WorldWideScience

Sample records for net ferromagnetic moment

  1. Ferroelectricity with Ferromagnetic Moment in Orthoferrites

    Science.gov (United States)

    Tokunaga, Yusuke

    2010-03-01

    Exotic multiferroics with gigantic magnetoelectric (ME) coupling have recently been attracting broad interests from the viewpoints of both fundamental physics and possible technological application to next-generation spintronic devices. To attain a strong ME coupling, it would be preferable that the ferroelectric order is induced by the magnetic order. Nevertheless, the magnetically induced ferroelectric state with the spontaneous ferromagnetic moment is still quite rare apart from a few conical-spin multiferroics. To further explore multiferroic materials with both the strong ME coupling and spontaneous magnetization, we focused on materials with magnetic structures other than conical structure. In this talk we present that the most orthodox perovskite ferrite systems DyFeO3 and GdFeO3 have ``ferromagnetic-ferroelectric,'' i.e., genuinely multiferroic states in which weak ferromagnetic moment is induced by Dzyaloshinskii-Moriya interaction working on Fe spins and electric polarization originates from the striction due to symmetric exchange interaction between Fe and Dy (Gd) spins [1] [2]. Both materials showed large electric polarization (>0.1 μC/cm^2) and strong ME coupling. In addition, we succeeded in mutual control of magnetization and polarization with electric- and magnetic-fields in GdFeO3, and attributed the controllability to novel, composite domain wall structure. [4pt] [1] Y. Tokunaga et al., Phys. Rev. Lett. 101, 097205 (2008). [0pt] [2] Y. Tokunaga et al., Nature Mater. 8, 558 (2009).

  2. Higher-moment measurements of net-kaon, net-charge and net-proton multiplicity distributions at STAR

    International Nuclear Information System (INIS)

    Sarkar, Amal

    2014-01-01

    In this paper, we report the measurements of the various moments, such as mean, standard deviation (σ), skewness (S) and kurtosis (κ) of the net-kaon, net-charge and net-proton multiplicity distributions at mid-rapidity in Au + Au collisions from √(s NN )=7.7 to 200 GeV with the STAR experiment at RHIC. This work has been done with the aim to locate the critical point on the QCD phase diagram. These moments and their products are related to the thermodynamic susceptibilities of conserved quantities such as net baryon number, net charge, and net strangeness as well as to the correlation length of the system which diverges in an ideal infinite thermodynamic system at the critical point. For a finite system, existing for a finite time, a non-monotonic behavior of these variables would indicate the presence of the critical point. Furthermore, we also present the moment products Sσ, κσ 2 of net-kaon, net-charge and net-proton multiplicity distributions as a function of collision centrality and energy. The energy and the centrality dependence of higher moments and their products have been compared with different models

  3. Laser-induced ultrafast demagnetization time and spin moment in ferromagnets: First-principles calculation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, G. P., E-mail: gpzhang@indstate.edu [Department of Physics, Indiana State University, Terre Haute, Indiana 47809 (United States); Si, M. S. [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); George, Thomas F. [Office of the Chancellor and Center for Nanoscience, Departments of Chemistry and Biochemistry and Physics and Astronomy, University of Missouri-St. Louis, St. Louis, Missouri 63121 (United States)

    2015-05-07

    When a laser pulse excites a ferromagnet, its spin undergoes a dramatic change. The initial demagnetization process is very fast. Experimentally, it is found that the demagnetization time is related to the spin moment in the sample. In this study, we employ the first-principles method to directly simulate such a process. We use the fixed spin moment method to change the spin moment in ferromagnetic nickel, and then we employ the Liouville equation to couple the laser pulse to the system. We find that in general the dependence of demagnetization time on the spin moment is nonlinear: It decreases with the spin moment up to a point, after which an increase with the spin moment is observed, followed by a second decrease. To understand this, we employ an extended Heisenberg model, which includes both the exchange interaction and spin-orbit coupling. The model directly links the demagnetization rate to the spin moment itself and demonstrates analytically that the spin relaxes more slowly with a small spin moment. A future experimental test of our predictions is needed.

  4. Strong coupling between localized 5f moments and itinerant quasiparticles in the ferromagnetic superconductor UGe2

    Science.gov (United States)

    Zhang, Wen; Liu, Yi; Wang, Xiaoying; Zhang, Yun; Xie, Donghua

    2018-03-01

    The heavy fermion physics arises from the complex interplay of nearly localized 4f/5f electrons and itinerant band-like ones, yielding heavy quasiparticles with an effective mass about 100 times (or more) of the bare electrons. Recently, experimental and theoretical investigations point out a localized and delocalized dual nature in actinide compounds, where itinerant quasiparticles account for the unconventional superconductivity in the vicinity of a magnetic instability. Here we report the strong coupling between localized 5f moments and itinerant quasiparticles in the ferromagnetic superconductor UGe2. The coupling is nearly antiferromagnetic. As embedded in the ferromagnetic matrix of localized 5f moments below {T}{{C}}≈ 52 {{K}}, this coupling leads to short-range dynamic correlations of heavy quasiparticles, characterized by fluctuations of magnetic clusters. Those cluster-like spins of itinerant quasiparticles show a broad hump of magnetization at {T}X≈ 28 {{K}}, which is typical for the spin-glass freezing. Thus, our results present the direct observation of itinerant quasiparticles coexisting with localized 5f moments by conventional magnetic measurements, providing a new route into the coexistence between ferromagnetism and superconductivity in heavy fermion systems. Project supported by the National Natural Science Foundation of China (Grant No. 11404297), the Science Challenge Project (Grant No. TZ2016004), and the Science and Technology Foundation of China Academy of Engineering Physics (Grant Nos. 2013B0301050 and 2014A0301013).

  5. Adaptive Elastic Net for Generalized Methods of Moments.

    Science.gov (United States)

    Caner, Mehmet; Zhang, Hao Helen

    2014-01-30

    Model selection and estimation are crucial parts of econometrics. This paper introduces a new technique that can simultaneously estimate and select the model in generalized method of moments (GMM) context. The GMM is particularly powerful for analyzing complex data sets such as longitudinal and panel data, and it has wide applications in econometrics. This paper extends the least squares based adaptive elastic net estimator of Zou and Zhang (2009) to nonlinear equation systems with endogenous variables. The extension is not trivial and involves a new proof technique due to estimators lack of closed form solutions. Compared to Bridge-GMM of Caner (2009), we allow for the number of parameters to diverge to infinity as well as collinearity among a large number of variables, also the redundant parameters set to zero via a data dependent technique. This method has the oracle property, meaning that we can estimate nonzero parameters with their standard limit and the redundant parameters are dropped from the equations simultaneously. Numerical examples are used to illustrate the performance of the new method.

  6. Uniaxial ferromagnetism of local uranium moments in hexagonal UBeGe

    Science.gov (United States)

    Gumeniuk, Roman; Yaresko, Alexander N.; Schnelle, Walter; Nicklas, Michael; Kvashnina, Kristina O.; Hennig, Christoph; Grin, Yuri; Leithe-Jasper, Andreas

    2018-05-01

    The new intermetallic uranium beryllium germanide UBeGe and its thorium analogon ThBeGe crystallize with the hexagonal ZrBeSi type of structure. Studies of magnetic, thermal, and transport properties were performed on polycrystalline samples between 1.8 and 750K. UBeGe is a uniaxial ferromagnet and there are indications for two magnetic transitions at TC(1 )≈160 K and TC(2 )≈150 K . The high paramagnetic effective moment μeff≈3.1 μB , x-ray absorption near-edge spectroscopy (XANES, 17-300 K), as well as theoretical DFT calculations indicate localized U 5 f2 states in UBeGe. ThBeGe is a diamagnetic metallic material with low density of states at the Fermi level.

  7. Origin of the net magnetic moment in LaCoO3

    Science.gov (United States)

    Kaminsky, G. M.; Belanger, D. P.; Ye, F.; Fernandez-Baca, J. A.; Wang, J.; Matsuda, M.; Yan, J.-Q.

    2018-01-01

    We use polarized neutron scattering to characterize the Bragg scattering intensity below TC=89.5 K at the (1,0,0) pseudocubic nuclear Bragg point of LaCoO3. Upon cooling in a field (FC), a net magnetic moment is apparent in Bragg scattering intensity, just as it was in previous magnetization measurements. Critical behavior associated with the net moment near TC upon cooling in small applied fields rapidly rounds with increasing field strength. We show, using a mean-field calculation, that this net moment can develop in a metastable state that forms upon FC, even when all the interactions in the system are antiferromagnetic.

  8. Origin of room temperature ferromagnetic moment in Rh-rich [Rh/Fe] multilayer thin films

    International Nuclear Information System (INIS)

    Kande, Dhishan; Laughlin, David; Zhu Jiangang

    2010-01-01

    B2 ordered FeRh thin films switch from antiferromagnetic (AFM) to ferromagnetic (FM) state on heating above 350 K and switch back on cooling, with a hysteresis. This property makes FeRh a very attractive choice as a write-assist layer material for low temperature heat assisted magnetic recording (HAMR) media. Studies have shown that as we decrease the thickness of the FeRh films, the B2 phase is no longer AFM even below 350 K and there is a thickness dependant FM stabilization of the B2 phase. It was also proved that slightly Rh-richer compositions (>50 at. % Rh) were more preferable to stabilize the AFM phase. The current study focuses on growing highly ordered FeRh films by alternate layer rf sputtering of thin layers of iron and rhodium onto a heated substrate. It has been shown that films with rhodium content beyond 55 at. % contain a disordered bcc FM phase which gives rise to residual moment at room temperature even for thicker films.

  9. Ferromagnetically coupled local moments along an extended line defect in graphene

    Science.gov (United States)

    White, Carter T.; Vasudevan, Smitha; Gunlycke, Daniel

    2011-03-01

    Recently an extended line defect was observed composed of octagonal and pentagonal carbon rings embedded in a graphene sheet [Nat. Nanotech. 5, 326 (2010)]. We report results of studies we have made of this defect using both first-principles and semi-empirical methods. Two types of boundary-localized states arising from the defect are identified. The first (second) type has eigenstates with wavefunctions that are anti- symmetric (symmetric) with respect to a mirror plane that is perpendicular to the graphene sheet and passes through the line defect center line. The boundary-localized anti-symmetric states are shown to be intimately connected to the zigzag edge states of semi-infinite graphene. They exhibit little dispersion along the defect line and lie close to the Fermi level giving rise to a spontaneous spin polarization along the defect once electron-electron interactions are included at the level of a mean field approximation to a Hubbard Model. Within this approach, symmetry requires that the principal moments couple ferromagnetically both along and across the line defect leading to approximately 2/3 more up than down spin electrons per defect repeat unit. This work was supported by ONR, directly and through NRL.

  10. Disorder dependence of the magnetic moment of the half-metallic ferromagnet NiMnSb from first principles

    International Nuclear Information System (INIS)

    Orgassa, D.; Fujiwara, H.; Schulthess, T. C.; Butler, W. H.

    2000-01-01

    Using half-metallic ferromagnets in spin-dependent devices, like spin valves and ferromagnetic tunnel junctions, is expected to increase the device performance. However, using the half-metallic ferromagnet NiMnSb in such devices led to much less than ideal results. One of the possible sources for this behavior is atomic disorder. First-principles calculations of the influence of atomic disorder on the electronic structure of NiMnSb underline the sensitivity of half-metallic properties in NiMnSb to atomic disorder. In this article, we report on the disorder dependence of the total magnetic moment calculated by applying the layer Korringa-Kohn-Rostoker method in conjunction with the coherent potential approximation. We consider the following types of disorder: (1) intermixing of Ni and Mn, (2) partial occupancy of a normally vacant lattice site by Ni and Mn, and (3) partial occupancy of this site by Mn and Sb. In all cases the composition is kept stoichiometric. All three types of disorder decrease the moment monotonically with increasing disorder levels. For the experimentally seen disorder of 5% Mn and 5% Sb on the normally vacant lattice site, the total moment is decreased by 4.1%. The results suggest that precise measurement of the saturation magnetization of NiMnSb thin films can give information on the disorder. (c) 2000 American Institute of Physics

  11. Half-metallic ferromagnetism with low magnetic moment in zinc-blende TiBi from first-principles calculations

    International Nuclear Information System (INIS)

    Chen, Zhi-Yuan; Xu, Bin; Gao, G.Y.

    2013-01-01

    The structural, electronic and magnetic properties of zinc-blende TiBi are investigated by using the first-principles full-potential linearized augmented plane-wave method. It is found that zinc-blende TiBi exhibits half-metallic ferromagnetism with the energy gap of 1.39 eV in the minority-spin channel. The calculated total magnetic moment of 1.00 µ B per formula unit mainly originates from the Ti atom. We also show that the half-metallicity of zinc-blende TiBi can be maintained up to 3% compression and 5% expansion of lattice constant with respect to the equilibrium lattice, and zinc-blende TiBi is still half-metallic when the spin–orbit coupling is considered. The robust half-metallicity and low magnetic moment make zinc-blende TiBi a potential candidate for spintronic applications. - Highlights: • Half-metallic ferromagnetism in zinc-blende TiBi. • Zinc-blende TiBi has low magnetic moment of 1.00 µ B /f.u. • Spin–orbit coupling does not destroy the half-metallicity of zinc-blende TiBi

  12. Measurement of net electric charge and dipole moment of dust aggregates in a complex plasma.

    Science.gov (United States)

    Yousefi, Razieh; Davis, Allen B; Carmona-Reyes, Jorge; Matthews, Lorin S; Hyde, Truell W

    2014-09-01

    Understanding the agglomeration of dust particles in complex plasmas requires knowledge of basic properties such as the net electrostatic charge and dipole moment of the dust. In this study, dust aggregates are formed from gold-coated mono-disperse spherical melamine-formaldehyde monomers in a radiofrequency (rf) argon discharge plasma. The behavior of observed dust aggregates is analyzed both by studying the particle trajectories and by employing computer models examining three-dimensional structures of aggregates and their interactions and rotations as induced by torques arising from their dipole moments. These allow the basic characteristics of the dust aggregates, such as the electrostatic charge and dipole moment, as well as the external electric field, to be determined. It is shown that the experimental results support the predicted values from computer models for aggregates in these environments.

  13. Spin exchange between ion probes and localized moments in ferromagnets as the origin of transient fields

    International Nuclear Information System (INIS)

    Hagelberg, F.; Das, T.P.; Speidel, K.

    1993-01-01

    The transient field phenomenon has been ascribed to a polarization transfer between the electrons of the ionic projectiles and the surplus of majority spin electrons of the ferromagnetic host over the minority spin electrons. Earlier attempts to explain this crucial process failed to account for the order of magnitude of the experimentally observed transient field strengths. A recent model which proposes spin exchange scattering between bound projectile electrons and quasifree host electrons as the mechanism of polarization transfer arrives at the correct orders of magnitude but is in conflict with the weak velocity dependence of the experimental polarization, exhibiting a strongly decreasing behavior with increasing velocity. The new model presented here proposes spin exchange between the ionic shell and localized electrons of the ferromagnet as a more adequate approach to the problem. It is shown that calculations involving hydrogenlike ions explain the size of the experimentally observed polarization effects as well as their velocity dependence for various ion probes traversing thin iron foils

  14. First study of the negative binomial distribution applied to higher moments of net-charge and net-proton multiplicity distributions

    International Nuclear Information System (INIS)

    Tarnowsky, Terence J.; Westfall, Gary D.

    2013-01-01

    A study of the first four moments (mean, variance, skewness, and kurtosis) and their products (κσ 2 and Sσ) of the net-charge and net-proton distributions in Au + Au collisions at √(s NN )=7.7–200 GeV from HIJING simulations has been carried out. The skewness and kurtosis and the collision volume independent products κσ 2 and Sσ have been proposed as sensitive probes for identifying the presence of a QCD critical point. A discrete probability distribution that effectively describes the separate positively and negatively charged particle (or proton and anti-proton) multiplicity distributions is the negative binomial (or binomial) distribution (NBD/BD). The NBD/BD has been used to characterize particle production in high-energy particle and nuclear physics. Their application to the higher moments of the net-charge and net-proton distributions is examined. Differences between κσ 2 and a statistical Poisson assumption of a factor of four (for net-charge) and 40% (for net-protons) can be accounted for by the NBD/BD. This is the first application of the properties of the NBD/BD to describe the behavior of the higher moments of net-charge and net-proton distributions in nucleus–nucleus collisions

  15. Non-Fermi Liquid Behavior Close to a Quantum Critical Point in a Ferromagnetic State without Local Moments

    Directory of Open Access Journals (Sweden)

    E. Svanidze

    2015-03-01

    Full Text Available A quantum critical point (QCP occurs upon chemical doping of the weak itinerant ferromagnet Sc_{3.1}In. Remarkable for a system with no local moments, the QCP is accompanied by non-Fermi liquid behavior, manifested in the logarithmic divergence of the specific heat both in the ferro-and the paramagnetic states, as well as linear temperature dependence of the low-temperature resistivity. With doping, critical scaling is observed close to the QCP, as the critical exponents δ, γ, and β have weak composition dependence, with δ nearly twice and β almost half of their respective mean-field values. The unusually large paramagnetic moment μ_{PM}∼1.3μ_{B}/F.U. is nearly composition independent. Evidence for strong spin fluctuations, accompanying the QCP at x_{c}=0.035±0.005, may be ascribed to the reduced dimensionality of Sc_{3.1}In, associated with the nearly one-dimensional Sc-In chains.

  16. Higher moments of net kaon multiplicity distributions at RHIC energies for the search of QCD Critical Point at STAR

    Directory of Open Access Journals (Sweden)

    Sarkar Amal

    2013-11-01

    Full Text Available In this paper we report the measurements of the various moments mean (M, standard deviation (σ skewness (S and kurtosis (κ of the net-Kaon multiplicity distribution at midrapidity from Au+Au collisions at √sNN = 7.7 to 200 GeV in the STAR experiment at RHIC in an effort to locate the critical point in the QCD phase diagram. These moments and their products are related to the thermodynamic susceptibilities of conserved quantities such as net baryon number, net charge, and net strangeness as also to the correlation length of the system. A non-monotonic behavior of these variable indicate the presence of the critical point. In this work we also present the moments products Sσ, κσ2 of net-Kaon multiplicity distribution as a function of collision centrality and energies. The energy and the centrality dependence of higher moments of net-Kaons and their products have been compared with it0s Poisson expectation and with simulations from AMPT which does not include the critical point. From the measurement at all seven available beam energies, we find no evidence for a critical point in the QCD phase diagram for √sNN below 200 GeV.

  17. Net-section limit moments and approximate J estimates for circumferential cracks at the interface between elbows and pipes

    International Nuclear Information System (INIS)

    Song, Tae-Kwang; Kim, Yun-Jae; Oh, Chang-Kyun; Jin, Tae-Eun; Kim, Jong-Sung

    2009-01-01

    This paper firstly presents net-section limit moments for circumferential through-wall and part-through surface cracks at the interface between elbows and attached straight pipes under in-plane bending. Closed-form solutions are proposed based on fitting results from small strain FE limit analyses using elastic-perfectly plastic materials. Net-section limit moments for circumferential cracks at the interface between elbows and attached straight pipes are found to be close to those for cracks in the centre of elbows, implying that the location of the circumferential crack within an elbow has a minimal effect on the net-section limit moment. Accordingly it is also found that the assumption that the crack locates in a straight pipe could significantly overestimate the net-section limit load (and thus maximum load-carrying capacity) of the cracked component. Based on the proposed net-section limit moment, a method to estimate elastic-plastic J based on the reference stress approach is proposed for circumferential cracks at the interface between elbows and attached straight pipes under in-plane bending.

  18. Net joint moments and muscle activation in barbell squats without and with restricted anterior leg rotation.

    Science.gov (United States)

    Chiu, Loren Z F; vonGaza, Gabriella L; Jean, Liane M Y

    2017-01-01

    Muscle utilisation in squat exercise depends on technique. The purpose of this study was to compare net joint moments (NJMs) and muscle activation during squats without and with restricted leg dorsiflexion. Experienced men (n = 5) and women (n = 4) performed full squats at 80% one repetition maximum. 3D motion analysis, force platform and (EMG) data were collected. Restricting anterior leg rotation reduced anterior leg (P = 0.001) and posterior thigh (P squat depth, ankle plantar flexor (P squats. Hip extensor NJM (P = 0.14) was not different between squat types at maximum squat depth. Vastus lateralis (P > 0.05), vastus medialis (P > 0.05) and rectus femoris (P > 0.05) EMG were not different between squat types. Unrestricted squats have higher ankle plantar flexor and knee extensor NJM than previously reported from jumping and landing. However, ankle plantar flexor and knee extensor NJM are lower in restricted squats than previous studies of jumping and landing. The high NJM in unrestricted squat exercise performed through a full range of motion suggests this squat type would be more effective to stimulate adaptations in the lower extremity musculature than restricted squats.

  19. Extraction of moments of net-particle event-by-event fluctuations in the CBM experiment

    Energy Technology Data Exchange (ETDEWEB)

    Vovchenko, Volodymyr [Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany); Goethe University, Frankfurt am Main (Germany); Taras Shevchenko University, Kyiv (Ukraine); Kisel, Ivan [Frankfurt Institute for Advanced Studies, Frankfurt am Main (Germany); Goethe University, Frankfurt am Main (Germany); Collaboration: CBM-Collaboration

    2016-07-01

    The future CBM experiment at FAIR will employ high intensity beams and large acceptance detectors in order to study the properties of the strongly interacting matter produced in heavy-ion collisions at high baryon densities. The search for the conjectured critical point of QCD is one the important tasks. It is predicted from statistical physics that higher moments of event-by-event fluctuations are very sensitive to the proximity of the critical point. This argument is explicitly demonstrated with the van der Waals equation of state. Thus, it was suggested that higher moments of fluctuations of conserved charges can be used as probes for the critical behavior. The statistical convergence of cumulants of different order is explored. The extraction of scaled variance, skewness, and kurtosis of proton distribution from simulated UrQMD events is performed and the efficiency correction described by binomial distribution is accounted for. The validity of this correction is tested with different modelings of the CBM detector response: from binomial distribution with fluctuating event-by-event efficiency to a full-scale GEANT simulation. The obtained results indicate that a more elaborate efficiency correction is needed in order to accurately reconstruct moments of higher orders.

  20. A differential dielectric spectroscopy setup to measure the electric dipole moment and net charge of colloidal quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Kortschot, R. J.; Bakelaar, I. A.; Erné, B. H.; Kuipers, B. W. M., E-mail: B.W.M.Kuipers@uu.nl [Van ' t Hoff Laboratory for Physical and Colloid Chemistry, Debye Institute for Nanomaterials Science, Utrecht University, Padualaan 8, 3584 CH Utrecht (Netherlands)

    2014-03-15

    A sensitive dielectric spectroscopy setup is built to measure the response of nanoparticles dispersed in a liquid to an alternating electric field over a frequency range from 10{sup −2} to 10{sup 7} Hz. The measured complex permittivity spectrum records both the rotational dynamics due to a permanent electric dipole moment and the translational dynamics due to net charges. The setup consists of a half-transparent capacitor connected in a bridge circuit, which is balanced on pure solvent only, using a software-controlled compensating voltage. In this way, the measured signal is dominated by the contributions of the nanoparticles rather than by the solvent. We demonstrate the performance of the setup with measurements on a dispersion of colloidal CdSe quantum dots in the apolar liquid decalin.

  1. A differential dielectric spectroscopy setup to measure the electric dipole moment and net charge of colloidal quantum dots.

    Science.gov (United States)

    Kortschot, R J; Bakelaar, I A; Erné, B H; Kuipers, B W M

    2014-03-01

    A sensitive dielectric spectroscopy setup is built to measure the response of nanoparticles dispersed in a liquid to an alternating electric field over a frequency range from 10(-2) to 10(7) Hz. The measured complex permittivity spectrum records both the rotational dynamics due to a permanent electric dipole moment and the translational dynamics due to net charges. The setup consists of a half-transparent capacitor connected in a bridge circuit, which is balanced on pure solvent only, using a software-controlled compensating voltage. In this way, the measured signal is dominated by the contributions of the nanoparticles rather than by the solvent. We demonstrate the performance of the setup with measurements on a dispersion of colloidal CdSe quantum dots in the apolar liquid decalin.

