias current dependence, we found the suppression of the superconductivity due to the exchange interaction between the Cooper pair and accumulated spin plays an important role in the multi-terminal spin injections. We also discuss about the possibility of the Cooper-pair formation due to the spin injection from the two injectors with the anti-parallel alignment.