  2. The Physics of Ferromagnetism

    CERN Document Server

    Miyazaki, Terunobu

    2012-01-01

    This book covers both basic physics of ferromagnetism such as magnetic moment, exchange coupling, magnetic anisotropy and recent progress in advanced ferromagnetic materials. Special interests are focused on NdFeB permanent magnets and the materials studied in the field of spintronics. In the latter, development of tunnel magnetoresistance effect through so called giant magnetoresistance effect is explained.

  3. Influence of neutron irradiation on ferromagnetic metallic glasses

    International Nuclear Information System (INIS)

    Miglierini, M.; Nasu, Saburo; Sitek, J.

    1992-01-01

    Transmission 57 Fe Moessbauer spectroscopy is used to study effects of neutron irradiation on magnetic properties of Fe-based ferromagnetic metallic glasses. Elastic stress centers are produced during the process of neutron irradiation as a result of atom mixing. Rearrangement of the atoms causes changes in the average value of the hyperfine field distribution and orientation of the net magnetic moment. They are shown to depend on the composition of the investigated samples. Cr-doped metallic glasses depict transformation from ferromagnetic to paramagnetic state at room temperature after neutron irradiation implying changes in the Curie temperature. Presence of Ni in the samples reduces the effects of radiation damage. (orig.)

  4. Nitrogen induced ferromagnetism in Cobalt doped BaTiO3

    Directory of Open Access Journals (Sweden)

    Chandrima Mitra

    2012-09-01

    Full Text Available The electronic structure and magnetism of Cobalt doped BaTiO3 (BaTi1−xCoxO3 is investigated. Substitutional Nitrogen on an Oxygen site is found to play an important role in inducing net magnetic moments in the system. The presence of a Nitrogen atom as nearest neighbour to a Cobalt atom is crucial in producing spin splitting of both the Nitrogen and Cobalt states thereby introducing a net local magnetic moment. The introduction of Nitrogen is further found to enhance ferromagnetic interactions between Cobalt atoms.

  5. Study Of Higher Moments Of Net-Electric Charge & Net-Proton Number Fluctuations In Pb+Pb Collisions At $\\sqrt{s_{NN}}$=2.76 TeV In ALICE At LHC

    CERN Document Server

    Behera, Nirbhay Kumar

    Lattice QCD predicts that at extreme temperature and energy density, QCD matter will undergo a phase transition from hadronic matter to partonic matter called as QGP. One of the fundamental goals of heavy ion collision experiments to map the QCD phase diagram as a function of temperature (T) and baryo-chemical potential ($\\mu_{B}$). There are many proposed experimental signatures of QGP and fluctuations study are regarded as sensitive tool for it. It is proposed that fluctuation of conserved quantities like net-charge and net-proton can be used to map the QCD phase diagram. The mean ($\\mu$), sigma ($\\sigma$), skewness (S) and kurtosis ($\\kappa$) of the distribution of net charge and net proton are believed to be sensitive probes in fluctuation analysis. It has been argued that critical phenomena are signaled with increase and divergence of correlation length. The dependence of $n^{th}$ order higher moments (cumulants, $c_{n}$) with the correlation length $\\xi$ is as $c_{n}\\sim\\xi^{2.5n-3}$. At LHC energy, the...

  6. Fe-Vacancy-Induced Ferromagnetism in Tetragonal FeSe Thin Films

    International Nuclear Information System (INIS)

    Yong-Feng, Li; Gui-Bin, Liu; Li-Jie, Shi; Bang-Gui, Liu

    2009-01-01

    Motivated by recent experiments, we investigate structural, electronic, and magnetic properties of tetragonal FeSe with Fe vacancies using the state-of-the-art first-principles method. We show that Fe vacancies tend to stay in the same one of the two sublattices and thus induce ferromagnetism in the ground-state phase. Our calculated net moment is in good agreement with the experimental data available. Therefore, the ferromagnetism observed in tetragonal FeSe thin films is explained. It could be made controllable soon for spintronic applications

  7. Local moment formation and magnetic coupling of Mn dopants in Bi2Se3: A low-temperature ferromagnetic resonance study

    Science.gov (United States)

    Savchenko, D.; Tarasenko, R.; Vališka, M.; Kopeček, J.; Fekete, L.; Carva, K.; Holý, V.; Springholz, G.; Sechovský, V.; Honolka, J.

    2018-05-01

    We compare the magnetic and electronic configuration of single Mn atoms in molecular beam epitaxy (MBE) grown Bi2Se3 thin films, focusing on electron paramagnetic (ferromagnetic) resonance (EPR and FMR, respectively) and superconducting quantum interference device (SQUID) techniques. X-ray diffraction (XRD) and electron backscatter diffraction (EBSD) reveal the expected increase of disorder with increasing concentration of magnetic guest atoms, however, Kikuchi patterns show that disorder consists majorly of μm-scale 60° twin domains in the hexagonal Bi2Se3 structure, which are promoted by the presence of single unclustered Mn impurities. Ferromagnetism below TC (5.4±0.3) K can be well described by critical scaling laws M (T) (1 - T /TC) β with a critical exponent β = (0.34 ± 0.2) , suggesting 3D Heisenberg class magnetism instead of e.g. 2D-type coupling between Mn-spins in van der Waals gap sites. From EPR hyperfine structure data we determine a Mn2+ (d5, S = 5/2) electronic configuration with a g-factor of 2.002 for -1/2 → +1/2 transitions. In addition, from the strong dependence of the low temperature FMR fields and linewidth on the field strength and orientation with respect to the Bi2Se3 (0001) plane, we derive magnetic anisotropy energies of up to K1 = -3720 erg/cm3 in MBE-grown Mn-doped Bi2Se3, reflecting the first order magneto-crystalline anisotropy of an in-plane magnetic easy plane in a hexagonal (0001) crystal symmetry. We observe an increase of K1 with increasing Mn concentration, which we interpret to be correlated to a Mn-induced in-plane lattice contraction. Across the ferromagnetic-paramagnetic transition the FMR intensity is suppressed and resonance fields converge the paramagnetic limit of Mn2+ (d5, S = 5/2).

  8. Molecular ferromagnetism

    International Nuclear Information System (INIS)

    Epstein, A.J.

    1990-01-01

    This past year has been one of substantial advancement in both the physics and chemistry of molecular and polymeric ferromagnets. The specific heat studies of (DMeFc)(TCNE) have revealed a cusp at the three-dimensional ferromagnetic transition temperature with a crossover to primarily 1-D behavior at higher temperatures. This paper discusses these studies

  9. Room temperature ferromagnetism with large magnetic moment at low field in rare-earth-doped BiFeO₃ thin films.

    Science.gov (United States)

    Kim, Tae-Young; Hong, Nguyen Hoa; Sugawara, T; Raghavender, A T; Kurisu, M

    2013-05-22

    Thin films of rare earth (RE)-doped BiFeO3 (where RE=Sm, Ho, Pr and Nd) were grown on LaAlO3 substrates by using the pulsed laser deposition technique. All the films show a single phase of rhombohedral structure with space group R3c. The saturated magnetization in the Ho- and Sm-doped films is much larger than the values reported in the literature, and is observed at quite a low field of 0.2 T. For Ho and Sm doping, the magnetization increases as the film becomes thinner, suggesting that the observed magnetism is mostly due to a surface effect. In the case of Nd doping, even though the thin film has a large magnetic moment, the mechanism seems to be different.

  10. Vacancy complexes induce long-range ferromagnetism in GaN

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhenkui; Schwingenschlögl, Udo, E-mail: Udo.Schwingenschlogl@kaust.edu.sa, E-mail: Iman.Roqan@kaust.edu.sa; Roqan, Iman S., E-mail: Udo.Schwingenschlogl@kaust.edu.sa, E-mail: Iman.Roqan@kaust.edu.sa [Physical Sciences and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia)

    2014-11-14

    By means of density functional theory, we argue that ferromagnetism in GaN can be induced by vacancy complexes. Spin polarization originates from the charge compensation between neutral N and Ga vacancies. Defect formation energy calculations predict that a vacancy complex of two positively charged N vacancies and one doubly negative Ga vacancy is likely to form. This defect complex induces a net moment of 1 μ{sub B}, which is localized around the negative Ga center and exhibits pronounced in-plane ferromagnetic coupling. In contrast to simple Ga vacancy induced ferromagnetism, the proposed picture is in line with the fact that N vacancies have a low formation energy. Formation energies indicate mutual stabilization of the intrinsic defects in GaN.

  11. Vacancy complexes induce long-range ferromagnetism in GaN

    KAUST Repository

    Zhang, Zhenkui; Schwingenschlö gl, Udo; Roqan, Iman S.

    2014-01-01

    By means of density functional theory, we argue that ferromagnetism in GaN can be induced by vacancy complexes. Spin polarization originates from the charge compensation between neutral N and Ga vacancies. Defect formation energy calculations predict that a vacancy complex of two positively charged N vacancies and one doubly negative Ga vacancy is likely to form. This defect complex induces a net moment of 1 μB, which is localized around the negative Ga center and exhibits pronounced in-plane ferromagnetic coupling. In contrast to simple Ga vacancy induced ferromagnetism, the proposed picture is in line with the fact that N vacancies have a low formation energy. Formation energies indicate mutual stabilization of the intrinsic defects in GaN.

  12. Vacancy complexes induce long-range ferromagnetism in GaN

    KAUST Repository

    Zhang, Zhenkui

    2014-11-14

    By means of density functional theory, we argue that ferromagnetism in GaN can be induced by vacancy complexes. Spin polarization originates from the charge compensation between neutral N and Ga vacancies. Defect formation energy calculations predict that a vacancy complex of two positively charged N vacancies and one doubly negative Ga vacancy is likely to form. This defect complex induces a net moment of 1 μB, which is localized around the negative Ga center and exhibits pronounced in-plane ferromagnetic coupling. In contrast to simple Ga vacancy induced ferromagnetism, the proposed picture is in line with the fact that N vacancies have a low formation energy. Formation energies indicate mutual stabilization of the intrinsic defects in GaN.

  13. Neutron irradiation effects on magnetic properties of Fe-based ferromagnetic metallic glasses

    International Nuclear Information System (INIS)

    Miglierini, M.; Nasu, Saburo; Skorvanek, I.; Sitek, J.

    1992-01-01

    Transmission 57 Fe Moessbauer spectroscopy, J-H quasistatic hysteresis loop and AC susceptibility measurements are used to study effects of neutron irradiation on magnetic properties of Fe-based-ferromagnetic metallic glasses. Elastic stress centers are produced during the process of neutron irradiation as a result of atom mixing. Rearrangement of the atoms causes changes in the average value of the hyperfine field distribution and orientation of the net magnetic moment. They are shown to depend on the composition of the investigated samples. Cr-doped metallic glasses depict transition from the ferromagnetic to paramagnetic state at room temperature after neutron irradiation implying changes in the Curie temperature. The presence of Ni in the samples reduces the effects of radiation damage as revealed also from position lifetime data. Possible sources of a radiation damage are discussed using the results of γ-ray spectroscopy. (author)

  14. Neutron irradiation effects on magnetic properties of Fe-based ferromagnetic metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Miglierini, M.; Nasu, Saburo (Osaka Univ., Toyonaka (Japan). Faculty of Science); Skorvanek, I.; Sitek, J.

    1992-04-01

    Transmission {sup 57}Fe Moessbauer spectroscopy, J-H quasistatic hysteresis loop and AC susceptibility measurements are used to study effects of neutron irradiation on magnetic properties of Fe-based-ferromagnetic metallic glasses. Elastic stress centers are produced during the process of neutron irradiation as a result of atom mixing. Rearrangement of the atoms causes changes in the average value of the hyperfine field distribution and orientation of the net magnetic moment. They are shown to depend on the composition of the investigated samples. Cr-doped metallic glasses depict transition from the ferromagnetic to paramagnetic state at room temperature after neutron irradiation implying changes in the Curie temperature. The presence of Ni in the samples reduces the effects of radiation damage as revealed also from position lifetime data. Possible sources of a radiation damage are discussed using the results of {gamma}-ray spectroscopy. (author).

  15. Nuclear moments

    CERN Document Server

    Kopferman, H; Massey, H S W

    1958-01-01

    Nuclear Moments focuses on the processes, methodologies, reactions, and transformations of molecules and atoms, including magnetic resonance and nuclear moments. The book first offers information on nuclear moments in free atoms and molecules, including theoretical foundations of hyperfine structure, isotope shift, spectra of diatomic molecules, and vector model of molecules. The manuscript then takes a look at nuclear moments in liquids and crystals. Discussions focus on nuclear paramagnetic and magnetic resonance and nuclear quadrupole resonance. The text discusses nuclear moments and nucl

  16. Ferromagnetic nanorings

    International Nuclear Information System (INIS)

    Vaz, C A F; Hayward, T J; Llandro, J; Schackert, F; Morecroft, D; Bland, J A C; Klaeui, M; Laufenberg, M; Backes, D; Ruediger, U; Castano, F J; Ross, C A; Heyderman, L J; Nolting, F; Locatelli, A; Faini, G; Cherifi, S; Wernsdorfer, W

    2007-01-01

    Ferromagnetic metal rings of nanometre range widths and thicknesses exhibit fundamentally new spin states, switching behaviour and spin dynamics, which can be precisely controlled via geometry, material composition and applied field. Following the discovery of the 'onion state', which mediates the switching to and between vortex states, a range of fascinating phenomena has been found in these structures. In this overview of our work on ring elements, we first show how the geometric parameters of ring elements determine the exact equilibrium spin configuration of the domain walls of rings in the onion state, and we show how such behaviour can be understood as the result of the competition between the exchange and magnetostatic energy terms. Electron transport provides an extremely sensitive probe of the presence, spatial location and motion of domain walls, which determine the magnetic state in individual rings, while magneto-optical measurements with high spatial resolution can be used to probe the switching behaviour of ring structures with very high sensitivity. We illustrate how the ring geometry has been used for the study of a wide variety of magnetic phenomena, including the displacement of domain walls by electric currents, magnetoresistance, the strength of the pinning potential introduced by nanometre size constrictions, the effect of thermal excitations on the equilibrium state and the stochastic nature of switching events

  17. Anomalous spin distribution in the superconducting ferromagnet UCoGe studied by polarized neutron diffraction

    NARCIS (Netherlands)

    Prokeš, K.; de Visser, A.; Huang, Y.K.; Fåk, B.; Ressouche, E.

    2010-01-01

    We report a polarized neutron-diffraction study conducted to reveal the nature of the weak ferromagnetic moment in the superconducting ferromagnet UCoGe. We find that the ordered moment in the normal phase in low magnetic fields (B∥c) is predominantly located at the U atom and has a magnitude of

  18. Ferromagnetic Swimmers - Devices and Applications

    Science.gov (United States)

    Hamilton, Joshua; Petrov, Peter; Winlove, C. Peter; Gilbert, Andrew; Bryan, Matthew; Ogrin, Feodor

    2017-11-01

    Microscopic swimming devices hold promise for radically new applications in lab-on-a-chip and microfluidic technology, diagnostics and drug delivery etc. We propose a new class of autonomous ferromagnetic swimming devices, actuated and controlled solely by an oscillating magnetic field. Experimentally, these devices (3.6 mm) are based on a pair of interacting ferromagnetic particles of different size and different anisotropic properties joined by an elastic link and actuated by an external time-dependent magnetic field. The net motion is generated through a combination of dipolar interparticle gradient forces, time-dependent torque and hydrodynamic coupling. We investigate the dynamic performance of a prototype (3.6 mm) of the ferromagnetic swimmer in fluids of different viscosity as a function of the external field parameters and demonstrate stable propulsion over a wide range of Reynolds numbers. Manipulation of the external magnetic field resulted in robust control over the speed and direction of propulsion. We also demonstrate our ferromagnetic swimmer working as a macroscopic prototype of a microfluidic pump. By physically tethering the swimmer, instead of swimming, the swimmer generates a directional flow of liquid around itself.

  19. Novel room temperature ferromagnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Gupta, Amita [KTH Royal Inst. of Technology, Stockholm (Sweden)

    2004-06-01

    distribution of Mn substituting for Zn a 2+ state in the ZnO lattice. Ferromagnetic Resonance (FMR) technique is used to confirm the existence of ferromagnetic ordering at temperatures as high as 425K. The ab initio calculations were found to be consistent with the observation of ferromagnetism arising from fully polarized Mn 2+ state. The key to observed room temperature ferromagnetism in this system is the low temperature processing, which prevents formation of clusters, secondary phases and the host ZnO from becoming n-type. The electronic structure of the same Mn doped ZnO thin films studied using XAS, XES and RIXS, revealed a strong hybridization between Mn 3d and O 2p states, which is an important characteristic of a Dilute magnetic Semiconductor (DMS). It is shown that the various processing conditions like sintering temperature, dopant concentration and the properties of precursors used for making of DMS have a great influence on the final properties. Use of various experimental techniques to verify the physical properties, and to understand the mechanism involved to give rise to ferromagnetism is presented. Methods to improve the magnetic moment in Mn doped ZnO are also described. New promising DMS materials (such as Cu doped ZnO are explored). The demonstrated new capability to fabricate powder, pellets, and thin films of room temperature ferromagnetic semiconductors thus makes possible the realization of a wide range of complex elements for a variety of new multifunctional phenomena related to Spintronic devices as well as magneto-optic components.

  20. Enhanced moments in bcc Co{sub 1−x}Mn{sub x} on MgO(001)

    Energy Technology Data Exchange (ETDEWEB)

    Snow, R.J.; Bhatkar, H. [Department of Physics, Montana State University, Bozeman, MT 59715 (United States); N' Diaye, A.T.; Arenholz, E. [Advanced Light Source, Lawrence Berkeley Nat. Labs, Berkeley, CA 94720 (United States); Idzerda, Y.U., E-mail: Idzerda@montana.edu [Department of Physics, Montana State University, Bozeman, MT 59715 (United States)

    2016-12-01

    A 40% enhancement of the Co magnetic moment has been found for thin films of bcc Co{sub 1−x}Mn{sub x} grown by molecular beam epitaxy on a 2 nm bcc Fe buffer layer on MgO(001). Although the bcc phase cannot be stabilized in the bulk, we confirm that it is stable as an epitaxial film in the composition range x=0–0.7. Using X-ray absorption spectroscopy and X-ray magnetic circular dichroism, we show that the Co moment is a maximum of 2.38 μ{sub B} at x=0.24, while the net Mn moment remains roughly constant until x=0.24, then drops steadily. Mn is found to align parallel with Co for all ferromagnetic concentrations, up to x=0.7, where the total moment of the film abruptly collapses to zero, most likely due to the onset of the observed structural instability. - Highlights: • Stabilization of bcc Co{sub 1−x}Mn{sub x} films in the composition range of x=0 to 0.7. • Enhancement of Co moment by 40% from pure bcc Co. • Parallel alignment of Mn moment and Co moment. • Measured the elemental moment of Co and Mn as a function of composition.

  1. Angle and temperature dependence of the magnetocrystalline anisotropy energy and the microscopic magnetic moments of the ferromagnetic semi-metal CrO{sub 2}; Winkel- und Temperaturabhaengigkeit der magnetokristallinen Anisotropieenergie und der mikroskopischen magnetischen Momente des ferromagnetischen Halbmetalls CrO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Gold, S.

    2005-07-01

    The aim of this work was to examine, by use of XMCD-effect and additional measurements with SQUID-magnetometer, spin moments and hysteresis loops, but also to clarify the intrinsic properties like magnetocrystalline anisotropy, magnetic dipole term, and the nearly quenched orbital moment. The XMCD-measurements were done at the Cr L{sub 2,3}- and the O K-edge. The results for CrO{sub 2} show a strong dependence of the orbital, the sum of spin moment and magnetic dipole term, and the magnetocrystalline anisotropy energy from the angle between rutile a- and c-axis. Even more than the complete orbital moment, two separable and different spectral features show strong alterations of the different orbital moments. In a second part of this work the temperature dependence was investigated. The aim was to clarify the origin of the orbital moment, dipole term, and MAE in dependence of the spin moment and compare the results to different theoretical models. The extracted orbital moments and the magnetic dipole term show the same temperature dependence as the spin moment. In the following a dependence of the squared measured spin moment could be found for the MAE. For the first time the magnetic dipole term could be identified as the reason of the magnetocrystalline anisotropy energy. A strong Cr-O hybridisation was found, which shows in a similar structure and temperature dependence of the orbital moments for Cr L{sub 2,3} and the XMCD effect at O-K edge. (orig.)

  2. Carrier concentration induced ferromagnetism in semiconductors

    International Nuclear Information System (INIS)

    Story, T.

    2007-01-01

    In semiconductor spintronics the key materials issue concerns ferromagnetic semiconductors that would, in particular, permit an integration (in a single multilayer heterostructure) of standard electronic functions of semiconductors with magnetic memory function. Although classical semiconductor materials, such as Si or GaAs, are nonmagnetic, upon substitutional incorporation of magnetic ions (typically of a few atomic percents of Mn 2+ ions) and very heavy doping with conducting carriers (at the level of 10 20 - 10 21 cm -3 ) a ferromagnetic transition can be induced in such diluted magnetic semiconductors (also known as semimagnetic semiconductors). In the lecture the spectacular experimental observations of carrier concentration induced ferromagnetism will be discussed for three model semiconductor crystals. p - Ga 1-x Mn x As currently the most actively studied and most perspective ferromagnetic semiconductor of III-V group, in which ferromagnetism appears due to Mn ions providing both local magnetic moments and acting as acceptor centers. p - Sn 1-x Mn x Te and p - Ge 1-x Mn x Te classical diluted magnetic semiconductors of IV-VI group, in which paramagnet-ferromagnet and ferromagnet-spin glass transitions are found for very high hole concentration. n - Eu 1-x Gd x Te mixed magnetic crystals, in which the substitution of Gd 3+ ions for Eu 2+ ions creates very high electron concentration and transforms antiferromagnetic EuTe (insulating compound) into ferromagnetic n-type semiconductor alloy. For each of these materials systems the key physical features will be discussed concerning: local magnetic moments formation, magnetic phase diagram as a function of magnetic ions and carrier concentration as well as Curie temperature and magnetic anisotropy engineering. Various theoretical models proposed to explain the effect of carrier concentration induced ferromagnetism in semiconductors will be briefly discussed involving mean field approaches based on Zener and RKKY

  3. Theoretical study on the magnetic moments formation in Ta-doped anatase TiO2

    Science.gov (United States)

    Bupu, A.; Majidi, M. A.; Rusydi, A.

    2017-04-01

    We present a theoretical study on Ti-vacancy induced ferromagnetism in Ta-doped anatase TiO2. Experimental study of Ti1-x Ta x O2 thin film has shown that Ti-vacancies (assisted by Ta doping) induce the formation of localized magnetic moment around it, then, the observed ferromagnetism is caused by the alignment of localized magnetic moments through Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. In this study, we focus on the formation of the localized magnetic moments in this system. We hypothesize that on a unit cell, Ti-vacancy has caused four electrons from the surrounding oxygen atoms to become unpaired. These unpaired electrons then arrange themselves into a configuration with a non-zero net magnetic moment. To examine our hypothesis, we construct a Hamiltonian of the four unpaired electrons, incorporating the Coulomb intra- and inter-orbital interactions, in matrix form. Using a set of chosen parameter values, we diagonalize the Hamiltonian to get the eigenstates and eigenvalues, then, with the resulting eigenstates, we calculate the magnetic moment, μ, by obtaining the expectation value of the square of total spin operator. Our calculation results show that in the ground state, provided that the ratio of parameters satisfies some criterion, μ ≈ 4μ B , corresponding to the four electron spins being almost perfectly aligned, can be achieved. Further, as long as we keep the Coulomb intra-orbital interaction between 0.5 and 1 eV, we find that μ ≈ 4μ B is robust up to far above room temperature. Our results demonstrate that Ti vacancies in anatase TiO2 can form very stable localized magnetic moments.

  4. A phenomenological approach to study the effect of uniaxial anisotropy on the magnetization of ferromagnetic nanoparticles

    Science.gov (United States)

    Sánchez-Marín, N.; Cuchillo, A.; Knobel, M.; Vargas, P.

    2018-04-01

    We study the effect of the uniaxial anisotropy in a system of ideal, noninteracting ferromagnetic nanoparticles by means of a thermodynamical model. We show that the effect of the anisotropy can be easily assimilated in a temperature shift Ta∗, in analogy to what was proposed by Allia et al. (2001) in the case of interacting nanomagnets. The phenomenological anisotropic Ta∗ parameter can be negative, indicating an antiferromagnetic-like behavior, or positive, indicating a ferromagnetic-like character as seen in the inverse susceptibility behavior as a function of temperature. The study is done considering an easy axis distribution to take into account the anisotropy axis dispersion in real samples (texture). In the case of a volumetric uniform distribution of anisotropy axes, the net effect makes Ta∗ to vanish, and the magnetic susceptibility behaves like a conventional superparamagnetic system, whereas in the others a finite value is obtained for Ta∗ . When magnetic moment distribution is considered, the effect is to enhance the Ta∗ parameter, when the dispersion of the magnetic moments becomes wider.

  5. Pressure-induced weak ferromagnetism in uranium dioxide, UO2

    International Nuclear Information System (INIS)

    Sakai, H; Kato, H; Tokunaga, Y; Kambe, S; Walstedt, R E; Nakamura, A; Tateiwa, N; Kobayashi, T C

    2003-01-01

    The dc magnetization of insulating UO 2 under high pressure up to ∼1 GPa has been measured using a piston-cylinder cell. Pressure-induced weak ferromagnetism appeared at low pressure (∼0.2 GPa). Both the remanent magnetization and the coercive force increase as pressure increases. This weak ferromagnetism may come from spin canting or from uncompensated moments around grain boundaries

  6. Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

    Science.gov (United States)

    Pasanai, K.

    2017-01-01

    A theory of tunneling spectroscopy of ferromagnet/ferromagnet/ferromagnet junctions was studied. We applied a delta-functional approximation for the interface scattering properties under a one-dimensional system of a free electron approach. The reflection and transmission probabilities were calculated in the ballistic regime, and the conductance spectra were then calculated using the Landauer formulation. The magnetization directions were set to be either parallel (P) or anti-parallel (AP) alignments, for comparison. We found that the conductance spectra was suppressed when increasing the interfacial scattering at the interfaces. Moreover, the electron could exhibit direct transmission when the thickness was rather thin. Thus, there was no oscillation in this case. However, in the case of a thick layer the conductance spectra oscillated, and this oscillation was most prominent when the middle layer thickness increased. In the case of direct transmission, the conductance spectra of P and AP systems were definitely suppressed with increased exchange energy of the middle ferromagnet. This also refers to an increase in the magnetoresistance of the junction. In the case of oscillatory behavior, the positions of the resonance peaks were changed as the exchange energy was changed.

  7. Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

    Energy Technology Data Exchange (ETDEWEB)

    Pasanai, K., E-mail: krisakronmsu@gmail.com

    2017-01-15

    A theory of tunneling spectroscopy of ferromagnet/ferromagnet/ferromagnet junctions was studied. We applied a delta-functional approximation for the interface scattering properties under a one-dimensional system of a free electron approach. The reflection and transmission probabilities were calculated in the ballistic regime, and the conductance spectra were then calculated using the Landauer formulation. The magnetization directions were set to be either parallel (P) or anti-parallel (AP) alignments, for comparison. We found that the conductance spectra was suppressed when increasing the interfacial scattering at the interfaces. Moreover, the electron could exhibit direct transmission when the thickness was rather thin. Thus, there was no oscillation in this case. However, in the case of a thick layer the conductance spectra oscillated, and this oscillation was most prominent when the middle layer thickness increased. In the case of direct transmission, the conductance spectra of P and AP systems were definitely suppressed with increased exchange energy of the middle ferromagnet. This also refers to an increase in the magnetoresistance of the junction. In the case of oscillatory behavior, the positions of the resonance peaks were changed as the exchange energy was changed. - Highlights: • The conductance spectra of a FM/FM/FM junction were calculated. • The conductance spectra were suppressed by the exchange energy. • The exchange energy and the potential strength play similar roles in the junctions.

  8. Conductance spectra of asymmetric ferromagnet/ferromagnet/ferromagnet junctions

    International Nuclear Information System (INIS)

    Pasanai, K.

    2017-01-01

    A theory of tunneling spectroscopy of ferromagnet/ferromagnet/ferromagnet junctions was studied. We applied a delta-functional approximation for the interface scattering properties under a one-dimensional system of a free electron approach. The reflection and transmission probabilities were calculated in the ballistic regime, and the conductance spectra were then calculated using the Landauer formulation. The magnetization directions were set to be either parallel (P) or anti-parallel (AP) alignments, for comparison. We found that the conductance spectra was suppressed when increasing the interfacial scattering at the interfaces. Moreover, the electron could exhibit direct transmission when the thickness was rather thin. Thus, there was no oscillation in this case. However, in the case of a thick layer the conductance spectra oscillated, and this oscillation was most prominent when the middle layer thickness increased. In the case of direct transmission, the conductance spectra of P and AP systems were definitely suppressed with increased exchange energy of the middle ferromagnet. This also refers to an increase in the magnetoresistance of the junction. In the case of oscillatory behavior, the positions of the resonance peaks were changed as the exchange energy was changed. - Highlights: • The conductance spectra of a FM/FM/FM junction were calculated. • The conductance spectra were suppressed by the exchange energy. • The exchange energy and the potential strength play similar roles in the junctions.

  9. Study of coexistence of ferromagnetism and superconductivity in single-crystal ErRh4B4

    International Nuclear Information System (INIS)

    Sinha, S.K.; Crabtree, G.W.; Hinks, D.G.; Mook, H.

    1981-01-01

    Neutron diffraction and resistivity measurements on single crystals of ErRh 4 B 4 have revealed that both superconductivity and ferromagnetic order coexist in this material between 0.71 and 1.2 0 K. In this intermediate phase, a linear polarized modulated structure with a wavelength of approximately 100 A is observed. The modulated moment increases faster than the ferromagnetic moment down to 0.71 K and then disappears suddenly, with loss of superconductivity and a transition to a normal ferromagnetic state. This transition is accompanied by temperature hysteresis of about 60 mK. The same hysteresis, in the inverse sense, is exhibited by the ferromagnetic component. We interpret the intermediate phase as being one of coexisting normal ferromagnetic domains and superconducting sinusoidally ordered domains. Evidence of a small percentage of small ferromagnetic regions of size approx. 100 A is also seen in both the intermediate and ferromagnetic phases. 3 figures

  10. The Kondo effect in ferromagnetic atomic contacts.

    Science.gov (United States)

    Calvo, M Reyes; Fernández-Rossier, Joaquín; Palacios, Juan José; Jacob, David; Natelson, Douglas; Untiedt, Carlos

    2009-04-30

    Iron, cobalt and nickel are archetypal ferromagnetic metals. In bulk, electronic conduction in these materials takes place mainly through the s and p electrons, whereas the magnetic moments are mostly in the narrow d-electron bands, where they tend to align. This general picture may change at the nanoscale because electrons at the surfaces of materials experience interactions that differ from those in the bulk. Here we show direct evidence for such changes: electronic transport in atomic-scale contacts of pure ferromagnets (iron, cobalt and nickel), despite their strong bulk ferromagnetism, unexpectedly reveal Kondo physics, that is, the screening of local magnetic moments by the conduction electrons below a characteristic temperature. The Kondo effect creates a sharp resonance at the Fermi energy, affecting the electrical properties of the system; this appears as a Fano-Kondo resonance in the conductance characteristics as observed in other artificial nanostructures. The study of hundreds of contacts shows material-dependent log-normal distributions of the resonance width that arise naturally from Kondo theory. These resonances broaden and disappear with increasing temperature, also as in standard Kondo systems. Our observations, supported by calculations, imply that coordination changes can significantly modify magnetism at the nanoscale. Therefore, in addition to standard micromagnetic physics, strong electronic correlations along with atomic-scale geometry need to be considered when investigating the magnetic properties of magnetic nanostructures.

  11. Room-temperature ferromagnetism in hydrogenated ZnO nanoparticles

    International Nuclear Information System (INIS)

    Xue, Xudong; Liu, Liangliang; Wang, Zhu; Wu, Yichu

    2014-01-01

    The effect of hydrogen doping on the magnetic properties of ZnO nanoparticles was investigated. Hydrogen was incorporated by annealing under 5% H 2 in Ar ambient at 700 °C. Room-temperature ferromagnetism was induced in hydrogenated ZnO nanoparticles, and the observed ferromagnetism could be switched between “on” and “off” states through hydrogen annealing and oxygen annealing process, respectively. It was found that Zn vacancy and OH bonding complex (V Zn  + OH) was crucial to the observed ferromagnetism by using the X-ray photoelectron spectroscopy and positron annihilation spectroscopy analysis. Based on first-principles calculations, V Zn  + OH was favorable to be presented due to the low formation energy. Meanwhile, this configuration could lead to a magnetic moment of 0.57 μ B . The Raman and photoluminescence measurements excluded the possibility of oxygen vacancy as the origin of the ferromagnetism

  12. Room-temperature ferromagnetism in hydrogenated ZnO nanoparticles

    Science.gov (United States)

    Xue, Xudong; Liu, Liangliang; Wang, Zhu; Wu, Yichu

    2014-01-01

    The effect of hydrogen doping on the magnetic properties of ZnO nanoparticles was investigated. Hydrogen was incorporated by annealing under 5% H2 in Ar ambient at 700 °C. Room-temperature ferromagnetism was induced in hydrogenated ZnO nanoparticles, and the observed ferromagnetism could be switched between "on" and "off" states through hydrogen annealing and oxygen annealing process, respectively. It was found that Zn vacancy and OH bonding complex (VZn + OH) was crucial to the observed ferromagnetism by using the X-ray photoelectron spectroscopy and positron annihilation spectroscopy analysis. Based on first-principles calculations, VZn + OH was favorable to be presented due to the low formation energy. Meanwhile, this configuration could lead to a magnetic moment of 0.57 μB. The Raman and photoluminescence measurements excluded the possibility of oxygen vacancy as the origin of the ferromagnetism.

  13. Strain-Induced Ferromagnetism in Antiferromagnetic LuMnO3 Thin Films

    Science.gov (United States)

    White, J. S.; Bator, M.; Hu, Y.; Luetkens, H.; Stahn, J.; Capelli, S.; Das, S.; Döbeli, M.; Lippert, Th.; Malik, V. K.; Martynczuk, J.; Wokaun, A.; Kenzelmann, M.; Niedermayer, Ch.; Schneider, C. W.

    2013-07-01

    Single phase and strained LuMnO3 thin films are discovered to display coexisting ferromagnetic and antiferromagnetic orders. A large moment ferromagnetism (≈1μB), which is absent in bulk samples, is shown to display a magnetic moment distribution that is peaked at the highly strained substrate-film interface. We further show that the strain-induced ferromagnetism and the antiferromagnetic order are coupled via an exchange field, therefore demonstrating strained rare-earth manganite thin films as promising candidate systems for new multifunctional devices.

  14. Temperature dependence of spin and orbital magnetic moments of Sm 4f electrons in (Sm, Gd)Al2

    International Nuclear Information System (INIS)

    Qiao, S.; Kimura, A.; Adachi, H.; Iori, K.; Miyamoto, K.; Xie, T.; Namatame, H.; Taniguchi, M.; Tanaka, A.; Muro, T.; Imada, S.; Suga, S.

    2005-01-01

    X-ray magnetic circular dichroism studies were carried out on (Sm, Gd)Al 2 , a ferromagnet without net magnetization at a certain compensation temperature. For Sm 4f electrons, the following understandings were obtained: the magnitude of expectation value of orbital magnetic moment (m L Sm ) is always larger than that of spin one (m S Sm ), so the cancellation of total spin and orbital magnetic moments cannot be achieved only by Sm 4f electrons and the contributions from Gd ions and conduction electrons are important; when the temperature decreases, the magnitude of both m L Sm and m S Sm increases and the gross magnetic moment due to the Sm 4f electrons monotonically deviates from zero. These results tell us that the temperature dependence of magnetic moments related with the electrons other than Sm 4f ones may play important roles in the subtle adjustment of the total spin and orbital magnetic moments to the zero magnetization at the compensation temperature

  15. Itinerant ferromagnetism in the narrow band limit

    CERN Document Server

    Liu, S H

    2000-01-01

    It is shown that in the narrow band, strong interaction limit the paramagnetic state of an itinerant ferromagnet is described by the disordered local moment state. As a result, the Curie temperature is orders of magnitude lower than what is expected from the large exchange splitting of the spin bands. An approximate analysis has also been carried out for the partially ordered state, and the result explains the temperature evolvement of the magnetic contributions to the resistivity and low-energy optical conductivity of CrO sub 2.

  16. Multipole electromagnetic moments of neutrino in dispersive medium

    International Nuclear Information System (INIS)

    Semikov, V.B.; Smorodinskij, Ya.A.; Gosudarstvennyj Komitet po Ispol'zovaniyu Atomnoj Ehnergii SSSR, Moscow

    1989-01-01

    Four multipole moments for a Dirac and Majorana neutrino in a dispersive medium are calculated viz., the electric monopole (charge), electric dipole, magnetic dipole and anapole dipole moment. For comparison the same quantities are presented in the case of vacuum. The neutrino does not possess an (induced) anapole moment in an isotropic medium; however, in a ferromagnetic such a moment exists and for the Majorana neutrino it is the only electromagnetic cjaracteristic. As an example the cross section for elastic scattering of a Majorana neutrino by nuclei in an isotropic plasma is calculated

  17. Competing ferromagnetic and anti-ferromagnetic interactions in iron nitride ζ-Fe2N

    Science.gov (United States)

    Rao, K. Sandeep; Salunke, H. G.

    2018-03-01

    The paper discusses the magnetic state of zeta phase of iron nitride viz. ζ-Fe2N on the basis of spin polarized first principles electronic structure calculations together with a review of already published data. Results of our first principles study suggest that the ground state of ζ-Fe2N is ferromagnetic (FM) with a magnetic moment of 1.528μB on the Fe site. The FM ground state is lower than the anti-ferromagnetic (AFM) state by 8.44 meV and non-magnetic (NM) state by 191 meV per formula unit. These results are important in view of reports which claim that ζ-Fe2N undergoes an AFM transition below 10 K and others which do not observe any magnetic transition up to 4.2 K. We argue that the experimental results of AFM transition below 10 K are inconclusive and we propose the presence of competing FM and AFM superexchange interactions between Fe sites mediated by nitrogen atoms, which are consistent with Goodenough-Kanamori-Anderson rules. We find that the anti-ferromagnetically coupled Fe sites are outnumbered by ferromagnetically coupled Fe sites leading to a stable FM ground state. A Stoner analysis of the results also supports our claim of a FM ground state.

  18. Superconducting Ferromagnetic Nanodiamond.

    Science.gov (United States)

    Zhang, Gufei; Samuely, Tomas; Xu, Zheng; Jochum, Johanna K; Volodin, Alexander; Zhou, Shengqiang; May, Paul W; Onufriienko, Oleksandr; Kačmarčík, Jozef; Steele, Julian A; Li, Jun; Vanacken, Johan; Vacík, Jiri; Szabó, Pavol; Yuan, Haifeng; Roeffaers, Maarten B J; Cerbu, Dorin; Samuely, Peter; Hofkens, Johan; Moshchalkov, Victor V

    2017-06-27

    Superconductivity and ferromagnetism are two mutually antagonistic states in condensed matter. Research on the interplay between these two competing orderings sheds light not only on the cause of various quantum phenomena in strongly correlated systems but also on the general mechanism of superconductivity. Here we report on the observation of the electronic entanglement between superconducting and ferromagnetic states in hydrogenated boron-doped nanodiamond films, which have a superconducting transition temperature T c ∼ 3 K and a Curie temperature T Curie > 400 K. In spite of the high T Curie , our nanodiamond films demonstrate a decrease in the temperature dependence of magnetization below 100 K, in correspondence to an increase in the temperature dependence of resistivity. These anomalous magnetic and electrical transport properties reveal the presence of an intriguing precursor phase, in which spin fluctuations intervene as a result of the interplay between the two antagonistic states. Furthermore, the observations of high-temperature ferromagnetism, giant positive magnetoresistance, and anomalous Hall effect bring attention to the potential applications of our superconducting ferromagnetic nanodiamond films in magnetoelectronics, spintronics, and magnetic field sensing.

  19. Unexpected large room-temperature ferromagnetism in porous Cu{sub 2}O thin films

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Xue [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Sun, Huiyuan, E-mail: huiyuansun@126.com [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Liu, Lihu; Jia, Xiaoxuan; Liu, Huiyuan [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China)

    2015-05-15

    Porous Cu{sub 2}O films have been fabricated on porous anodic alumina substrates using DC-reactive magnetron sputtering with pure Cu targets, and unexpectedly large room temperature ferromagnetism has been observed in the films. The maximum saturation magnetic moment along the out-of-plane direction was as high as 94 emu/cm{sup 3}. Photoluminescence spectra show that the ferromagnetism originates with oxygen vacancies. The ferromagnetism could be adjusted by changing the concentration of oxygen vacancies through annealing in an oxygen atmosphere. These observations suggest that the origin of the ferromagnetism is due to coupling between oxygen vacancies with local magnetic moments in the porous Cu{sub 2}O films, which can occur either directly through exchange interactions between oxygen vacancies, or through the mediation of conduction electrons. Such a ferromagnet without the presence of any ferromagnetic dopant may find applications in spintronic devices. - Highlights: • Porous Cu{sub 2}O films were deposited on porous anodic alumina (PAA) substrates. • Significant room-temperature ferromagnetism has been observed in porous Cu{sub 2}O films. • Ferromagnetism of Cu{sub 2}O films exhibited different magnetic signals with the field. • The saturation magnetization is 94 emu/cm{sup 3} with an out-of-plane.

  20. Petri Nets

    Indian Academy of Sciences (India)

    In a computer system, for example, typical discrete events ... This project brought out a series of influential reports on Petri net theory in the mid and late ... Technology became a leading centre for Petri net research and from then on, Petri nets ...

  1. Superconducting Ferromagnetic Nanodiamond

    Czech Academy of Sciences Publication Activity Database

    Zhang, G.; Samuely, T.; Xu, Z.; Jochum, J. K.; Volodin, A.; Zhou, S. Q.; May, P. W.; Onufriienko, O.; Kacmarik, J.; Steele, J. A.; Li, J.; Vanacken, J.; Vacík, Jiří; Szabo, P.; Yuan, H. F.; Roeffaers, M. B. J.; Cerbu, D.; Samuely, P.; Hofkens, J.; Moshchalkov, V.V.

    2017-01-01

    Roč. 11, č. 6 (2017), s. 5358-5366 ISSN 1936-0851 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA MŠk LM2015056 Institutional support: RVO:61389005 Keywords : nanodiamond * superconductivity and ferromagnetism * spin fluctuations * giant positive magnetoresistance * anamalous Hall effect Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders OBOR OECD: Nano-materials (production and properties ) Impact factor: 13.942, year: 2016

  2. Polarized single crystal neutron diffraction study of the zero-magnetization ferromagnet Sm1 -xGdxAl2 (x =0.024 )

    Science.gov (United States)

    Chatterji, T.; Stunault, A.; Brown, P. J.

    2018-02-01

    We have determined the temperature evolution of the spin and orbital moments in the zero-magnetization ferromagnet Sm1 -xGdxAl2 (x = 0.024) by combining polarized and unpolarized single crystal neutron diffraction data. The sensitivity of the polarized neutron technique has allowed the moment values to be determined with a precision of ≈0.1 μB . Our results clearly demonstrate that, when magnetized by a field of 8 T, the spin and orbital moments in Sm1 -xGdxAl2 are oppositely directed, so that the net magnetization is very small. Below 60 K the contributions from spin and orbital motions are both about 2 μB , with that due to orbital motion being slightly larger than that due to spin. Between 60 and 65 K the contributions of each to the magnetization fall rapidly and change sign at Tcomp ≈67 K , above which the aligned moments recover but with the orbital magnetization still slightly higher than the spin one. These results imply that above Tcomp the small resultant magnetization of the Sm3 + ion is oppositely directed to the magnetizing field. It is suggested that this anomaly is due to polarization of conduction electron spin associated with the doping Gd3 + ions.

  3. Graphene-ferromagnet interfaces: hybridization, magnetization and charge transfer.

    Science.gov (United States)

    Abtew, Tesfaye; Shih, Bi-Ching; Banerjee, Sarbajit; Zhang, Peihong

    2013-03-07

    Electronic and magnetic properties of graphene-ferromagnet interfaces are investigated using first-principles electronic structure methods in which a single layer graphene is adsorbed on Ni(111) and Co(111) surfaces. Due to the symmetry matching and orbital overlap, the hybridization between graphene pπ and Ni (or Co) d(z(2)) states is very strong. This pd hybridization, which is both spin and k dependent, greatly affects the electronic and magnetic properties of the interface, resulting in a significantly reduced (by about 20% for Ni and 10% for Co) local magnetic moment of the top ferromagnetic layer at the interface and an induced spin polarization on the graphene layer. The calculated induced magnetic moment on the graphene layer agrees well with a recent experiment. In addition, a substantial charge transfer across the graphene-ferromagnet interfaces is observed. We also investigate the effects of thickness of the ferromagnet slab on the calculated electronic and magnetic properties of the interface. The strength of the pd hybridization and the thickness-dependent interfacial properties may be exploited to design structures with desirable magnetic and transport properties for spintronic applications.

  4. Rise and fall of ferromagnetism in O-irradiated Al2O3 single crystals

    International Nuclear Information System (INIS)

    Li, Qiang; Xu, Juping; Liu, Jiandang; Du, Huaijiang; Ye, Bangjiao

    2015-01-01

    In dilute magnetic semiconductors studies, sapphire was usually used as non-magnetic substrate for films. We observed weak ferromagnetic component in Al 2 O 3 single crystal substrate, and excluded the possibility of ferromagnetic contaminations carefully by inductively coupled plasma mass spectrometry and X-ray photoelectron spectroscopy. The ferromagnetism rise and fall during the process of annealing-oxygen irradiation-annealing of the sapphire. The ferromagnetic changes are consistent with Al-vacancy related defects detected by positron annihilation spectroscopy. With first-principle calculations, we confirm that Al-vacancy can introduce magnetic moment for 3 μB in Al 2 O 3 crystal and form stable V Al -V Al ferromagnetic coupling at room temperature

  5. Room temperature ferromagnetism in Cu doped ZnO

    Science.gov (United States)

    Ali, Nasir; Singh, Budhi; Khan, Zaheer Ahmed; Ghosh, Subhasis

    2018-05-01

    We report the room temperature ferromagnetism in 2% Cu doped ZnO films grown by RF magnetron sputtering in different argon and oxygen partial pressure. X-ray photoelectron spectroscopy was used to ascertain the oxidation states of Cu in ZnO. The presence of defects within Cu-doped ZnO films can be revealed by electron paramagnetic resonance. It has been observed that saturated magnetic moment increase as we increase the zinc vacancies during deposition.

  6. Assembling Transgender Moments

    Science.gov (United States)

    Greteman, Adam J.

    2017-01-01

    In this article, the author seeks to assemble moments--scholarly, popular, and aesthetic--in order to explore the possibilities that emerge as moments collect in education's encounters with the needs, struggles, and possibilities of transgender lives and practices. Assembling moments, the author argues, illustrates the value of "moments"…

  7. Hysteresis in conducting ferromagnets

    International Nuclear Information System (INIS)

    Schneider, Carl S.; Winchell, Stephen D.

    2006-01-01

    Maxwell's magnetic diffusion equation is solved for conducting ferromagnetic cylinders to predict a magnetic wave velocity, a time delay for flux penetration and an eddy current field, one of five fields in the linear unified field model of hysteresis. Measured Faraday voltages for a thin steel toroid are shown to be proportional to magnetic field step amplitude and decrease exponentially in time due to maximum rather than average permeability. Dynamic permeabilities are a field convolution of quasistatic permeability and the delay function from which we derive and observe square root dependence of coercivity on rate of field change

  8. Net Neutrality

    DEFF Research Database (Denmark)

    Savin, Andrej

    2017-01-01

    Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else.......Repealing “net neutrality” in the US will have no bearing on Internet freedom or security there or anywhere else....

  9. Non-conductive ferromagnetic carbon-coated (Co, Ni) metal/polystyrene nanocomposites films

    Energy Technology Data Exchange (ETDEWEB)

    Takacs, H., E-mail: helene.takacs@gmail.com [CEA, LETI, MINATEC Campus, Grenoble 38054 (France); LTM-CNRS-UJF, CEA, LETI, Minatec Campus, Grenoble 38054 (France); Viala, B.; Hermán, V. [CEA, LETI, MINATEC Campus, Grenoble 38054 (France); Tortai, J.-H. [LTM-CNRS-UJF, CEA, LETI, Minatec Campus, Grenoble 38054 (France); Duclairoir, F. [Université Grenoble Alpes, INAC, Grenoble 38054 (France); CEA, INAC, Grenoble 38054 (France)

    2016-03-07

    This article reports non-conductive ferromagnetic properties of metal/polymer nanocomposite films intended to be used for RF applications. The nanocomposite arrangement is unique showing a core double-shell structure of metal-carbon-polystyrene: M/C//P{sub 1}/P{sub 2}, where M = Co, Ni is the core material, C = graphene or carbon is the first shell acting as a protective layer against oxidation, P{sub 1} = pyrene-terminated polystyrene is the second shell for electrical insulation, and P{sub 2} = polystyrene is a supporting matrix (// indicates actual grafting). The nanocomposite formulation is briefly described, and the film deposition by spin-coating is detailed. Original spin-curves are reported and analyzed. One key outcome is the achievement of uniform and cohesive films at the wafer scale. Structural properties of films are thoroughly detailed, and weight and volume fractions of M/C are considered. Then, a comprehensive overview of DC magnetic and electrical properties is reported. A discussion follows on the magnetic softness of the nanocomposites vs. that of a single particle (theoretical) and the raw powder (experimental). Finally, unprecedented achievement of high magnetization (∼0.6 T) and ultra-high resistivity (∼10{sup 10 }μΩ cm) is shown. High magnetization comes from the preservation of the existing protective shell C, with no significant degradation on the particle net-moment, and high electrical insulation is ensured by adequate grafting of the secondary shell P{sub 1}. To conclude, the metal/polymer nanocomposites are situated in the landscape of soft ferromagnetic materials for RF applications (i.e., inductors and antennas), by means of two phase-diagrams, where they play a crucial role.

  10. Magnetic exitations in the itinerant ferromagnet UFe2

    DEFF Research Database (Denmark)

    Paolasini, L.; Lander, G.H.; Shapiro, S.M.

    1996-01-01

    UFe2 (Laves phase, fee crystal structure) is a ferromagnet with T-C=165 K, Previous neutron elastic measurements have established that the Fe moment is 0.6 mu(B) and that the moment on the U atom is almost zero because of the cancellation of the spin and orbital moments, which are both about 0.23...... electrons. We find also that D is strongly temperature dependent, presumably due to two-magnon interactions. Thus, this effect, together with the low moment on the Fe atoms, results in the comparatively low, as compared to the RFe(2) compounds, T-C of 165 K in UFe2....

  11. Ferromagnetic properties of manganese doped iron silicide

    Science.gov (United States)

    Ruiz-Reyes, Angel; Fonseca, Luis F.; Sabirianov, Renat

    We report the synthesis of high quality Iron silicide (FeSi) nanowires via Chemical Vapor Deposition (CVD). The materials exhibits excellent magnetic response at room temperature, especially when doped with manganese showing values of 2.0 X 10-04 emu for the FexMnySi nanowires. SEM and TEM characterization indicates that the synthesized nanowires have a diameter of approximately 80nm. MFM measurements present a clear description of the magnetic domains when the nanowires are doped with manganese. Electron Diffraction and XRD measurements confirms that the nanowires are single crystal forming a simple cubic structure with space group P213. First-principle calculations were performed on (111) FeSi surface using the Vienna ab initio simulation package (VASP). The exchange correlations were treated under the Ceperley-Alder (CA) local density approximation (LDA). The Brillouin Zone was sampled with 8x8x1 k-point grid. A total magnetic moment of about 10 μB was obtained for three different surface configuration in which the Iron atom nearest to the surface present the higher magnetization. To study the effect of Mn doping, Fe atom was replaced for a Mn. Stronger magnetization is presented when the Mn atom is close to the surface. The exchange coupling constant have been evaluated calculating the energy difference between the ferromagnetic and anti-ferromagnetic configurations.

  12. Magnetic excitations in transition-metal ferromagnets

    International Nuclear Information System (INIS)

    Uemura, Y.J.

    1984-01-01

    A review is given on current neutron scattering experiments at Brookhaven National Laboratory on transition-metal ferromagnets Ni, Fe, Pd 2 MnSn and MnSi. The scattering intensity in constant-energy scans, observed above T/sub c/ in all of these materials, exhibited a clear peak at finite momentum transfers. Using a simple scattering function with double-Lorentzian shape, we demonstrate that this peak is a manifestation of simple diffusive spin fluctuations. Experimental results of several parameters are compared in the context of localized-moment and itinerant-electron pictures. The ratio of spin wave stiffness constant D and transition temperature kT/sub c/ is shown to be a good yardstick for the degree of itinerancy of d-electrons

  13. Ferromagnet / superconductor oxide superlattices

    Science.gov (United States)

    Santamaria, Jacobo

    2006-03-01

    The growth of heterostructures combining oxide materials is a new strategy to design novel artificial multifunctional materials with interesting behaviors ruled by the interface. With the (re)discovery of colossal magnetoresistance (CMR) materials, there has been renewed interest in heterostructures involving oxide superconductors and CMR ferromagnets where ferromagnetism (F) and superconductivity (S) compete within nanometric distances from the interface. In F/S/F structures involving oxides, interfaces are especially complex and various factors like interface disorder and roughness, epitaxial strain, polarity mismatch etc., are responsible for depressed magnetic and superconducting properties at the interface over nanometer length scales. In this talk I will focus in F/S/F structures made of YBa2Cu3O7 (YBCO) and La0.7Ca0.3MnO3 (LCMO). The high degree of spin polarization of the LCMO conduction band, together with the d-wave superconductivity of the YBCO make this F/S system an adequate candidate for the search of novel spin dependent effects in transport. We show that superconductivity at the interface is depressed by various factors like charge transfer, spin injection or ferromagnetic superconducting proximity effect. I will present experiments to examine the characteristic distances of the various mechanisms of superconductivity depression. In particular, I will discuss that the critical temperature of the superconductor depends on the relative orientation of the magnetization of the F layers, giving rise to a new giant magnetoresistance effect which might be of interest for spintronic applications. Work done in collaboration with V. Peña^1, Z. Sefrioui^1, J. Garcia-Barriocanal^1, C. Visani^1, D. Arias^1, C. Leon^1 , N. Nemes^2, M. Garcia Hernandez^2, S. G. E. te Velthuis^3, A. Hoffmann^3, M. Varela^4, S. J. Pennycook^4. Work supported by MCYT MAT 2005-06024, CAM GR- MAT-0771/2004, UCM PR3/04-12399 Work at Argonne supported by the Department of Energy, Basic

  14. Ferromagnetic shape memory materials

    Science.gov (United States)

    Tickle, Robert Jay

    Ferromagnetic shape memory materials are a new class of active materials which combine the properties of ferromagnetism with those of a diffusionless, reversible martensitic transformation. These materials have been the subject of recent study due to the unusually large magnetostriction exhibited in the martensitic phase. In this thesis we report the results of experiments which characterize the magnetic and magnetomechanical properties of both austenitic and martensitic phases of ferromagnetic shape memory material Ni2MnGa. In the high temperature cubic phase, anisotropy and magnetostriction constants are determined for a range of temperatures from 50°C down to the transformation temperature, with room temperature values of K1 = 2.7 +/- 104 ergs/cm3 and lambda100 = -145 muepsilon. In the low temperature tetragonal phase, the phenomenon of field-induced variant rearrangement is shown to produce anomalous results when traditional techniques for determining anisotropy and magnetostriction properties are employed. The requirement of single variant specimen microstructure is explained, and experiments performed on such a specimen confirm a uniaxial anisotropy within each martensitic variant with anisotropy constant Ku = 2.45 x 106 ergs/cm3 and a magnetostriction constant of lambdasv = -288 +/- 73 muepsilon. A series of magnetomechanical experiments investigate the effects of microstructure bias, repeated field cycling, varying field ramp rate, applied load, and specimen geometry on the variant rearrangement phenomenon in the martensitic phase. In general, the field-induced strain is found to be a function of the variant microstructure. Experiments in which the initial microstructure is biased towards a single variant state with an applied load generate one-time strains of 4.3%, while those performed with a constant bias stress of 5 MPa generate reversible strains of 0.5% over a period of 50 cycles. An increase in the applied field ramp rate is shown to reduce the

  15. Petri Nets

    Indian Academy of Sciences (India)

    GENERAL I ARTICLE ... In Part 1 of this two-part article, we have seen im- ..... mable logic controller and VLSI arrays, office automation systems, workflow management systems, ... complex discrete event and real-time systems; and Petri nets.

  16. Absence of field anisotropy in the intrinsic ferromagnetic signals of highly oriented pyrolytic graphite

    International Nuclear Information System (INIS)

    Ballestar, A.; Setzer, A.; Esquinazi, P.; Garcia, N.

    2011-01-01

    We have measured the magnetization of bulk samples of highly oriented pyrolytic graphite (HOPG) at magnetic fields applied parallel and perpendicular to the graphene layers. Within experimental error the intrinsic ferromagnetic signals of the samples show similar magnetic moments at saturation for the two magnetic field directions, in contrast to recently published data (J. Cervenka et al., Nat. Phys. 5 (2009) 840). To check that the SQUID device provides correctly the small ferromagnetic signals obtained after subtracting the 100 times larger diamagnetic background, we have prepared a sample with a superconducting Pb-film deposited on one of the HOPG surfaces. We show that the field dependence of the measured magnetic moment and after the background subtraction is highly reliable even in the sub-μ emu range providing the real magnetic properties of the embedded small ferromagnetic and superconducting signals. - Research Highlights: → We have measured the magnetization of bulk samples of highly oriented pyrolytic graphite (HOPG) at magnetic fields applied parallel and perpendicular to the graphene layers.→ Within experimental error the intrinsic ferromagnetic signals of the samples show similar magnetic moments at saturation for the two magnetic field directions.→ The absence of magnetic anisotropy of the intrinsic ferromagnetic order found in HOPG samples contrasts recently published data by Cervenka et al., Nat Phys 5, 840 (2009).

  17. Room-temperature ferromagnetism in hydrogenated ZnO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Xue, Xudong; Liu, Liangliang; Wang, Zhu; Wu, Yichu, E-mail: ycwu@whu.edu.cn [School of Physics and Technology, Hubei Nuclear Solid Physics Key Laboratory, Wuhan University, Wuhan 430072 (China)

    2014-01-21

    The effect of hydrogen doping on the magnetic properties of ZnO nanoparticles was investigated. Hydrogen was incorporated by annealing under 5% H{sub 2} in Ar ambient at 700 °C. Room-temperature ferromagnetism was induced in hydrogenated ZnO nanoparticles, and the observed ferromagnetism could be switched between “on” and “off” states through hydrogen annealing and oxygen annealing process, respectively. It was found that Zn vacancy and OH bonding complex (V{sub Zn} + OH) was crucial to the observed ferromagnetism by using the X-ray photoelectron spectroscopy and positron annihilation spectroscopy analysis. Based on first-principles calculations, V{sub Zn} + OH was favorable to be presented due to the low formation energy. Meanwhile, this configuration could lead to a magnetic moment of 0.57 μ{sub B}. The Raman and photoluminescence measurements excluded the possibility of oxygen vacancy as the origin of the ferromagnetism.

  18. Optical orientation in ferromagnet/semiconductor hybrids

    International Nuclear Information System (INIS)

    Korenev, V L

    2008-01-01

    The physics of optical pumping of semiconductor electrons in ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of a ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of a semiconductor. Spin–spin interactions near the ferromagnet/semiconductor interface play a crucial role in the optical readout and the manipulation of ferromagnetism

  19. Optical orientation in ferromagnet/semiconductor hybrids

    Science.gov (United States)

    Korenev, V. L.

    2008-11-01

    The physics of optical pumping of semiconductor electrons in ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of a ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of a semiconductor. Spin-spin interactions near the ferromagnet/semiconductor interface play a crucial role in the optical readout and the manipulation of ferromagnetism.

  20. Optical Orientation in Ferromagnet/Semiconductor Hybrids

    OpenAIRE

    Korenev, V. L.

    2008-01-01

    The physics of optical pumping of semiconductor electrons in the ferromagnet/semiconductor hybrids is discussed. Optically oriented semiconductor electrons detect the magnetic state of the ferromagnetic film. In turn, the ferromagnetism of the hybrid can be controlled optically with the help of the semiconductor. Spin-spin interactions near the interface ferromagnet/semiconductor play crucial role in the optical readout and the manipulation of ferromagnetism.

  1. Ferromagnetic Objects Magnetovision Detection System.

    Science.gov (United States)

    Nowicki, Michał; Szewczyk, Roman

    2013-12-02

    This paper presents the application of a weak magnetic fields magnetovision scanning system for detection of dangerous ferromagnetic objects. A measurement system was developed and built to study the magnetic field vector distributions. The measurements of the Earth's field distortions caused by various ferromagnetic objects were carried out. The ability for passive detection of hidden or buried dangerous objects and the determination of their location was demonstrated.

  2. Ferromagnetic Objects Magnetovision Detection System

    Directory of Open Access Journals (Sweden)

    Michał Nowicki

    2013-12-01

    Full Text Available This paper presents the application of a weak magnetic fields magnetovision scanning system for detection of dangerous ferromagnetic objects. A measurement system was developed and built to study the magnetic field vector distributions. The measurements of the Earth’s field distortions caused by various ferromagnetic objects were carried out. The ability for passive detection of hidden or buried dangerous objects and the determination of their location was demonstrated.

  3. Non-ferromagnetic overburden casing

    Science.gov (United States)

    Vinegar, Harold J.; Harris, Christopher Kelvin; Mason, Stanley Leroy

    2010-09-14

    Systems, methods, and heaters for treating a subsurface formation are described herein. At least one system for electrically insulating an overburden portion of a heater wellbore is described. The system may include a heater wellbore located in a subsurface formation and an electrically insulating casing located in the overburden portion of the heater wellbore. The casing may include at least one non-ferromagnetic material such that ferromagnetic effects are inhibited in the casing.

  4. RESTful NET

    CERN Document Server

    Flanders, Jon

    2008-01-01

    RESTful .NET is the first book that teaches Windows developers to build RESTful web services using the latest Microsoft tools. Written by Windows Communication Foundation (WFC) expert Jon Flanders, this hands-on tutorial demonstrates how you can use WCF and other components of the .NET 3.5 Framework to build, deploy and use REST-based web services in a variety of application scenarios. RESTful architecture offers a simpler approach to building web services than SOAP, SOA, and the cumbersome WS- stack. And WCF has proven to be a flexible technology for building distributed systems not necessa

  5. Improved netting

    International Nuclear Information System (INIS)

    Bramley, A.; Clabburn, R.J.T.

    1976-01-01

    A method is described for producing netting composed of longitudinal and transverse threads of irradiation cross linked thermoplastic material, the threads being joined together at their crossings by moulded masses of cross linked thermoplastic material. The thread may be formed of polyethylene filaments, subjected to a radiation dose of 15 to 25 MR. The moulding can be conducted at 245 0 to 260 0 C or higher. The product is claimed to be an improved quality of netting, with bonds of increased strength between crossing threads. (U.K.)

  6. Ferromagnetic ordering and halfmetallic state in a shandite: Co3Sn2S2

    Science.gov (United States)

    Schnelle, Walter; Leithe-Jasper, Andreas; Rosner, Helge; Weihrich, Richard

    2013-03-01

    The rapid advance in spintronics challenges an improved understanding of the underlying microscopic properties. Here, we present a joint experimental and theoretical study of Co3Sn2S2 (shandite) and related compounds. From magnetic susceptibility, specific heat and magneto-transport measurements on a shandite single crystal sample we find a phase transition to a ferromagnetic metallic state at 177 K with a saturation moment of 0.92 μB/f.u. Full potential electronic structure calculations within the local spin density approximation result in a halfmetallic ferromagnetic groundstate with a moment of 1 μB/f.u. and a tiny gap in the minority spin channel. The calculated structure optimization and structure variations show that the size of the gap is rather sensitive to the lattice geometry. Possiblities to stabilize the halfmetallic ferromagnetic behavior by various substitutions have been studied theoretically and will be discussed.

  7. Ferromagnetic characteristics of HfFe2

    International Nuclear Information System (INIS)

    Novakovic, N.; Belosevic-Cavor, J.; Cekic, B.; Manasijevic, M.; Milosevic, Z. . E-mail address of correspoding author: novnik@rt270.vin.bg.ac.yu; Novakovic, N.)

    2003-01-01

    The magnetic hyperfine fields at 181 Ta ion-probe sites in the HfFe 2 polycrystalline binary compound were measured using the time-differential perturbed angular correlation (TDPAC) method. Measurements were performed in the absence of polarizing external magnetic field, at room temperature. The existence of two different structures, dominant cubic MgCu 2 -type and hexagonal MgZn 2 -type in our HfFe 2 sample was refined. Both structures are ferromagnetic with Curie temperatures, which differ significantly (588 K for MgCu 2 and 427 K for MgZn 2 ). The corresponding values of hyperfine fields are H hf 13.8±0.1 T for MgCu 2 -type structure and H hf = 8.0±0.2 T for MgZn 2 -type structure. Calculations using LAPW-Wien 97 program package are in progress and preliminary results are in good agreement with experiment. The analysis includes qualitative explanation of the exchange interactions mechanism between magnetic dipole moment of the observed 181 Ta ion-probe and magnetic dipole moments of the nearest neighbours on the corresponding coordination polyhedra. All these results will be published recently. (author)

  8. Magnetic moments of baryons

    International Nuclear Information System (INIS)

    Lipkin, H.J.

    1983-06-01

    The new experimental values of hyperon magnetic moments are compared with sum rules predicted from general quark models. Three difficulties are encountered which are not easily explained by simple models. The isovector contributions of nonstrange quarks to hyperon moments are smaller than the corresponding contribution to nucleon moments, indicating either appreciable configuration mixing present in hyperon wave functions and absent in nucleons or an additional isovector contribution beyond that of valence quarks; e.g. from a pion cloud. The large magnitude of the ω - moment may indicate that the strange quark contribution to the ω moments is considerably larger than the value μ(#betta#) predicted by simple models which have otherwise been very successful. The set of controversial values from different experiments of the μ - moment include a value very close to -(1/2)μ(μ + ) which would indicate that strange quarks do not contribute at all to the μ moments. (author)

  9. Defect-induced ferromagnetism in semiconductors: A controllable approach by particle irradiation

    International Nuclear Information System (INIS)

    Zhou, Shengqiang

    2014-01-01

    Making semiconductors ferromagnetic has been a long dream. One approach is to dope semiconductors with transition metals (TM). TM ions act as local moments and they couple with free carriers to develop collective magnetism. However, there are no fundamental reasons against the possibility of local moment formation from localized sp states. Recently, ferromagnetism was observed in nonmagnetically doped, but defective semiconductors or insulators including ZnO and TiO 2 . This kind of observation challenges the conventional understanding of ferromagnetism. Often the defect-induced ferromagnetism has been observed in samples prepared under non-optimized condition, i.e. by accident or by mistake. Therefore, in this field theory goes much ahead of experimental investigation. To understand the mechanism of the defect-induced ferromagnetism, one needs a better controlled method to create defects in the crystalline materials. As a nonequilibrium and reproducible approach of inducing defects, ion irradiation provides such a possibility. Energetic ions displace atoms from their equilibrium lattice sites, thus creating mainly vacancies, interstitials or antisites. The amount and the distribution of defects can be controlled by the ion fluence and energy. By ion irradiation, we have generated defect-induced ferromagnetism in ZnO, TiO 2 and SiC. In this short review, we also summarize some results by other groups using energetic ions to introduce defects, and thereby magnetism in various materials. Ion irradiation combined with proper characterizations of defects could allow us to clarify the local magnetic moments and the coupling mechanism in defective semiconductors. Otherwise we may have to build a new paradigm to understand the defect-induced ferromagnetism

  10. Room temperature ferromagnetism in liquid-phase pulsed laser ablation synthesized nanoparticles of nonmagnetic oxides

    International Nuclear Information System (INIS)

    Singh, S. C.; Gopal, R.; Kotnala, R. K.

    2015-01-01

    Intrinsic Room Temperature Ferromagnetism (RTF) has been observed in undoped/uncapped zinc oxide and titanium dioxide spherical nanoparticles (NPs) obtained by a purely green approach of liquid phase pulsed laser ablation of corresponding metal targets in pure water. Saturation magnetization values observed for zinc oxide (average size, 9 ± 1.2 nm) and titanium dioxide (average size, 4.4 ± 0.3 nm) NPs are 62.37 and 42.17 memu/g, respectively, which are several orders of magnitude larger than those of previous reports. In contrast to the previous works, no postprocessing treatments or surface modification is required to induce ferromagnetism in the case of present communication. The most important result, related to the field of intrinsic ferromagnetism in nonmagnetic materials, is the observation of size dependent ferromagnetism. Degree of ferromagnetism in titanium dioxide increases with the increase in particle size, while it is reverse for zinc oxide. Surface and volume defects play significant roles for the origin of RTF in zinc oxide and titanium dioxide NPs, respectively. Single ionized oxygen and neutral zinc vacancies in zinc oxide and oxygen and neutral/ionized titanium vacancies in titanium dioxide are considered as predominant defect centres responsible for observed ferromagnetism. It is expected that origin of ferromagnetism is a consequence of exchange interactions between localized electron spin moments resulting from point defects

  11. Petri Nets

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 4; Issue 9. Petri Nets - Applications. Y Narahari. General Article Volume 4 Issue 9 September 1999 pp 44-52 ... Author Affiliations. Y Narahari1. Department of Computer Science and Automation, Indian Institute of Science, Bangalore 560 012, India.

  12. Net Gain

    International Development Research Centre (IDRC) Digital Library (Canada)

    Describing the effect of tax incentives for import, production, and sale of nets and insecticides; and ..... So far, China is the only country where a system for the routine treatment of ...... 1993), and the trials in Ecuador and Peru (Kroeger et al.

  13. Flocking ferromagnetic colloids.

    Science.gov (United States)

    Kaiser, Andreas; Snezhko, Alexey; Aranson, Igor S

    2017-02-01

    Assemblages of microscopic colloidal particles exhibit fascinating collective motion when energized by electric or magnetic fields. The behaviors range from coherent vortical motion to phase separation and dynamic self-assembly. Although colloidal systems are relatively simple, understanding their collective response, especially under out-of-equilibrium conditions, remains elusive. We report on the emergence of flocking and global rotation in the system of rolling ferromagnetic microparticles energized by a vertical alternating magnetic field. By combing experiments and discrete particle simulations, we have identified primary physical mechanisms, leading to the emergence of large-scale collective motion: spontaneous symmetry breaking of the clockwise/counterclockwise particle rotation, collisional alignment of particle velocities, and random particle reorientations due to shape imperfections. We have also shown that hydrodynamic interactions between the particles do not have a qualitative effect on the collective dynamics. Our findings shed light on the onset of spatial and temporal coherence in a large class of active systems, both synthetic (colloids, swarms of robots, and biopolymers) and living (suspensions of bacteria, cell colonies, and bird flocks).

  14. PREFACE: Half Metallic Ferromagnets

    Science.gov (United States)

    Dowben, Peter

    2007-08-01

    Since its introduction by de Groot and colleagues in the early 1980s [1], the concept of half metallic ferromagnetism has attracted great interest. Idealized, half-metals have only one spin channel for conduction: the spin-polarized band structure exhibits metallic behavior for one spin channel, while the other spin band structure exhibits a gap at the Fermi level. Due to the gap for one spin direction, the density of states at the Fermi level has, theoretically, 100 & spin polarization. This gap in the density of states in one spin at the Fermi level, for example ↓ so N↓ (EF) = 0, also causes the resistance of that channel to go to infinity. At zero or low temperatures, the nonquasiparticle density of states (electron correlation effects), magnons and spin disorder reduce the polarization from the idealized 100 & polarization. At higher temperatures magnon-phonon coupling and irreversible compositional changes affect polarization further. Strategies for assessing and reducing the effects of finite temperatures on the polarization are now gaining attention. The controversies surrounding the polarization stability of half metallic ferromagnets are not, however, limited to the consideration of finite temperature effects alone. While many novel half metallic materials have been predicted, materials fabrication can be challenging. Defects, surface and interface segregation, and structural stability can lead to profound decreases in polarization, but can also suppress long period magnons. There is a 'delicate balance of energies required to obtain half metallic behaviour: to avoid spin flip scattering, tiny adjustments in atomic positions might occur so that a gap opens up in the other spin channel' [2]. When considering 'spintronics' devices, a common alibi for the study of half metallic systems, surfaces and interfaces become important. Free enthalpy differences between the surface and the bulk will lead to spin minority surface and interface states, as well as

  15. Room temperature ferromagnetism in a phthalocyanine based carbon material

    International Nuclear Information System (INIS)

    Honda, Z.; Sato, K.; Sakai, M.; Fukuda, T.; Kamata, N.; Hagiwara, M.; Kida, T.

    2014-01-01

    We report on a simple method to fabricate a magnetic carbon material that contains nitrogen-coordinated transition metals and has a large magnetic moment. Highly chlorinated iron phthalocyanine was used as building blocks and potassium as a coupling reagent to uniformly disperse nitrogen-coordinated iron atoms on the phthalocyanine based carbon material. The iron phthalocyanine based carbon material exhibits ferromagnetic properties at room temperature and the ferromagnetic phase transition occurs at T c  = 490 ± 10 K. Transmission electron microscopy observation, X-ray diffraction analysis, and the temperature dependence of magnetization suggest that the phthalocyanine molecules form three-dimensional random networks in the iron phthalocyanine based carbon material

  16. Room temperature ferromagnetism in a phthalocyanine based carbon material

    Energy Technology Data Exchange (ETDEWEB)

    Honda, Z., E-mail: honda@fms.saitama-u.ac.jp; Sato, K.; Sakai, M.; Fukuda, T.; Kamata, N. [Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama 338-8570 (Japan); Hagiwara, M.; Kida, T. [KYOKUGEN (Center for Quantum Science and Technology under Extreme Conditions), Osaka University, 1-3 Machikaneyama, Toyonaka, Osaka 560-8531 (Japan)

    2014-02-07

    We report on a simple method to fabricate a magnetic carbon material that contains nitrogen-coordinated transition metals and has a large magnetic moment. Highly chlorinated iron phthalocyanine was used as building blocks and potassium as a coupling reagent to uniformly disperse nitrogen-coordinated iron atoms on the phthalocyanine based carbon material. The iron phthalocyanine based carbon material exhibits ferromagnetic properties at room temperature and the ferromagnetic phase transition occurs at T{sub c} = 490 ± 10 K. Transmission electron microscopy observation, X-ray diffraction analysis, and the temperature dependence of magnetization suggest that the phthalocyanine molecules form three-dimensional random networks in the iron phthalocyanine based carbon material.

  17. Detection of ferromagnetic target based on mobile magnetic gradient tensor system

    Energy Technology Data Exchange (ETDEWEB)

    Gang, Y.I.N., E-mail: gang.gang88@163.com; Yingtang, Zhang; Zhining, Li; Hongbo, Fan; Guoquan, Ren

    2016-03-15

    Attitude change of mobile magnetic gradient tensor system critically affects the precision of gradient measurements, thereby increasing ambiguity in target detection. This paper presents a rotational invariant-based method for locating and identifying ferromagnetic targets. Firstly, unit magnetic moment vector was derived based on the geometrical invariant, such that the intermediate eigenvector of the magnetic gradient tensor is perpendicular to the magnetic moment vector and the source–sensor displacement vector. Secondly, unit source–sensor displacement vector was derived based on the characteristic that the angle between magnetic moment vector and source–sensor displacement is a rotational invariant. By introducing a displacement vector between two measurement points, the magnetic moment vector and the source–sensor displacement vector were theoretically derived. To resolve the problem of measurement noises existing in the realistic detection applications, linear equations were formulated using invariants corresponding to several distinct measurement points and least square solution of magnetic moment vector and source–sensor displacement vector were obtained. Results of simulation and principal verification experiment showed the correctness of the analytical method, along with the practicability of the least square method. - Highlights: • Ferromagnetic target detection method is proposed based on rotational invariants • Intermediate eigenvector is perpendicular to magnetic moment and displacement vector • Angle between magnetic moment and displacement vector is a rotational invariant • Magnetic moment and displacement vector are derived based on invariants of two points.

  18. Rise and fall of ferromagnetism in O-irradiated Al{sub 2}O{sub 3} single crystals

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qiang [State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei 230026 (China); China Spallation Neutron Source, Institute of High Energy Physics, Chinese Academy of Sciences, Dongguan 523803 (China); Xu, Juping; Liu, Jiandang; Du, Huaijiang; Ye, Bangjiao, E-mail: bjye@ustc.edu.cn [State Key Laboratory of Particle Detection and Electronics, University of Science and Technology of China, Hefei 230026 (China)

    2015-06-21

    In dilute magnetic semiconductors studies, sapphire was usually used as non-magnetic substrate for films. We observed weak ferromagnetic component in Al{sub 2}O{sub 3} single crystal substrate, and excluded the possibility of ferromagnetic contaminations carefully by inductively coupled plasma mass spectrometry and X-ray photoelectron spectroscopy. The ferromagnetism rise and fall during the process of annealing-oxygen irradiation-annealing of the sapphire. The ferromagnetic changes are consistent with Al-vacancy related defects detected by positron annihilation spectroscopy. With first-principle calculations, we confirm that Al-vacancy can introduce magnetic moment for 3 μB in Al{sub 2}O{sub 3} crystal and form stable V{sub Al}-V{sub Al} ferromagnetic coupling at room temperature.

  19. Net Locality

    DEFF Research Database (Denmark)

    de Souza e Silva, Adriana Araujo; Gordon, Eric

    Provides an introduction to the new theory of Net Locality and the profound effect on individuals and societies when everything is located or locatable. Describes net locality as an emerging form of location awareness central to all aspects of digital media, from mobile phones, to Google Maps......, to location-based social networks and games, such as Foursquare and facebook. Warns of the threats these technologies, such as data surveillance, present to our sense of privacy, while also outlining the opportunities for pro-social developments. Provides a theory of the web in the context of the history...... of emerging technologies, from GeoCities to GPS, Wi-Fi, Wiki Me, and Google Android....

  20. Lepton dipole moments

    CERN Document Server

    Marciano, William J

    2010-01-01

    This book provides a self-contained description of the measurements of the magnetic dipole moments of the electron and muon, along with a discussion of the measurements of the fine structure constant, and the theory associated with magnetic and electric dipole moments. Also included are the searches for a permanent electric dipole moment of the electron, muon, neutron and atomic nuclei. The related topic of the transition moment for lepton flavor violating processes, such as neutrinoless muon or tauon decays, and the search for such processes are included as well. The papers, written by many o

  1. Ferromagnetism in the Hubbard model: a modified perturbation theory

    International Nuclear Information System (INIS)

    Gangadhar Reddy, G.; Ramakanth, A.; Nolting, W.

    2005-01-01

    We study the possibility of ferromagnetism in the Hubbard model using the modified perturbation theory. In this approach an Ansatz is made for the self-energy of the electron which contains the second order contribution developed around the Hartree-Fock solution and two parameters. The parameters are fixed by using a moment method. This self energy satisfies several known exact limiting cases. Using this self energy, the Curie temperature T c as a function of band filling n is investigated. It is found that T c falls off abruptly as n approaches half filling. The results are in qualitative agreement with earlier calculations using other approximation schemes. (author)

  2. Ferromagnetic semiconductor-metal transition in europium monoxide

    International Nuclear Information System (INIS)

    Arnold, M.

    2007-10-01

    We present a microscopical model to describe the simultaneous para-to-ferromagnetic and semiconductor-to-metal transition in electron-doped EuO. The physical properties of the model are systematically studied, whereas the main remark is on the interplay between magnetic order and the transport properties. The theory correctly describes detailed experimental features of the conductivity and of the magnetization, obtained for EuO 1-x or Gd-doped Gd x Eu 1-x 0. In particular the doping dependence of the Curie temperature is reproduced The existence of correlation-induced local moments on the impurity sites is essential for this description. (orig.)

  3. Dynamical response of vibrating ferromagnets

    CERN Document Server

    Gaganidze, E; Ziese, M

    2000-01-01

    The resonance frequency of vibrating ferromagnetic reeds in a homogeneous magnetic field can be substantially modified by intrinsic and extrinsic field-related contributions. Searching for the physical reasons of the field-induced resonance frequency change and to study the influence of the spin glass state on it, we have measured the low-temperature magnetoelastic behavior and the dynamical response of vibrating amorphous and polycrystalline ferromagnetic ribbons. We show that the magnetoelastic properties depend strongly on the direction of the applied magnetic field. The influence of the re-entrant spin glass transition on these properties is discussed. We present clear experimental evidence that for applied fields perpendicular to the main area of the samples the behavior of ferromagnetic reeds is rather independent of the material composition and magnetic state, exhibiting a large decrease of the resonance frequency. This effect can be very well explained with a model based on the dynamical response of t...

  4. Effects of the racket polar moment of inertia on dominant upper limb joint moments during tennis serve.

    Directory of Open Access Journals (Sweden)

    Isabelle Rogowski

    Full Text Available This study examined the effect of the polar moment of inertia of a tennis racket on upper limb loading in the serve. Eight amateur competition tennis players performed two sets of 10 serves using two rackets identical in mass, position of center of mass and moments of inertia other than the polar moment of inertia (0.00152 vs 0.00197 kg.m2. An eight-camera motion analysis system collected the 3D trajectories of 16 markers, located on the thorax, upper limbs and racket, from which shoulder, elbow and wrist net joint moments and powers were computed using inverse dynamics. During the cocking phase, increased racket polar moment of inertia was associated with significant increases in the peak shoulder extension and abduction moments, as well the peak elbow extension, valgus and supination moments. During the forward swing phase, peak wrist extension and radial deviation moments significantly increased with polar moment of inertia. During the follow-through phase, the peak shoulder adduction, elbow pronation and wrist external rotation moments displayed a significant inverse relationship with polar moment of inertia. During the forward swing, the magnitudes of negative joint power at the elbow and wrist were significantly larger when players served using the racket with a higher polar moment of inertia. Although a larger polar of inertia allows players to better tolerate off-center impacts, it also appears to place additional loads on the upper extremity when serving and may therefore increase injury risk in tennis players.

  5. Effects of the racket polar moment of inertia on dominant upper limb joint moments during tennis serve.

    Science.gov (United States)

    Rogowski, Isabelle; Creveaux, Thomas; Chèze, Laurence; Macé, Pierre; Dumas, Raphaël

    2014-01-01

    This study examined the effect of the polar moment of inertia of a tennis racket on upper limb loading in the serve. Eight amateur competition tennis players performed two sets of 10 serves using two rackets identical in mass, position of center of mass and moments of inertia other than the polar moment of inertia (0.00152 vs 0.00197 kg.m2). An eight-camera motion analysis system collected the 3D trajectories of 16 markers, located on the thorax, upper limbs and racket, from which shoulder, elbow and wrist net joint moments and powers were computed using inverse dynamics. During the cocking phase, increased racket polar moment of inertia was associated with significant increases in the peak shoulder extension and abduction moments, as well the peak elbow extension, valgus and supination moments. During the forward swing phase, peak wrist extension and radial deviation moments significantly increased with polar moment of inertia. During the follow-through phase, the peak shoulder adduction, elbow pronation and wrist external rotation moments displayed a significant inverse relationship with polar moment of inertia. During the forward swing, the magnitudes of negative joint power at the elbow and wrist were significantly larger when players served using the racket with a higher polar moment of inertia. Although a larger polar of inertia allows players to better tolerate off-center impacts, it also appears to place additional loads on the upper extremity when serving and may therefore increase injury risk in tennis players.

  6. Electric dipole moments reconsidered

    International Nuclear Information System (INIS)

    Rupertsberger, H.

    1989-01-01

    The electric dipole moments of elementary particles, atoms, molecules and their connection to the electric susceptibility are discussed for stationary states. Assuming rotational invariance it is emphasized that for such states only in the case of a parity and time reversal violating interaction the considered particles can obtain a nonvanishing expectation value for the electric dipole moment. 1 fig., 13 refs. (Author)

  7. Multi-moment maps

    DEFF Research Database (Denmark)

    Swann, Andrew Francis; Madsen, Thomas Bruun

    2012-01-01

    We introduce a notion of moment map adapted to actions of Lie groups that preserve a closed three-form. We show existence of our multi-moment maps in many circumstances, including mild topological assumptions on the underlying manifold. Such maps are also shown to exist for all groups whose second...

  8. Nuclear Anapole Moments

    Energy Technology Data Exchange (ETDEWEB)

    Michael Ramsey-Musolf; Wick Haxton; Ching-Pang Liu

    2002-03-29

    Nuclear anapole moments are parity-odd, time-reversal-even E1 moments of the electromagnetic current operator. Although the existence of this moment was recognized theoretically soon after the discovery of parity nonconservation (PNC), its experimental isolation was achieved only recently, when a new level of precision was reached in a measurement of the hyperfine dependence of atomic PNC in 133Cs. An important anapole moment bound in 205Tl also exists. In this paper, we present the details of the first calculation of these anapole moments in the framework commonly used in other studies of hadronic PNC, a meson exchange potential that includes long-range pion exchange and enough degrees of freedom to describe the five independent S-P amplitudes induced by short-range interactions. The resulting contributions of pi-, rho-, and omega-exchange to the single-nucleon anapole moment, to parity admixtures in the nuclear ground state, and to PNC exchange currents are evaluated, using configuration-mixed shell-model wave functions. The experimental anapole moment constraints on the PNC meson-nucleon coupling constants are derived and compared with those from other tests of the hadronic weak interaction. While the bounds obtained from the anapole moment results are consistent with the broad ''reasonable ranges'' defined by theory, they are not in good agreement with the constraints from the other experiments. We explore possible explanations for the discrepancy and comment on the potential importance of new experiments.

  9. Nuclear Anapole Moments

    International Nuclear Information System (INIS)

    Michael Ramsey-Musolf; Wick Haxton; Ching-Pang Liu

    2002-01-01

    Nuclear anapole moments are parity-odd, time-reversal-even E1 moments of the electromagnetic current operator. Although the existence of this moment was recognized theoretically soon after the discovery of parity nonconservation (PNC), its experimental isolation was achieved only recently, when a new level of precision was reached in a measurement of the hyperfine dependence of atomic PNC in 133Cs. An important anapole moment bound in 205Tl also exists. In this paper, we present the details of the first calculation of these anapole moments in the framework commonly used in other studies of hadronic PNC, a meson exchange potential that includes long-range pion exchange and enough degrees of freedom to describe the five independent S-P amplitudes induced by short-range interactions. The resulting contributions of pi-, rho-, and omega-exchange to the single-nucleon anapole moment, to parity admixtures in the nuclear ground state, and to PNC exchange currents are evaluated, using configuration-mixed shell-model wave functions. The experimental anapole moment constraints on the PNC meson-nucleon coupling constants are derived and compared with those from other tests of the hadronic weak interaction. While the bounds obtained from the anapole moment results are consistent with the broad ''reasonable ranges'' defined by theory, they are not in good agreement with the constraints from the other experiments. We explore possible explanations for the discrepancy and comment on the potential importance of new experiments

  10. The moment problem

    CERN Document Server

    Schmüdgen, Konrad

    2017-01-01

    This advanced textbook provides a comprehensive and unified account of the moment problem. It covers the classical one-dimensional theory and its multidimensional generalization, including modern methods and recent developments. In both the one-dimensional and multidimensional cases, the full and truncated moment problems are carefully treated separately. Fundamental concepts, results and methods are developed in detail and accompanied by numerous examples and exercises. Particular attention is given to powerful modern techniques such as real algebraic geometry and Hilbert space operators. A wide range of important aspects are covered, including the Nevanlinna parametrization for indeterminate moment problems, canonical and principal measures for truncated moment problems, the interplay between Positivstellensätze and moment problems on semi-algebraic sets, the fibre theorem, multidimensional determinacy theory, operator-theoretic approaches, and the existence theory and important special topics of multidime...

  11. STM observations of ferromagnetic clusters

    International Nuclear Information System (INIS)

    Wawro, A.; Kasuya, A.

    1998-01-01

    Co, Fe and Ni clusters of nanometer size, deposited on silicon and graphite (highly oriented pyrolytic graphite), were observed by a scanning tunneling microscope. Deposition as well as the scanning tunneling microscope measurements were carried out in an ultrahigh vacuum system at room temperature. Detailed analysis of Co cluster height was done with the scanning tunneling microscope equipped with a ferromagnetic tip in a magnetic field up to 70 Oe. It is found that bigger clusters (few nanometers in height) exhibit a dependence of their apparent height on applied magnetic field. We propose that such behaviour originates from the ferromagnetic ordering of cluster and associate this effect to spin polarized tunneling. (author)

  12. Magnetic excitations in ferromagnetic semiconductors

    International Nuclear Information System (INIS)

    Furdyna, J.K.; Liu, X.; Zhou, Y.Y.

    2009-01-01

    Magnetic excitations in a series of GaMnAs ferromagnetic semiconductor films were studied by ferromagnetic resonance (FMR). Using the FMR approach, multi-mode spin wave resonance spectra have been observed, whose analysis provides information on magnetic anisotropy (including surface anisotropy), distribution of magnetization precession within the GaMnAs film, dynamic surface spin pinning (derived from surface anisotropy), and the value of exchange stiffness constant D. These studies illustrate a combination of magnetism and semiconductor physics that is unique to magnetic semiconductors

  13. Unusual Co moment reduction in the NiCoO/Co exchange bias system

    Energy Technology Data Exchange (ETDEWEB)

    Brueck, S. [Max-Planck-Institut fuer Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart (Germany)]. E-mail: brueck@mf.mpg.de; Goering, E. [Max-Planck-Institut fuer Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart (Germany); Tang, Y.J. [Center for Magnetic Recording Research, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0401 (United States); Schuetz, G. [Max-Planck-Institut fuer Metallforschung, Heisenbergstrasse 3, D-70569 Stuttgart (Germany); Berkowitz, A.E. [Center for Magnetic Recording Research, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0401 (United States); Department of Physics, University of California at San Diego, 9500 Gilman Dr., La Jolla, CA 92093-0401 (United States)

    2007-03-15

    To answer the question on how the explicit mechanism of coupling in the antiferromagnetic alloy NiCoO is established when in close contact to a ferromagnetic Co layer, X-ray magnetic circular dichroism (XMCD) measurements have been performed. Precise XMCD spectra at the L{sub 2,3}-edge of Ni as well as Co have been obtained at room temperature and at 80K by measuring total electron yield X-ray absorption spectra. The Ni XMCD clearly shows the existence of free, rotatable magnetic Ni moments in the antiferromagnet. As for the Co, XMCD at room temperature shows an average magnetic moment comparable to bulk values. Cooling the sample to 80K decreases the average Co moment by 10%. This decrease is explained by a reduction of ferromagnetic cobalt moments related to antiferromagnetic coupling or pinning close to the interface.

  14. Room temperature d (0) ferromagnetism in hole doped Y2O3: widening the choice of host to tailor DMS.

    Science.gov (United States)

    Chakraborty, Brahmananda; Ramaniah, Lavanya M

    2016-08-24

    Transition metal-free-ferromagnetism in diluted magnetic semiconductors (DMS) is of much current interest in view of the search for more efficient DMS materials for spintronics applications. Our DFT results predict for the first time, that impurities from group1A (Li(+), Na(+), K(+)) doped on Y2O3 can induce a magnetic signature with a magnetic moment around 2.0 μ B per defect at hole concentrations around 1.63  ×  10(21) cm(-3), which is one order less than the critical hole density of ZnO with ferromagnetic coupling large enough to promote room temperature ferromagnetism. The induction of room temperature ferromagnetism by hole doping with an impurity atom from group 1A, which injects two holes per defect in the system, implies that the recommendation of three holes per defect given in the literature, which puts a restriction on the choice of host material and the impurity, is not a necessary criterion for hole induced room temperature ferromagnetism. DFT simulations with the generalized gradient approximation (GGA), confirmed by the more sophisticated hybrid functional, Heyd-Scuseria-Ernzerhof (HSE06), predict that the magnetic moment is mostly contributed by O atoms surrounding the impurity atom and the magnetic moment scale up with impurity concentration which is a positive indicator for practical applications. We quantitatively and extensively demonstrate through the analysis of the density of states and ferromagnetic coupling that the Stoner criterion is satisfied by pushing the Fermi level inside the valence band to activate room temperature ferromagnetism. The stability of the structure and the persistence of ferromagnetism at room temperature were demonstrated by ab initio MD simulations and computation of Curie temperature through the mean field approximation. This study widens the choice of host oxides to tailor DMS for spintronics applications.

  15. Higher Moments of Net Proton Multiplicity Distributions at RHIC

    Czech Academy of Sciences Publication Activity Database

    Aggarwal, M. M.; Ahammed, Z.; Alakhverdyants, A. V.; Alekseev, I.; Alford, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G. S.; Balewski, J.; Barnby, L. S.; Baumgart, S.; Beavis, D.R.; Bellwied, R.; Betancourt, M.J.; Betts, R. R.; Bhasin, A.; Bhati, A.K.; Bichsel, H.; Bielčík, Jaroslav; Bielčíková, Jana; Biritz, B.; Bland, L.C.; Bonner, B.E.; Bouchet, J.; Braidot, E.; Brandin, A.V.; Bridgeman, A.; Bruna, E.; Bueltmann, S.; Bunzarov, I.; Burton, T. P.; Cai, X.Z.; Caines, H.; Sanchez, M.C.D.; Catu, O.; Cebra, D.; Cendejas, R.; Cervantes, M.C.; Chajecki, Z.; Chaloupka, Petr; Chattopadhyay, S.; Chen, H.F.; Chen, J.H.; Chen, J.Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, K.E.; Christie, W.; Chung, P.; Clarke, R.F.; Codrington, M.J.M.; Corliss, R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Leyva, A.D.; De Silva, L.C.; Debbe, R.R.; Dedovich, T. G.; Derevschikov, A.A.; de Souza, R.D.; Didenko, L.; Djawotho, P.; Dogra, S.M.; Dong, X.; Drachenberg, J.L.; Draper, J. E.; Dunlop, J.C.; Mazumdar, M.R.D.; Efimov, L.G.; Elhalhuli, E.; Elnimr, M.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Eun, L.; Evdokimov, O.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Fersch, R.G.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Gagliardi, C. A.; Gangaharan, D.R.; Ganti, M. S.; Garcia-Solis, E.J.; Geromitsos, A.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y.N.; Gordon, A.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Gupta, A.; Gupta, N.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.X.; Harris, J.W.; Hays-Wehle, J.P.; Heinz, M.; Heppelmann, S.; Hirsch, A.; Hjort, E.; Hoffmann, A.M.; Hoffmann, G.W.; Hofman, D.J.; Horner, M.J.; Huang, B.; Huang, H.Z.; Humanic, T.J.; Huo, L.; Igo, G.; Jacobs, P.; Jacobs, W.W.; Jena, C.; Jin, F.; Jones, C.L.; Jones, P.G.; Joseph, J.; Judd, E.G.; Kabana, S.; Kajimoto, K.; Kang, K.; Kapitán, Jan; Kauder, K.; Keane, D.; Kechechyan, A.; Kettler, D.; Kikola, D.P.; Kiryluk, J.; Kisiel, A.; Klein, S.R.; Knospe, A.G.; Kocoloski, A.; Koetke, D.D.; Kollegger, T.; Konzer, J.; Koralt, I.; Koroleva, L.; Korsch, W.; Kotchenda, L.; Kushpil, Vasilij; Kravtsov, P.; Krueger, K.; Krus, M.; Kumar, L.; Kurnadi, P.; Lamont, M.A.C.; Landgraf, J.M.; LaPointe, S. (ed.); Lauret, J.; Lebedev, A.; Lednický, Richard; Lee, Ch.; Lee, J.H.; Leight, W.; LeVine, M.J.; Li, C.; Li, L.; Li, N.; Li, W.; Li, X.; Li, Y.; Li, Z.M.; Lin, G.; Lindenbaum, S.J.; Lisa, M.A.; Liu, F.; Liu, H.; Liu, J.; Ljubicic, T.; Llope, W.J.; Longacre, R.S.; Love, W.A.; Lu, Y.; Luo, X.; Ma, G.L.; Ma, Y.G.; Mahapatra, D. P.; Majka, R.; Mall, O.I.; Mangotra, L.K.; Manweiler, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H.S.; Matulenko, Yu.A.; McDonald, D.; McShane, T.S.; Meschanin, A.; Milner, R.; Minaev, N.G.; Mioduszewski, S.; Mischke, A.; Mitrovski, M.K.; Mohanty, B.; Mondal, M.M.; Morozov, B.; Morozov, D.A.; Munhoz, M. G.; Nandi, B.K.; Nattrass, C.; Nayak, T. K.; Nelson, J.M.; Netrakanti, P.K.; Ng, M.J.; Nogach, L.V.; Nurushev, S.B.; Odyniec, G.; Ogawa, A.; Okorokov, V.; Oldag, E.W.; Olson, D.; Pachr, M.; Page, B.S.; Pal, S.K.; Pandit, Y.; Panebratsev, Yu.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S.C.; Pile, P.; Planinic, M.; Ploskon, M.A.; Pluta, J.; Plyku, D.; Poljak, N.; Poskanzer, A.M.; Potukuchi, B.V.K.S.; Powell, C.B.; Prindle, D.; Pruneau, C.; Pruthi, N.K.; Pujahari, P.R.; Putschke, J.; Raniwala, R.; Raniwala, S.; Ray, R.L.; Redwine, R.; Reed, R.; Ritter, H.G.; Roberts, J.B.; Rogachevskiy, O.V.; Romero, J.L.; Rose, A.; Roy, C.; Ruan, L.; Sahoo, R.; Sakai, S.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sangaline, E.; Schambach, J.; Scharenberg, R.P.; Schmitz, N.; Schuster, T.R.; Seele, J.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, S.S.; Sichtermann, E.P.; Simon, F.; Singaraju, R.N.; Skoby, M.J.; Smirnov, N.; Sorensen, P.; Sowinski, J.; Spinka, H.M.; Srivastava, B.; Stanislaus, T.D.S.; Staszak, D.; Stevens, J.R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M.C.; Subba, N.L.; Šumbera, Michal; Sun, X.M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D.N.; Symons, T.J.M.; de Toledo, A. S.; Takahashi, J.; Tang, A.H.; Tang, Z.; Tarini, L.H.; Tarnowsky, T.; Thein, D.; Thomas, J.H.; Tian, J.; Timmins, A.R.; Timoshenko, S.; Tlustý, David; Tokarev, M. V.; Trainor, T.A.; Tram, V.N.; Trentalange, S.; Tribble, R. E.; Tsai, O.D.; Ulery, J.; Ullrich, T.; Underwood, D.G.; Van Buren, G.; van Leeuwen, M.; van Nieuwenhuizen, G.; Vanfossen, J.A.; Varma, R.; Vasconcelos, G.M.S.; Vasiliev, A. N.; Videbaek, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S.A.; Wada, M.; Walker, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J.S.; Wang, Q.; Wang, X.L.; Wang, Y.; Webb, G.; Westfall, G.D.; Whitten, C.; Wieman, H.; Wissink, S.W.; Witt, R.; Wu, Y.F.; Xie, W.; Xu, N.; Xu, Q.H.; Xu, W.; Xu, Y.; Xu, Z.; Xue, L.; Yang, Y.; Yepes, P.; Yip, K.; Yoo, I.K.; Yue, Q.; Zawisza, M.; Zbroszczyk, H.; Zhan, W.; Zhang, J.B.; Zhang, S.; Zhang, W.M.; Zhang, X.P.; Zhang, Y.; Zhang, Z.P.; Zhao, J.; Zhong, C.; Zhou, J.; Zhou, W.; Zhu, X.; Zhu, Y.H.; Zoulkarneev, R.; Zoulkarneeva, Y.

    2010-01-01

    Roč. 105, č. 2 (2010), 022302/1-022302/6 ISSN 0031-9007 Institutional research plan: CEZ:AV0Z10480505; CEZ:AV0Z10100502 Keywords : QCD PHASE-DIAGRAM * CRITICAL-POINT * TRANSITION Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 7.621, year: 2010

  16. Explanation of ferromagnetism origin in C-doped ZnO by first principle calculations

    International Nuclear Information System (INIS)

    El Amiri, A.; Lassri, H.; Hlil, E.K.; Abid, M.

    2015-01-01

    By ab-initio calculations, we systematically study possible source of ferromagnetism C-doped ZnO compound. The electronic structure and magnetic properties of C-doped ZnO with / without ZnO host and C defects were investigated using the Korringa–Kohn–Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that Zn vacancy and presence of C defects (substitutional, interstitial or combination of both) induce the ferromagnetism in C-doped ZnO. From density of state (DOS) analysis, we show that p–p interaction between C atoms and/or C and O atoms is the mechanism of ferromagnetic coupling in C-doped ZnO. - Highlights: • We study the effect of ZnO host and C defects on ferromagnetism in C-doped ZnO. • Details of KKR method calculations performed to investigate both magnetic and electronic structures. • Magnetic moments, total and partial DOS for C-doped ZnO are well calculated and discussed. • Based on DOS calculations we interpret a origin of ferromagnetism in C-doped ZnO. • Mechanism of ferromagnetic coupling is well proposed

  17. Explanation of ferromagnetism origin in C-doped ZnO by first principle calculations

    Energy Technology Data Exchange (ETDEWEB)

    El Amiri, A., E-mail: aelamiri@casablanca.ma [Laboratoire de Physique Fondamentale et Appliquée (LPFA), Faculté des Sciences Ain Chock, Université Hassan II, B.P. 5366 Mâarif, Casablanca, Maroc (Morocco); Lassri, H. [Laboratoire de Physique des Matériaux, Micro-électronique, Automatique et Thermique (LPMMAT). Faculté des Sciences Ain Chock, Université Hassan II, B.P. 5366 Mâarif, Casablanca, Maroc (Morocco); Hlil, E.K. [Institut Néel, CNRS et Université Joseph Fourier, BP 166, 38042 Grenoble (France); Abid, M. [Laboratoire de Physique Fondamentale et Appliquée (LPFA), Faculté des Sciences Ain Chock, Université Hassan II, B.P. 5366 Mâarif, Casablanca, Maroc (Morocco)

    2015-01-15

    By ab-initio calculations, we systematically study possible source of ferromagnetism C-doped ZnO compound. The electronic structure and magnetic properties of C-doped ZnO with / without ZnO host and C defects were investigated using the Korringa–Kohn–Rostoker (KKR) method combined with coherent potential approximation (CPA). We show that Zn vacancy and presence of C defects (substitutional, interstitial or combination of both) induce the ferromagnetism in C-doped ZnO. From density of state (DOS) analysis, we show that p–p interaction between C atoms and/or C and O atoms is the mechanism of ferromagnetic coupling in C-doped ZnO. - Highlights: • We study the effect of ZnO host and C defects on ferromagnetism in C-doped ZnO. • Details of KKR method calculations performed to investigate both magnetic and electronic structures. • Magnetic moments, total and partial DOS for C-doped ZnO are well calculated and discussed. • Based on DOS calculations we interpret a origin of ferromagnetism in C-doped ZnO. • Mechanism of ferromagnetic coupling is well proposed.

  18. Defect types and room-temperature ferromagnetism in undoped rutile TiO2 single crystals

    Science.gov (United States)

    Li, Dong-Xiang; Qin, Xiu-Bo; Zheng, Li-Rong; Li, Yu-Xiao; Cao, Xing-Zhong; Li, Zhuo-Xin; Yang, Jing; Wang, Bao-Yi

    2013-03-01

    Room-temperature ferromagnetism has been experimentally observed in annealed rutile TiO2 single crystals when a magnetic field is applied parallel to the sample plane. By combining X-ray absorption near the edge structure spectrum and positron annihilation lifetime spectroscopy, Ti3+—VO defect complexes (or clusters) have been identified in annealed crystals at a high vacuum. We elucidate that the unpaired 3d electrons in Ti3+ ions provide the observed room-temperature ferromagnetism. In addition, excess oxygen ions in the TiO2 lattice could induce a number of Ti vacancies which obviously increase magnetic moments.

  19. Ferromagnetic Instability in AFe4Sb12 (A = Ca, Sr, and Ba)

    OpenAIRE

    Matsuoka, E.; Hayashi, K.; Ikeda, A.; Tanaka, K.; Takabatake, T.; Higemoto, W.; Matsumura, M.

    2004-01-01

    Magnetic, transport and thermal properties of AFe4Sb12 (A = Ca, Sr, Ba) are reported. All three compounds show a maximum in both the magnetic susceptibility and thermopower at 50 K, and a large electronic specific heat coefficient of 100 mJ/mol K2. These properties are the characteristics of a nearly ferromagnetic metal. Furthermore, a remanent moment of the order of 10-3muB/Fe was observed below 54, 48, and 40 K for A = Ca, Sr, and Ba, respectively. The volume fraction of the ferromagnetic c...

  20. Defect types and room-temperature ferromagnetism in undoped rutile TiO2 single crystals

    International Nuclear Information System (INIS)

    Li Dong-Xiang; Cao Xing-Zhong; Li Zhuo-Xin; Yang Jing; Wang Bao-Yi; Qin Xiu-Bo; Zheng Li-Rong; Li Yu-Xiao

    2013-01-01

    Room-temperature ferromagnetism has been experimentally observed in annealed rutile TiO 2 single crystals when a magnetic field is applied parallel to the sample plane. By combining X-ray absorption near the edge structure spectrum and positron annihilation lifetime spectroscopy, Ti 3+ —V O defect complexes (or clusters) have been identified in annealed crystals at a high vacuum. We elucidate that the unpaired 3d electrons in Ti 3+ ions provide the observed room-temperature ferromagnetism. In addition, excess oxygen ions in the TiO 2 lattice could induce a number of Ti vacancies which obviously increase magnetic moments

  1. Calculation of ferromagnetic resonance spectra for chains of magnetic particles

    Science.gov (United States)

    Newell, A. J.

    2010-12-01

    Magnetotactic bacteria are a taxonomically diverse group of bacteria that have chains of ferromagnetic crystals inside. These bacteria mostly live in the oxic-anoxic interface (OAI) of aquatic environments. The magnetic chains orient the bacteria parallel to the Earth's magnetic field and help them to maintain their position near the OAI. These chains show the fingerprint of natural selection acting to optimize the magnetic moment per unit iron. This is achieved in a number of ways: the alignment in chains, a narrow size range, crystallographic perfection and chemical purity. Because of these distinctive characteristics, the particles can still be identified after the bacteria have died. Such magnetofossils are useful both as records of bacterial evolution and environmental markers. They can most reliably be identified by microscopy, but that is very labor-intensive. A number of magnetic measurements have been developed to identify magnetofossils quickly and non-invasively. However, the only test that can specifically identify the chain structure is ferromagnetic resonance (FMR), which measures the response to a magnetic field oscillating at microwave frequencies. Although the experimental side of ferromagnetic resonance is well developed, the theoretical models for interpreting them have been limited. A new method is presented for calculating resonance frequencies as well as complete power spectra for chains of interacting magnetic particles. Spectra are calculated and compared with data for magnetotactic bacteria.

  2. Josephson junctions with ferromagnetic interlayer

    International Nuclear Information System (INIS)

    Wild, Georg Hermann

    2012-01-01

    We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO x /Pd 0.82 Ni 0.18 /Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to π-coupling is observed for a thickness d F =6 nm of the ferromagnetic Pd 0.82 Ni 0.18 interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd 0.82 Ni 0.18 has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

  3. Josephson junctions with ferromagnetic interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Wild, Georg Hermann

    2012-03-04

    We report on the fabrication of superconductor/insulator/ferromagnetic metal/superconductor (Nb/AlO{sub x}/Pd{sub 0.82}Ni{sub 0.18}/Nb) Josephson junctions (SIFS JJs) with high critical current densities, large normal resistance times area products, and high quality factors. For these junctions, a transition from 0- to {pi}-coupling is observed for a thickness d{sub F}=6 nm of the ferromagnetic Pd{sub 0.82}Ni{sub 0.18} interlayer. The magnetic field dependence of the critical current of the junctions demonstrates good spatial homogeneity of the tunneling barrier and ferromagnetic interlayer. Magnetic characterization shows that the Pd{sub 0.82}Ni{sub 0.18} has an out-of-plane anisotropy and large saturation magnetization indicating negligible dead layers at the interfaces. A careful analysis of Fiske modes up to about 400 GHz provides valuable information on the junction quality factor and the relevant damping mechanisms. Whereas losses due to quasiparticle tunneling dominate at low frequencies, at high frequencies the damping is explained by the finite surface resistance of the junction electrodes. High quality factors of up to 30 around 200 GHz have been achieved. They allow to study the junction dynamics, in particular the switching probability from the zero-voltage into the voltage state with and without microwave irradiation. The experiments with microwave irradiation are well explained within semi-classical models and numerical simulations. In contrast, at mK temperature the switching dynamics without applied microwaves clearly shows secondary quantum effects. Here, we could observe for the first time macroscopic quantum tunneling in Josephson junctions with a ferromagnetic interlayer. This observation excludes fluctuations of the critical current as a consequence of an unstable magnetic domain structure of the ferromagnetic interlayer and affirms the suitability of SIFS Josephson junctions for quantum information processing.

  4. Quadrupole moments of hadrons

    International Nuclear Information System (INIS)

    Krivoruchenko, M.I.

    1985-01-01

    In chiral bag model an expression is obtained for the quark wave functions with account of color and pion interaction of quarks. The quadrupole moments of nonstrange hadrons are calculated. Quadrupole moment of nucleon isobar is found to be Q(Δ)=-6.3x10 -28 esub(Δ)(cm)sup(2). Fredictions of the chiral bag model are in strong disagreement with the non-relativistic quark model

  5. Particle electric dipole moments

    CERN Document Server

    Pendlebury, J M

    2000-01-01

    Measurements of particle electric dipole moments (EDMs) continue to put powerful constraints on theories of T-symmetry and CP-symmetry violation, which form currently one of the most prominent fields in particle physics. EDM measurements have been concentrated on neutral systems such as the neutron and atoms and molecules. These measurements allow one to deduce, in turn, the electric dipole moments of the fundamental fermions, that is, the lighter leptons and quarks and also those of some heavy nuclei.

  6. Energy gap of ferromagnet-superconductor bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Halterman, Klaus; Valls, Oriol T

    2003-10-15

    The excitation spectrum of clean ferromagnet-superconductor bilayers is calculated within the framework of the self-consistent Bogoliubov-de Gennes theory. Because of the proximity effect, the superconductor induces a gap in the ferromagnet spectrum, for thin ferromagnetic layers. The effect depends strongly on the exchange field in the ferromagnet. We find that as the thickness of the ferromagnetic layer increases, the gap disappears, and that its destruction arises from those quasiparticle excitations with wave vectors mainly along the interface. We discuss the influence that the interface quality and Fermi energy mismatch between the ferromagnet and superconductor have on the calculated energy gap. We also evaluate the density of states in the ferromagnet, and we find it in all cases consistent with the gap results.

  7. Hyperfine fields at some 4d, 5d and 4f impurities in ferromagnetic GdZn and GdCd

    International Nuclear Information System (INIS)

    Kasamatsu, Y.; Kojima, K.; Hihara, T.

    1995-01-01

    Hyperfine (hf) fields at 4d (Y, Nb, Rh, Pd), 5d (Lu, Ta, Ir) and 4f (La, Nd, Sm, Eu) impurities in ferromagnetic GdZn and GdCd have been measured by NMR at 4.2 K. The local moment contributions to the hf field suggest that the impurity moments at the beginning and end of the d series are parallel and antiparallel to Gd moments, respectively. The hf results for 4f impurities are also discussed. ((orig.))

  8. Competition between superconductivity and magnetism in ferromagnet/superconductor heterostructures

    International Nuclear Information System (INIS)

    Izyumov, Yurii A; Proshin, Yurii N; Khusainov, Mensur G

    2002-01-01

    The mutual influence of superconductivity and magnetism in F/S systems, i.e. systems of alternating ferromagnetic (F) and superconducting (S) layers, is comprehensively reviewed. For systems with ferromagnetic metal (FM) layers, a theory of the proximity effect in the dirty limit is constructed based on the Usadel equations. For an FM/S bilayer and an FM/S superlattice, a boundary-value problem involving finite FM/S boundary transparency and the diffusion and wave modes of quasi-particle motion is formulated; and the critical temperature T c is calculated as a function of FM- and S-layer thicknesses. A detailed analysis of a large amount of experimental data amply confirms the proposed theory. It is shown that the superconducting state of an FM/S system is a superposition of two pairing mechanisms, Bardin - Cooper - Schrieffer's in S layers and Larkin - Ovchinnikov - Fulde - Ferrell's in FM ones. The competition between ferromagnetic and antiferromagnetic spontaneous moment orientations in FM layers is explored for the 0- and π-phase superconductivity in FM/S systems. For FI/S structures, where FI is a ferromagnetic insulator, a model for exchange interactions is proposed, which, along with direct exchange inside FI layers, includes indirect Ruderman - Kittel - Kasuya - Yosida exchange between localized spins via S-layer conduction electrons. Within this framework, possible mutual accommodation scenarios for superconducting and magnetic order parameters are found, the corresponding phase diagrams are plotted, and experimental results are explained. The results of the theory of the Josephson effect for S/F/S junctions are presented and the application of the theory of spin-dependent transport to F/S/F junctions is discussed. Application aspects of the subject are examined. (reviews of topical problems)

  9. Blue shift of the plasma edge of a ferromagnetic semimetal

    International Nuclear Information System (INIS)

    Wachter, P.; Bommeli, F.; Degiorgi, L.; Burlet, P.; Bourdarot, F.

    1998-01-01

    Full text: In general rare earth pnictides are semimetals and antiferromagnets. Only some nitrides are quoted as ferri or ferromagnetic. However, it has been shown when prepared stoichiometrically and in single crystalline form the free carrier concentration is only in the percent per cation range, thus they are typical low carrier systems. Under these conditions the nitrides are all canted antiferromagnets and metamagnets, i.e. they show Abstract only. The full magnetic moment only with an applied magnetic field. However, when prepared as single crystals but with excess of the rare earths they become spontaneously ferromagnets due to the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in addition to the superexchange mechanisms. On such ferromagnetic compositions of TbN and GdN and also in EuB 6 a new magneto-optic effect has been discovered, a spontaneous blue shift of the plasma edge upon magnetic order. The plasma edge is measured with optical reflectivity and it depends on the free carrier concentration. In other words the free carrier concentration increases upon ferromagnetic order. This effect can be understood with the spontaneous exchange splitting of mainly the 5d conduction band, lowering the bottom of the spin up 5d band, thus increasing the indirect overlap with the valence p band of the anions and thus enhancing the carrier concentration. This blue shift of the plasma edge follows a spin correlation function. An external magnetic field applied near TC enhances the blue shift since the magnetization is not yet saturated. For T→0 a magnetic field has no effect since the magnetization is spontaneously saturated

  10. Dirac Magnons in Honeycomb Ferromagnets

    Directory of Open Access Journals (Sweden)

    Sergey S. Pershoguba

    2018-01-01

    Full Text Available The discovery of the Dirac electron dispersion in graphene [A. H. Castro Neto, et al., The Electronic Properties of Graphene, Rev. Mod. Phys. 81, 109 (2009RMPHAT0034-686110.1103/RevModPhys.81.109] led to the question of the Dirac cone stability with respect to interactions. Coulomb interactions between electrons were shown to induce a logarithmic renormalization of the Dirac dispersion. With a rapid expansion of the list of compounds and quasiparticle bands with linear band touching [T. O. Wehling, et al., Dirac Materials, Adv. Phys. 63, 1 (2014ADPHAH0001-873210.1080/00018732.2014.927109], the concept of bosonic Dirac materials has emerged. We consider a specific case of ferromagnets consisting of van der Waals-bonded stacks of honeycomb layers, e.g., chromium trihalides CrX_{3} (X=F, Cl, Br and I, that display two spin wave modes with energy dispersion similar to that for the electrons in graphene. At the single-particle level, these materials resemble their fermionic counterparts. However, how different particle statistics and interactions affect the stability of Dirac cones has yet to be determined. To address the role of interacting Dirac magnons, we expand the theory of ferromagnets beyond the standard Dyson theory [F. J. Dyson, General Theory of Spin-Wave Interactions, Phys. Rev. 102, 1217 (1956PHRVAO0031-899X10.1103/PhysRev.102.1217, F. J. Dyson, Thermodynamic Behavior of an Ideal Ferromagnet, Phys. Rev. 102, 1230 (1956PHRVAO0031-899X10.1103/PhysRev.102.1230] to the case of non-Bravais honeycomb layers. We demonstrate that magnon-magnon interactions lead to a significant momentum-dependent renormalization of the bare band structure in addition to strongly momentum-dependent magnon lifetimes. We show that our theory qualitatively accounts for hitherto unexplained anomalies in nearly half-century-old magnetic neutron-scattering data for CrBr_{3} [W. B. Yelon and R. Silberglitt, Renormalization of Large-Wave-Vector Magnons in

  11. Dirac Magnons in Honeycomb Ferromagnets

    Science.gov (United States)

    Pershoguba, Sergey S.; Banerjee, Saikat; Lashley, J. C.; Park, Jihwey; Ågren, Hans; Aeppli, Gabriel; Balatsky, Alexander V.

    2018-01-01

    The discovery of the Dirac electron dispersion in graphene [A. H. Castro Neto, et al., The Electronic Properties of Graphene, Rev. Mod. Phys. 81, 109 (2009), 10.1103/RevModPhys.81.109] led to the question of the Dirac cone stability with respect to interactions. Coulomb interactions between electrons were shown to induce a logarithmic renormalization of the Dirac dispersion. With a rapid expansion of the list of compounds and quasiparticle bands with linear band touching [T. O. Wehling, et al., Dirac Materials, Adv. Phys. 63, 1 (2014), 10.1080/00018732.2014.927109], the concept of bosonic Dirac materials has emerged. We consider a specific case of ferromagnets consisting of van der Waals-bonded stacks of honeycomb layers, e.g., chromium trihalides CrX3 (X =F , Cl, Br and I), that display two spin wave modes with energy dispersion similar to that for the electrons in graphene. At the single-particle level, these materials resemble their fermionic counterparts. However, how different particle statistics and interactions affect the stability of Dirac cones has yet to be determined. To address the role of interacting Dirac magnons, we expand the theory of ferromagnets beyond the standard Dyson theory [F. J. Dyson, General Theory of Spin-Wave Interactions, Phys. Rev. 102, 1217 (1956), 10.1103/PhysRev.102.1217, F. J. Dyson, Thermodynamic Behavior of an Ideal Ferromagnet, Phys. Rev. 102, 1230 (1956), 10.1103/PhysRev.102.1230] to the case of non-Bravais honeycomb layers. We demonstrate that magnon-magnon interactions lead to a significant momentum-dependent renormalization of the bare band structure in addition to strongly momentum-dependent magnon lifetimes. We show that our theory qualitatively accounts for hitherto unexplained anomalies in nearly half-century-old magnetic neutron-scattering data for CrBr3 [W. B. Yelon and R. Silberglitt, Renormalization of Large-Wave-Vector Magnons in Ferromagnetic CrBr3 Studied by Inelastic Neutron Scattering: Spin-Wave Correlation

  12. Exchange bias in nearly perpendicularly coupled ferromagnetic/ferromagnetic system

    International Nuclear Information System (INIS)

    Bu, K.M.; Kwon, H.Y.; Oh, S.W.; Won, C.

    2012-01-01

    Exchange bias phenomena appear not only in ferromagnetic/antiferromagnetic systems but also in ferromagnetic/ferromagnetic systems in which two layers are nearly perpendicularly coupled. We investigated the origin of the symmetry-breaking mechanism and the relationship between the exchange bias and the system's energy parameters. We compared the results of computational Monte Carlo simulations with those of theoretical model calculation. We found that the exchange bias exhibited nonlinear behaviors, including sign reversal and singularities. These complicated behaviors were caused by two distinct magnetization processes depending on the interlayer coupling strength. The exchange bias reached a maximum at the transition between the two magnetization processes. - Highlights: ► Exchange bias phenomena are found in perpendicularly coupled F/F systems. ► Exchange bias exhibits nonlinear behaviors, including sign reversal and singularities. ► These complicated behaviors were caused by two distinct magnetization processes. ► Exchange bias reached a maximum at the transition between the two magnetization processes. ► We established an equation to maximize the exchange bias in perpendicularly coupled F/F system.

  13. Superconducting magnetoresistance in ferromagnet/superconductor/ferromagnet trilayers.

    Science.gov (United States)

    Stamopoulos, D; Aristomenopoulou, E

    2015-08-26

    Magnetoresistance is a multifaceted effect reflecting the diverse transport mechanisms exhibited by different kinds of plain materials and hybrid nanostructures; among other, giant, colossal, and extraordinary magnetoresistance versions exist, with the notation indicative of the intensity. Here we report on the superconducting magnetoresistance observed in ferromagnet/superconductor/ferromagnet trilayers, namely Co/Nb/Co trilayers, subjected to a parallel external magnetic field equal to the coercive field. By manipulating the transverse stray dipolar fields that originate from the out-of-plane magnetic domains of the outer layers that develop at coercivity, we can suppress the supercurrent of the interlayer. We experimentally demonstrate a scaling of the magnetoresistance magnitude that we reproduce with a closed-form phenomenological formula that incorporates relevant macroscopic parameters and microscopic length scales of the superconducting and ferromagnetic structural units. The generic approach introduced here can be used to design novel cryogenic devices that completely switch the supercurrent 'on' and 'off', thus exhibiting the ultimate magnetoresistance magnitude 100% on a regular basis.

  14. Control of room-temperature defect-mediated ferromagnetism in VO{sub 2} films

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Tsung-Han, E-mail: tyang3@ncsu.edu [NSF Center for Advanced Materials and Smart Structures, Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7907 (United States); Nori, Sudhakar; Mal, Siddhartha; Narayan, Jagdish [NSF Center for Advanced Materials and Smart Structures, Department of Materials Science and Engineering, North Carolina State University, Raleigh, NC 27695-7907 (United States)

    2011-09-15

    We report interesting ferromagnetic properties and their control in a vanadium-based oxide system driven by stoichiometric defects. Vanadium oxide (VO{sub 2}) thin films were grown on c-plane sapphire substrates by a pulsed laser deposition technique under different ambient conditions. The ferromagnetism of the epitaxial VO{sub 2} films can be switched on and off by altering the cooling ambient parameters. In addition, the saturated magnetic moments and coercivity of the VO{sub 2} films were found to be a function of the oxygen partial pressure during the growth process. The room-temperature ferromagnetic properties of VO{sub 2} films were correlated with the nature of the microstructure and the growth parameters. The origin of the induced magnetic properties are qualitatively understood to stem from intrinsic structural and stoichiometric defects.

  15. Magneto-optical Kerr-effect at low temperatures. Investigation of superconductor/ferromagnet heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zahn, Patrick; Bayer, Jonas [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Institute for Innovative Surfaces FINO, Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany); Stahl, Claudia; Ruoss, Stephen; Graefe, Joachim; Schuetz, Gisela [Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart (Germany); Albrecht, Joachim [Institute for Innovative Surfaces FINO, Aalen University, Beethovenstrasse 1, 73430 Aalen (Germany)

    2016-07-01

    With XMCD microscopy it is possible to visualize the critical current density of the superconductor YBCO with high spatial resolution. Therefore, soft magnetic CoFeB is introduced as sensor layer. The magnetic stray fields of the supercurrents lead to a local reorientation of the magnetic moments in the ferromagnet, which are then imaged via X-ray microscopy. These experiments have to be carried out at the scanning X-ray microscope MAXYMUS at the synchrotron Bessy II in Berlin. For that purpose pre-characterization of the sensor is highly desirable: Magnetic interactions between the superconductor and the ferromagnetic sensor layer have been investigated at low temperatures using Kerr-effect measurements. Therefore hysteresis loops are obtained by a sophisticated magnet and field ramping setup within the NanoMOKE3 system. The results are used to optimize the ferromagnetic sensor layer for XMCD microscopy of superconductors.

  16. Anion vacancy-mediated ferromagnetism in atomic-thick Ni3N nanosheets

    Science.gov (United States)

    Xia, Baorui; Wang, Tongtong; Chi, Xiao; Yu, Xiaojiang; Liu, Peitao; Zhang, Jingyan; Xi, Shibo; Du, Yonghua; Gao, Daqiang

    2017-12-01

    Realizing spin and electronic behavior of two-dimensional ultrathin nanosheets is significant to construct next generation nanoelectronics. Here, atomic-thick Ni3N nanosheets with clear room temperature ferromagnetism and high saturation magnetization (1.2 emu/g) are reported. X-ray magnetic circular dichroism and first-principles calculation results give the evidence that the observed intrinsic ferromagnetism in Ni3N nanosheets originates from the surface N-deficiency, where alignments of localized large magnetic moments of Ni in the vicinity of the N defect can be aligned parallel to activate macroscopic ferromagnetism. These ultrathin Ni3N nanosheets show great potential application in next-generation electron devices.

  17. Magnetic excitations in amorphous ferromagnets

    International Nuclear Information System (INIS)

    Continentino, M.A.

    The propagation of magnetic excitations in amorphous ferromagnets is studied from the point of view of the theory of random frequency modulation. It is shown that the spin waves in the hydrodynamic limit are well described by perturbation theory while the roton-like magnetic excitations with wavevector about the peak in the structure factor are not. A criterion of validity of perturbation theory is found which is identical to a narrowing condition in magnetic resonance. (author) [pt

  18. Moment magnitude scale

    Energy Technology Data Exchange (ETDEWEB)

    Hanks, T.C.; Kanamori, H.

    1979-05-10

    The nearly conincident forms of the relations between seismic moment M/sub o/ and the magnitudes M/sub L/, M/sub s/, and M/sub w/ imply a moment magnitude scale M=2/3 log M/sub o/-10.7 which is uniformly valid for 3< or approx. =M/sub L/< or approx. = 7, 5 < or approx. =M/sub s/< or approx. =7 1/2 and M/sub w/> or approx. = 7 1/2.

  19. Magnetic moments of hyperons

    International Nuclear Information System (INIS)

    Overseth, O.E.

    1981-01-01

    The Fermilab Neutral Hyperon Beam Collaboration has measured the magnetic moments of Λ 0 , XI-neutral and XI-minus hyperons. With a recently published result for the Σ + hyperon, we now have precision measurements on the magnetic moments of six baryons. This allows a sensitive test of the quark model. The data are in qualitative agreement with the simple additive static quark model. Quantitatively however the data disagree with theoretical predictions by typically 15%. Several theoretical attempts to understand or remedy this discrepancy will be mentioned

  20. Formation of spin-polarons in the ferromagnetic Kondo lattice model away from half-filling

    International Nuclear Information System (INIS)

    Arredondo, Y; Navarro, O; Vallejo, E; Avignon, M

    2012-01-01

    Even though realistic one-dimensional experiments in the field of half-metallic semiconductors are not at hand yet, we are interested in the underlying fundamental physics. In this regard we study a one-dimensional ferromagnetic Kondo lattice model, a model in which a conduction band is coupled ferromagnetically to a background of localized d moments with coupling constant J H , and investigate the T = 0 phase diagram as a function of the antiferromagnetic interaction J between the localized moments and the band-filling n, since it has been observed that doping of the compounds has led to formation of magnetic domains. We explore the spin-polaron formation by looking at the nearest-neighbour correlation functions in the spin and charge regimes for which we use the density matrix renormalization group method, which is a highly efficient method to investigate quasi-one-dimensional strongly correlated systems. (paper)

  1. Defect induced ferromagnetism in MgO nanoparticles studied by optical and positron annihilation spectroscopy

    Science.gov (United States)

    Kumar, Nitesh; Sanyal, D.; Sundaresan, A.

    2009-08-01

    Positron annihilation spectroscopy has been used to explore the nature of defects and to estimate the defect concentrations in ferromagnetic MgO nanoparticles. Our experimental results show that Mg vacancies or Mg vacancy concentration are present approximately at the concentration of 3.4 × 10 16 cm -3 in the nano-crystalline MgO which is twice the value that obtained for bulk sample. This is in correlation with the decrease of the intensity of blue luminescence and the saturation magnetic moment with increasing particle size. These results clearly demonstrate that the origin of magnetic moment and thus the ferromagnetism in MgO nanoparticles is due to Mg related vacancies at the surface of the particles.

  2. Room temperature ferromagnetism in Fe-doped semiconductor ZrS2 single crystals

    Science.gov (United States)

    Muhammad, Zahir; Lv, Haifeng; Wu, Chuanqiang; Habib, Muhammad; Rehman, Zia ur; Khan, Rashid; Chen, Shuangming; Wu, Xiaojun; Song, Li

    2018-04-01

    Two dimensional (2D) layered magnetic materials have obtained much attention due to their intriguing properties with a potential application in the field of spintronics. Herein, room-temperature ferromagnetism with 0.2 emu g‑1 magnetic moment is realized in Fe-doped ZrS2 single crystals of millimeter size, in comparison with diamagnetic behaviour in ZrS2. The electron paramagnetic resonance spectroscopy reveals that 5.2wt% Fe-doping ZrS2 crystal exhibit high spin value of g-factor about 3.57 at room temperature also confirmed this evidence, due to the unpaired electrons created by doped Fe atoms. First principle static electronic and magnetic calculations further confirm the increased stability of long range ferromagnetic ordering and enhanced magnetic moment in Fe-doped ZrS2, originating from the Fe spin polarized electron near the Fermi level.

  3. Low temperature enhancement of ferromagnetic Kitaev correlations in {\\alpha}-RuCl3

    OpenAIRE

    Koitzsch, Andreas; Mueller, Eric; Knupfer, Martin; Buechner, Bernd; Nowak, Domenic; Isaeva, Anna; Doert, Thomas; Grueninger, Markus; Nishimoto, Satoshi; Brink, Jeroen van den

    2017-01-01

    Kitaev-type interactions between neighbouring magnetic moments emerge in the honeycomb material ${\\alpha}$-RuCl3. It is debated however whether these Kitaev interactions are ferromagnetic or antiferromagnetic. With electron energy loss spectroscopy (EELS) we study the lowest excitation across the Mott-Hubbard gap, which involves a d4 triplet in the final state and therefore is sensitive to nearest-neighbor spin-spin correlations. At low temperature the spectral weight of these triplets is str...

  4. Efficiency of homopolar generators without ferromagnetic circuit

    International Nuclear Information System (INIS)

    Kharitonov, V.V.

    1982-01-01

    E.m.f. and weights of homopolar generators (HG) without a ferromagnetic circuit and of similar generator with a ferromagnetic circuit are compared at equal armature diameters and armature rotative speed. HG without ferromagnetic cuircuit of disk and cylinder types with hot and superconducting excitation winding are considered. Areas of the most reasonable removal of a ferromagnetic circuit in the HG layout are found. The plots of relationships between the e.m.f. and HG weight that permit to estimate the efficiency of ''nonferrite'' HG constructions are presented

  5. Possibilistic Fuzzy Net Present Value Model and Application

    Directory of Open Access Journals (Sweden)

    S. S. Appadoo

    2014-01-01

    Full Text Available The cash flow values and the interest rate in the net present value (NPV model are usually specified by either crisp numbers or random variables. In this paper, we first discuss some of the recent developments in possibility theory and find closed form expressions for fuzzy possibilistic net present value (FNPV. Then, following Carlsson and Fullér (2001, we discuss some of the possibilistic moments related to FNPV model along with an illustrative numerical example. We also give a unified approach to find higher order moments of FNPV by using the moment generating function introduced by Paseka et al. (2011.

  6. Moments of Negotiation

    NARCIS (Netherlands)

    Pieters, Jurgen

    2001-01-01

    'Moments of Negotiation' offers the first book-length and indepth analysis of the New Historicist reading method, which the American Shakespeare-scolar Stephen Greenblatt introduced at the beginning of the 1980s. Ever since, Greenblatt has been hailed as the prime representative of this movement,

  7. Magnetic moments revisited

    International Nuclear Information System (INIS)

    Towner, I.S.; Khanna, F.C.

    1984-01-01

    Consideration of core polarization, isobar currents and meson-exchange processes gives a satisfactory understanding of the ground-state magnetic moments in closed-shell-plus (or minus)-one nuclei, A = 3, 15, 17, 39 and 41. Ever since the earliest days of the nuclear shell model the understanding of magnetic moments of nuclear states of supposedly simple configurations, such as doubly closed LS shells +-1 nucleon, has been a challenge for theorists. The experimental moments, which in most cases are known with extraordinary precision, show a small yet significant departure from the single-particle Schmidt values. The departure, however, is difficult to evaluate precisely since, as will be seen, it results from a sensitive cancellation between several competing corrections each of which can be as large as the observed discrepancy. This, then, is the continuing fascination of magnetic moments. In this contribution, we revisit the subjet principally to identify the role played by isobar currents, which are of much concern at this conference. But in so doing we warn quite strongly of the dangers of considering just isobar currents in isolation; equal consideration must be given to competing processes which in this context are the mundane nuclear structure effects, such as core polarization, and the more popular meson-exchange currents

  8. The Humanist Moment

    Science.gov (United States)

    Higgins, Chris

    2014-01-01

    In "The Humanist Moment," Chris Higgins sets out to recover a tenable, living humanism, rejecting both the version vilified by the anti-humanists and the one sentimentalized by the reactionary nostalgists. Rescuing humanism from such polemics is only the first step, as we find at least nine rival, contemporary definitions of humanism.…

  9. Strong room-temperature ferromagnetism in VSe2 monolayers on van der Waals substrates

    Science.gov (United States)

    Bonilla, Manuel; Kolekar, Sadhu; Ma, Yujing; Diaz, Horacio Coy; Kalappattil, Vijaysankar; Das, Raja; Eggers, Tatiana; Gutierrez, Humberto R.; Phan, Manh-Huong; Batzill, Matthias

    2018-04-01

    Reduced dimensionality and interlayer coupling in van der Waals materials gives rise to fundamentally different electronic1, optical2 and many-body quantum3-5 properties in monolayers compared with the bulk. This layer-dependence permits the discovery of novel material properties in the monolayer regime. Ferromagnetic order in two-dimensional materials is a coveted property that would allow fundamental studies of spin behaviour in low dimensions and enable new spintronics applications6-8. Recent studies have shown that for the bulk-ferromagnetic layered materials CrI3 (ref. 9) and Cr2Ge2Te6 (ref. 10), ferromagnetic order is maintained down to the ultrathin limit at low temperatures. Contrary to these observations, we report the emergence of strong ferromagnetic ordering for monolayer VSe2, a material that is paramagnetic in the bulk11,12. Importantly, the ferromagnetic ordering with a large magnetic moment persists to above room temperature, making VSe2 an attractive material for van der Waals spintronics applications.

  10. Magnetization reversal of ferromagnetic nanoparticles induced by a stream of polarized electrons

    Energy Technology Data Exchange (ETDEWEB)

    Kozhushner, M.A.; Gatin, A.K.; Grishin, M.V.; Shub, B.R. [Semenov Institute of Chemical Physics of RAS, 4, Kosygin Street, Moscow 119991 (Russian Federation); Kim, V.P.; Khomutov, G.B. [Faculty of Physics, Lomonosov Moscow State University, Lenin Gory 1-2, Moscow 119991 (Russian Federation); Ilegbusi, O.J. [University of Central Florida, 4000 Central Florida Boulevard, Orlando, FL 32816-2450 (United States); Trakhtenberg, L.I. [Semenov Institute of Chemical Physics of RAS, 4, Kosygin Street, Moscow 119991 (Russian Federation)

    2016-09-15

    The remagnetization of ferromagnetic Fe{sub 3}O{sub 4} nanoparticles of several thousand cubic nanometers by spin-polarized current is investigated. For this purpose, magnetite nanoparticles are synthesized and deposited on a conductive nonmagnetic substrate. The remagnetization is conducted in high-vacuum scanning tunneling microscope (STM). The STM tip from magnetized iron wire constitutes one electrode while the ferromagnetic nanoparticle on the graphite surface represents the second electrode. The measured threshold value of remagnetization current (I{sub thresh}=9 nA) is the lowest value of current at which remagnetization occurs. The change in nanoparticle magnetization is detected by the effect of giant magnetic resistance, specifically, the dependence of the weak polarized current (Imoment of small ferromagnetic nanoclusters. The peculiarities of size dependence of the observed effects are explained. - Highlights: • Ferromagnetic nanoparticle in STM with ferromagnetic tip. • Change of the direction of nanoparticle magnetization by current I>I{sub cr}=9 nA. • GMR effect used to control change of magnetization.

  11. The Definitive Guide to NetBeans Platform

    CERN Document Server

    Bock, Heiko

    2009-01-01

    The Definitive Guide to NetBeans(t) Platform is a thorough and definitive introduction to the NetBeans Platform, covering all its major APIs in detail, with relevant code examples used throughout. The original German book on which this title is based was well received. The NetBeans Platform Community has put together this English translation, which author Heiko Bock updated to cover the latest NetBeans Platform 6.5 APIs. With an introduction by known NetBeans Platform experts Jaroslav Tulach, Tim Boudreau, and Geertjan Wielenga, this is the most up-to-date book on this topic at the moment. All

  12. Significant room-temperature ferromagnetism in porous ZnO films: The role of oxygen vacancies

    Energy Technology Data Exchange (ETDEWEB)

    Hou, Xue; Liu, Huiyuan [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Sun, Huiyuan, E-mail: huiyuansun@126.com [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China); Liu, Lihu; Jia, Xiaoxuan [College of Physics Science & Information Engineering, Hebei Normal University, Shijiazhuang 050024 (China); Key Laboratory of Advanced Films of Hebei Province, Shijiazhuang 050024 (China)

    2015-10-15

    Graphical abstract: - Highlights: • Porous ZnO films were deposited on porous anodic alumina substrates. • Significant ferromagnetism (FM) has been observed in porous ZnO films (110 emu/cm{sup 3}). • The strong magnetic anisotropy was observed in the porous ZnO films. • The origin of FM is attributed to the oxygen vacancy with a local magnetic moment. - Abstract: Pure porous ZnO films were prepared by direct current reactive magnetron sputtering on porous anodic alumina substrates. Remarkably large room-temperature ferromagnetism was observed in the films. The highest saturation moment along the out-of-plane direction was about 110 emu/cm{sup 3}. Experimental and theoretical results suggested that the oxygen vacancies and the unique porous structure of the films are responsible for the large ferromagnetism. There are two modes of coupling between oxygen vacancies in the porous ZnO films: (i) exchange interactions directly between the oxygen vacancies and (ii) with the mediation of conduction electrons. In addition, it was found that the magnetic moment of ZnO films can be changed by tuning the concentration of oxygen vacancies. These observations may be useful in the development of ZnO-based spintronics devices.

  13. Radioactive Probes on Ferromagnetic Surfaces

    CERN Multimedia

    2002-01-01

    On the (broad) basis of our studies of nonmagnetic radioactive probe atoms on magnetic surfaces and at interfaces, we propose to investigate the magnetic interaction of magnetic probe atoms with their immediate environment, in particular of rare earth (RE) elements positioned on and in ferromagnetic surfaces. The preparation and analysis of the structural properties of such samples will be performed in the UHV chamber HYDRA at the HMI/Berlin. For the investigations of the magnetic properties of RE atoms on surfaces Perturbed Angular Correlation (PAC) measurements and Mössbauer Spectroscopy (MS) in the UHV chamber ASPIC (Apparatus for Surface Physics and Interfaces at CERN) are proposed.

  14. Redefining the political moment

    Directory of Open Access Journals (Sweden)

    James Arvanitakis

    2011-07-01

    Full Text Available On 16 February 2003, more than half a million people gathered in Sydney, Australia, as part of a global anti-war protest aimed at stopping the impending invasion of Iraq by the then US Administration. It is difficult to estimate how many millions marched on the coordinated protest, but it was by far the largest mobilization of a generation. Walking and chanting on the streets of Sydney that day, it seemed that a political moment was upon us. In a culture that rarely embraces large scale activism, millions around Australian demanded to be heard. The message was clear: if you do not hear us, we would be willing to bring down a government. The invasion went ahead, however, with the then Australian government, under the leadership of John Howard, being one of the loudest and staunchest supporters of the Bush Administrations drive to war. Within 18 months, anti-war activists struggled to have a few hundred participants take part in anti-Iraq war rallies, and the Howard Government was comfortably re-elected for another term. The political moment had come and gone, with both social commentators and many members of the public looking for a reason. While the conservative media was often the focus of analysis, this paper argues that in a time of late capitalism, the political moment is hollowed out by ‘Politics’ itself. That is to say, that formal political processes (or ‘Politics’ undermine the political practices that people participate in everyday (or ‘politics’. Drawing on an ongoing research project focusing on democracy and young people, I discuss how the concept of ’politics‘ has been destabilised and subsequently, the political moment has been displaced. This displacement has led to a re-definition of ‘political action’ and, I argue, the emergence of a different type of everyday politics.

  15. Projective moment invariants

    Czech Academy of Sciences Publication Activity Database

    Suk, Tomáš; Flusser, Jan

    2004-01-01

    Roč. 26, č. 10 (2004), s. 1364-1367 ISSN 0162-8828 R&D Projects: GA ČR GA201/03/0675 Institutional research plan: CEZ:AV0Z1075907 Keywords : projective transform * moment invariants * object recognition Subject RIV: JD - Computer Applications, Robotics Impact factor: 4.352, year: 2004 http://library.utia.cas.cz/prace/20040112.pdf

  16. Onset of itinerant ferromagnetism associated with semiconductor ...

    Indian Academy of Sciences (India)

    In this paper, the magnetic and transport properties of the TiNb1−CoSn solid solution compounds with half Heusler cubic MgAgAs-type structure have been studied. This work shows the onset of ferromagnetism associated with a semiconductor to metal transition. The transition occurs directly from ferromagnetic metal to ...

  17. Voltage control of ferromagnetic resonance

    Directory of Open Access Journals (Sweden)

    Ziyao Zhou

    2016-06-01

    Full Text Available Voltage control of magnetism in multiferroics, where the ferromagnetism and ferroelectricity are simultaneously exhibiting, is of great importance to achieve compact, fast and energy efficient voltage controllable magnetic/microwave devices. Particularly, these devices are widely used in radar, aircraft, cell phones and satellites, where volume, response time and energy consumption is critical. Researchers realized electric field tuning of magnetic properties like magnetization, magnetic anisotropy and permeability in varied multiferroic heterostructures such as bulk, thin films and nanostructure by different magnetoelectric (ME coupling mechanism: strain/stress, interfacial charge, spin–electromagnetic (EM coupling and exchange coupling, etc. In this review, we focus on voltage control of ferromagnetic resonance (FMR in multiferroics. ME coupling-induced FMR change is critical in microwave devices, where the electric field tuning of magnetic effective anisotropic field determines the tunability of the performance of microwave devices. Experimentally, FMR measurement technique is also an important method to determine the small effective magnetic field change in small amount of magnetic material precisely due to its high sensitivity and to reveal the deep science of multiferroics, especially, voltage control of magnetism in novel mechanisms like interfacial charge, spin–EM coupling and exchange coupling.

  18. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt

    1987-01-01

    The author describes a Petri net model, called coloured Petri nets (CP-nets), by means of which it is possible to describe large systems without having to cope with unnecessary details. The author introduces CP-nets and provide a first impression of their modeling power and the suitability...

  19. Learning Visual Basic NET

    CERN Document Server

    Liberty, Jesse

    2009-01-01

    Learning Visual Basic .NET is a complete introduction to VB.NET and object-oriented programming. By using hundreds of examples, this book demonstrates how to develop various kinds of applications--including those that work with databases--and web services. Learning Visual Basic .NET will help you build a solid foundation in .NET.

  20. Heavy quark and magnetic moment

    International Nuclear Information System (INIS)

    Mubarak, Ahmad; Jallu, M.S.

    1979-01-01

    The magnetic moments and transition moments of heavy hadrons including the conventional particles are obtained under the SU(5) truth symmetry scheme. To this end state vectors are defined and the quark additivity principle is taken into account. (author)

  1. Moment methods for nonlinear maps

    International Nuclear Information System (INIS)

    Pusch, G.D.; Atomic Energy of Canada Ltd., Chalk River, ON

    1993-01-01

    It is shown that Differential Algebra (DA) may be used to push moments of distributions through a map, at a computational cost per moment comparable to pushing a single particle. The algorithm is independent of order, and whether or not the map is symplectic. Starting from the known result that moment-vectors transform linearly - like a tensor - even under a nonlinear map, I suggest that the form of the moment transformation rule indicates that the moment-vectors are elements of the dual to DA-vector space. I propose several methods of manipulating moments and constructing invariants using DA. I close with speculations on how DA might be used to ''close the circle'' to solve the inverse moment problem, yielding an entirely DA-and-moment-based space-charge code. (Author)

  2. Ferromagnetic semiconductor-metal transition in heterostructures of europium monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Stollenwerk, Tobias; Kroha, Johann [Physikalisches Institut der Universitaet Bonn (Germany)

    2012-07-01

    Experiments on thin films of electron doped europium monoxide show a simultaneous ferromagnetic semiconductor-metal transition which goes along with a huge drop in resistivity over several orders of magnitude. Therefore, this material is a very promising candidate for spintronics applications. We have developed a theory which correctly predicts the simultaneous phase transition in thin films of electron doped EuO and the increase of the Curie temperature T{sub C} with doping concentration. The origin of the increased T{sub C} lies in the enhanced RKKY interaction between the localized 4f moments of the Eu atoms. Therefore, the phase transition is controlled by the population of the conduction band. We investigate the influence of film thickness and interface effects on the population of the conduction band and on the magnetic and electronic properties of the EuO film.

  3. Ferromagnetic semiconductor-metal transition in europium monoxide

    Energy Technology Data Exchange (ETDEWEB)

    Arnold, M.

    2007-10-15

    We present a microscopical model to describe the simultaneous para-to-ferromagnetic and semiconductor-to-metal transition in electron-doped EuO. The physical properties of the model are systematically studied, whereas the main remark is on the interplay between magnetic order and the transport properties. The theory correctly describes detailed experimental features of the conductivity and of the magnetization, obtained for EuO{sub 1-x} or Gd-doped Gd{sub x}Eu{sub 1-x}0. In particular the doping dependence of the Curie temperature is reproduced The existence of correlation-induced local moments on the impurity sites is essential for this description. (orig.)

  4. Half-metallic ferromagnetism in Fe-doped Zn3P2 from first-principles calculations

    International Nuclear Information System (INIS)

    Jaiganesh, G.; Jaya, S. Mathi

    2014-01-01

    Using the first-principles calculations based on the density functional theory, we have studied the magnetism and electronic structure of Fe-doped Zinc Phosphide (Zn 3 P 2 ). Our results show that the half-metallic ground state and ferromagnetic stability for the small Fe concentrations considered in our study. The stability of the doped material has been studied by calculating the heat of formation and analyzing the minimum total energies in nonmagnetic and ferromagnetic phases. A large value of the magnetic moment is obtained from our calculations and our calculation suggests that the Fe-doped Zn 3 P 2 may be a useful material in semiconductor spintronics

  5. Enhanced room temperature ferromagnetism in antiferromagnetic NiO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ravikumar, Patta; Kisan, Bhagaban; Perumal, A., E-mail: perumal@iitg.ernet.in [Department of Physics, Indian institute of Technology Guwahati, Guwahati 781 039 (India)

    2015-08-15

    We report systematic investigations of structural, vibrational, resonance and magnetic properties of nanoscale NiO powders prepared by ball milling process under different milling speeds for 30 hours of milling. Structural properties revealed that both pure NiO and as-milled NiO powders exhibit face centered cubic structure, but average crystallite size decreases to around 11 nm along with significant increase in strain with increasing milling speed. Vibrational properties show the enhancement in the intensity of one-phonon longitudinal optical (LO) band and disappearance of two-magnon band due to size reduction. In addition, two-phonon LO band exhibits red shift due to size-induced phonon confinement effect and surface relaxation. Pure NiO powder exhibit antiferromagnetic nature, which transforms into induced ferromagnetic after size reduction. The average magnetization at room temperature increases with decreasing the crystallite size and a maximum moment of 0.016 μ{sub B}/f.u. at 12 kOe applied field and coercivity of 170 Oe were obtained for 30 hours milled NiO powders at 600 rotation per minute milling speed. The change in the magnetic properties is also supported by the vibrational properties. Thermomagnetization measurements at high temperature reveal a well-defined magnetic phase transition at high temperature (T{sub C}) around 780 K due to induced ferromagnetic phase. Electron paramagnetic resonance (EPR) studies reveal a good agreement between the EPR results and magnetic properties. The observed results are described on the basis of crystallite size variation, defect density, large strain, oxidation/reduction of Ni and interaction between uncompensated surfaces and particle core with lattice expansion. The obtained results suggest that nanoscale NiO powders with high T{sub C} and moderate magnetic moment at room temperature with cubic structure would be useful to expedite for spintronic devices.

  6. Enhanced room temperature ferromagnetism in antiferromagnetic NiO nanoparticles

    Directory of Open Access Journals (Sweden)

    Patta Ravikumar

    2015-08-01

    Full Text Available We report systematic investigations of structural, vibrational, resonance and magnetic properties of nanoscale NiO powders prepared by ball milling process under different milling speeds for 30 hours of milling. Structural properties revealed that both pure NiO and as-milled NiO powders exhibit face centered cubic structure, but average crystallite size decreases to around 11 nm along with significant increase in strain with increasing milling speed. Vibrational properties show the enhancement in the intensity of one-phonon longitudinal optical (LO band and disappearance of two-magnon band due to size reduction. In addition, two-phonon LO band exhibits red shift due to size-induced phonon confinement effect and surface relaxation. Pure NiO powder exhibit antiferromagnetic nature, which transforms into induced ferromagnetic after size reduction. The average magnetization at room temperature increases with decreasing the crystallite size and a maximum moment of 0.016 μB/f.u. at 12 kOe applied field and coercivity of 170 Oe were obtained for 30 hours milled NiO powders at 600 rotation per minute milling speed. The change in the magnetic properties is also supported by the vibrational properties. Thermomagnetization measurements at high temperature reveal a well-defined magnetic phase transition at high temperature (TC around 780 K due to induced ferromagnetic phase. Electron paramagnetic resonance (EPR studies reveal a good agreement between the EPR results and magnetic properties. The observed results are described on the basis of crystallite size variation, defect density, large strain, oxidation/reduction of Ni and interaction between uncompensated surfaces and particle core with lattice expansion. The obtained results suggest that nanoscale NiO powders with high TC and moderate magnetic moment at room temperature with cubic structure would be useful to expedite for spintronic devices.

  7. Paul Callaghan luminous moments

    CERN Document Server

    Callaghan, Paul

    2013-01-01

    Acknowledged internationally for his ground-breaking scientific research in the field of magnetic resonance, Sir Paul Callaghan was a scientist and visionary with a rare gift for promoting science to a wide audience. He was named New Zealander of the Year in 2011. His death in early 2012 robbed New Zealand of an inspirational leader. Paul Callaghan: Luminous Moments brings together some of his most significant writing. Whether he describes his childhood in Wanganui, reflects on discovering the beauty of science, sets out New Zealand's future potential or discusses the experience of fa

  8. Neutron Electric Dipole Moment

    International Nuclear Information System (INIS)

    Mischke, R.E.

    2003-01-01

    The status of experiments to measure the electric dipole moment of the neutron is presented and the planned experiment at Los Alamos is described. The goal of this experiment is an improvement in sensitivity of a factor of 50 to 100 over the current limit. It has the potential to reveal new sources of T and CP violation and to challenge calculations that propose extensions to the Standard Model. The experiment employs several advances in technique to reach its goals and the feasibility of meeting these technical challenges is currently under study

  9. Spin-orbit torques in locally and globally noncentrosymmetric crystals: Antiferromagnets and ferromagnets

    KAUST Repository

    Železný, J.

    2017-01-10

    One of the main obstacles that prevents practical applications of antiferromagnets is the difficulty of manipulating the magnetic order parameter. Recently, following the theoretical prediction [J. Železný, Phys. Rev. Lett. 113, 157201 (2014)]PRLTAO0031-900710.1103/PhysRevLett.113.157201, the electrical switching of magnetic moments in an antiferromagnet was demonstrated [P. Wadley, Science 351, 587 (2016)]SCIEAS0036-807510.1126/science.aab1031. The switching is due to the so-called spin-orbit torque, which has been extensively studied in ferromagnets. In this phenomena a nonequilibrium spin-polarization exchange coupled to the ordered local moments is induced by current, hence exerting a torque on the order parameter. Here we give a general systematic analysis of the symmetry of the spin-orbit torque in locally and globally noncentrosymmetric crystals. We study when the symmetry allows for a nonzero torque, when is the torque effective, and its dependence on the applied current direction and orientation of magnetic moments. For comparison, we consider both antiferromagnetic and ferromagnetic orders. In two representative model crystals we perform microscopic calculations of the spin-orbit torque to illustrate its symmetry properties and to highlight conditions under which the spin-orbit torque can be efficient for manipulating antiferromagnetic moments.

  10. Spin-orbit torques in locally and globally noncentrosymmetric crystals: Antiferromagnets and ferromagnets

    KAUST Repository

    Železný , J.; Gao, H.; Manchon, Aurelien; Freimuth, Frank; Mokrousov, Yuriy; Zemen, J.; Mašek, J.; Sinova, Jairo; Jungwirth, T.

    2017-01-01

    One of the main obstacles that prevents practical applications of antiferromagnets is the difficulty of manipulating the magnetic order parameter. Recently, following the theoretical prediction [J. Železný, Phys. Rev. Lett. 113, 157201 (2014)]PRLTAO0031-900710.1103/PhysRevLett.113.157201, the electrical switching of magnetic moments in an antiferromagnet was demonstrated [P. Wadley, Science 351, 587 (2016)]SCIEAS0036-807510.1126/science.aab1031. The switching is due to the so-called spin-orbit torque, which has been extensively studied in ferromagnets. In this phenomena a nonequilibrium spin-polarization exchange coupled to the ordered local moments is induced by current, hence exerting a torque on the order parameter. Here we give a general systematic analysis of the symmetry of the spin-orbit torque in locally and globally noncentrosymmetric crystals. We study when the symmetry allows for a nonzero torque, when is the torque effective, and its dependence on the applied current direction and orientation of magnetic moments. For comparison, we consider both antiferromagnetic and ferromagnetic orders. In two representative model crystals we perform microscopic calculations of the spin-orbit torque to illustrate its symmetry properties and to highlight conditions under which the spin-orbit torque can be efficient for manipulating antiferromagnetic moments.

  11. Inhomogeneous superconductivity in a ferromagnet

    International Nuclear Information System (INIS)

    Kontos, T.; Aprili, M.; Lesueur, J.; Genet, F.; Boursier, R.; Grison, X.

    2003-01-01

    We have studied a new superconducting state where the condensate wave function resulting from conventional pairing, is modified by an exchange field. Superconductivity is induced into a ferromagnetic thin film (F) by the proximity effect with a superconducting reservoir (S). We observed oscillations of the superconducting order parameter induced in F as a function of the distance from the S/F interface. They originate from the finite momentum transfer provided to Cooper pairs by the splitting of the spin up and down bands. We measured the superconducting density of states in F by tunneling spectroscopy and the Josephson critical current when F is coupled with a superconducting counter-electrode. Negative values of the superconducting order parameter are revealed by capsized tunneling spectra in F and a negative Josephson coupling (π-junction)

  12. Intrinsic ferromagnetism in hexagonal boron nitride nanosheets

    Energy Technology Data Exchange (ETDEWEB)

    Si, M. S.; Gao, Daqiang, E-mail: gaodq@lzu.edu.cn, E-mail: xueds@lzu.edu.cn; Yang, Dezheng; Peng, Yong; Zhang, Z. Y.; Xue, Desheng, E-mail: gaodq@lzu.edu.cn, E-mail: xueds@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Liu, Yushen [Jiangsu Laboratory of Advanced Functional Materials and College of Physics and Engineering, Changshu Institute of Technology, Changshu 215500 (China); Deng, Xiaohui [Department of Physics and Electronic Information Science, Hengyang Normal University, Hengyang 421008 (China); Zhang, G. P. [Department of Physics, Indiana State University, Terre Haute, Indiana 47809 (United States)

    2014-05-28

    Understanding the mechanism of ferromagnetism in hexagonal boron nitride nanosheets, which possess only s and p electrons in comparison with normal ferromagnets based on localized d or f electrons, is a current challenge. In this work, we report an experimental finding that the ferromagnetic coupling is an intrinsic property of hexagonal boron nitride nanosheets, which has never been reported before. Moreover, we further confirm it from ab initio calculations. We show that the measured ferromagnetism should be attributed to the localized π states at edges, where the electron-electron interaction plays the role in this ferromagnetic ordering. More importantly, we demonstrate such edge-induced ferromagnetism causes a high Curie temperature well above room temperature. Our systematical work, including experimental measurements and theoretical confirmation, proves that such unusual room temperature ferromagnetism in hexagonal boron nitride nanosheets is edge-dependent, similar to widely reported graphene-based materials. It is believed that this work will open new perspectives for hexagonal boron nitride spintronic devices.

  13. Dipolar ferromagnets and glasses (invited)

    International Nuclear Information System (INIS)

    Rosenbaum, T.F.; Wu, W.; Ellman, B.; Yang, J.; Aeppli, G.; Reich, D.H.

    1991-01-01

    What is the ground state and what are the dynamics of 10 23 randomly distributed Ising spins? We have attempted to answer these questions through magnetic susceptibility, calorimetric, and neutron scattering studies of the randomly diluted dipolar-coupled Ising magnet LiHo x Y 1-x F 4 . The material is ferromagnetic for dipole concentrations at least as low as x=0.46, with a Curie temperature obeying mean-field scaling relative to that of pure LiHoF 4 . In the dilute spin limit, an x=0.045 crystal shows very unusual glassy properties characterized by decreasing barriers to relaxation as T→0. Its properties are consistent with a single low degeneracy ground state with a large gap for excitations. A slightly more concentrated x=0.167 sample, however, supports a complex ground state with no appreciable gap, in accordance with prevailing theories of spin glasses. The underlying causes of such disparate behavior are discussed in terms of random clusters as probed by neutron studies of the x=0.167 sample. In addition to tracing the evolution of the glassy and ferromagnetic states with dipole concentration, we investigate the effects of a transverse magnetic field on the Ising spin glass, LiHo 0.167 Y 0.833 F 4 . The transverse field mixes the eigenfunctions of the ground-state Ising doublet with the otherwise inaccessible excited-state levels. We observe a rapid decrease in the characteristic relaxation times, large changes in the spectral form of the relaxation, and a depression of the spin-glass transition temperature with the addition of quantum fluctuations

  14. Moments in time

    Directory of Open Access Journals (Sweden)

    Marc eWittmann

    2011-10-01

    Full Text Available It has been suggested that perception and action can be understood as evolving in temporal epochs or sequential processing units. Successive events are fused into units forming a unitary experience or ‘psychological present’. Studies have identified several temporal integration levels on different time scales which are fundamental for our understanding of behaviour and subjective experience. In recent literature concerning the philosophy and neuroscience of consciousness these separate temporal processing levels are not always precisely distinguished. Therefore, empirical evidence from psychophysics and neuropsychology on these distinct temporal processing levels is presented and discussed within philosophical conceptualizations of time experience. On an elementary level, one can identify a functional moment, a basic temporal building block of perception in the range of milliseconds that defines simultaneity and succession. Below a certain threshold temporal order is not perceived, individual events are processed as co-temporal. On a second level, an experienced moment, which is based on temporal integration of up to a few seconds, has been reported in many qualitatively different experiments in perception and action. It has been suggested that this segmental processing mechanism creates temporal windows that provide a logistical basis for conscious representation and the experience of nowness. On a third level of integration, continuity of experience is enabled by working-memory in the range of multiple seconds allowing the maintenance of cognitive operations and emotional feelings, leading to mental presence, a temporal window of an individual’s experienced presence.

  15. Dynamically fluctuating electric dipole moments in fullerene-based magnets.

    Science.gov (United States)

    Kambe, Takashi; Oshima, Kokichi

    2014-09-19

    We report here the direct evidence of the existence of a permanent electric dipole moment in both crystal phases of a fullerene-based magnet--the ferromagnetic α-phase and the antiferromagnetic α'-phase of tetra-kis-(dimethylamino)-ethylene-C60 (TDAE-C60)--as determined by dielectric measurements. We propose that the permanent electric dipole originates from the pairing of a TDAE molecule with surrounding C60 molecules. The two polymorphs exhibit clear differences in their dielectric responses at room temperature and during the freezing process with dynamically fluctuating electric dipole moments, although no difference in their room-temperature structures has been previously observed. This result implies that two polymorphs have different local environment around the molecules. In particular, the ferromagnetism of the α-phase is founded on the homogeneous molecule displacement and orientational ordering. The formation of the different phases with respect to the different rotational states in the Jahn-Teller distorted C60s is also discussed.

  16. The half-metallic ferromagnetism character in Be1−xVxY (Y=Se and Te) alloys: An ab-initio study

    International Nuclear Information System (INIS)

    Sajjad, M.; Manzoor, Sadia; Zhang, H.X.; Noor, N.A.; Alay-e-Abbas, S.M.; Shaukat, A.; Khenata, R.

    2015-01-01

    Ab-initio calculations for V-doped BeSe and BeTe semiconductors are performed by means of all-electrons full-potential linearized augmented plane wave plus local orbital (FP-LAPW+lo) method. The structural properties are optimized using the Wu-Cohen generalized gradient approximation functional, whereas modified Becke and Jhonson local density approximation functional has been employed for evaluating the spin-polarized electronic and magnetic properties. Magnetic stability at various doping concentrations in ferromagnetic (FM) and anti-ferromagnetic (AFM) ordering is investigated by comparing the minimum total energies and enthalpies of formation (ΔH). Studied band structures, density of states, total energy, exchange interactions and magnetic moments manifest both alloys with half-metallic ferromagnetic behavior. Moreover, their valance bands are found to be paired ferromagnetically with V atoms. Furthermore, it was observed that the magnetic moment of vanadium atom reduces from free space charge value due to p–d hybridization which yields small magnetic moments on the Be, Se and Te sites. - Highlights: • Density functional calculations for V-doped BeSe and BeTe are performed. • V-doped BeSe and BeTe are found to be stable half-metallic ferromagnetism. • Improved electronic properties are achieved using mBJLDA which confirm HMF. • The half-metallic gaps show non-linear variation with increasing dopant concentration

  17. Coherent magnon optics in a ferromagnetic spinor Bose-Einstein condensate.

    Science.gov (United States)

    Marti, G Edward; MacRae, Andrew; Olf, Ryan; Lourette, Sean; Fang, Fang; Stamper-Kurn, Dan M

    2014-10-10

    We measure the dispersion relation, gap, and magnetic moment of a magnon in the ferromagnetic F = 1 spinor Bose-Einstein condensate of (87)Rb. From the dispersion relation we measure an average effective mass 1.033(2)(stat)(10)(sys) times the atomic mass, as determined by interfering standing and running coherent magnon waves within the dense and trapped condensed gas. The measured mass is higher than theoretical predictions of mean-field and beyond-mean-field Beliaev theory for a bulk spinor Bose gas with s-wave contact interactions. We observe a magnon energy gap of h × 2.5(1)(stat)(2)(sys) Hz, which is consistent with the predicted effect of magnetic dipole-dipole interactions. These dipolar interactions may also account for the high magnon mass. The effective magnetic moment of -1.04(2)(stat)(8)(sys) times the atomic magnetic moment is consistent with mean-field theory.

  18. Heat dissipation due to ferromagnetic resonance in a ferromagnetic metal monitored by electrical resistance measurement

    International Nuclear Information System (INIS)

    Yamanoi, Kazuto; Yokotani, Yuki; Kimura, Takashi

    2015-01-01

    The heat dissipation due to the resonant precessional motion of the magnetization in a ferromagnetic metal has been investigated. We demonstrated that the temperature during the ferromagnetic resonance can be simply detected by the electrical resistance measurement of the Cu strip line in contact with the ferromagnetic metal. The temperature change of the Cu strip due to the ferromagnetic resonance was found to exceed 10 K, which significantly affects the spin-current transport. The influence of the thermal conductivity of the substrate on the heating was also investigated

  19. High-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb

    International Nuclear Information System (INIS)

    Tu, Nguyen Thanh; Hai, Pham Nam; Anh, Le Duc; Tanaka, Masaaki

    2016-01-01

    We show high-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga_1_−_x,Fe_x)Sb (x = 23% and 25%) thin films grown by low-temperature molecular beam epitaxy. Magnetic circular dichroism spectroscopy and anomalous Hall effect measurements indicate intrinsic ferromagnetism of these samples. The Curie temperature reaches 300 K and 340 K for x = 23% and 25%, respectively, which are the highest values reported so far in intrinsic III-V ferromagnetic semiconductors.

  20. High-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga,Fe)Sb

    Energy Technology Data Exchange (ETDEWEB)

    Tu, Nguyen Thanh [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physics, Ho Chi Minh City University of Pedagogy, 280, An Duong Vuong Street, District 5, Ho Chi Minh City 748242 (Viet Nam); Hai, Pham Nam [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Department of Physical Electronics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro, Tokyo 152-0033 (Japan); Center for Spintronics Research Network (CSRN), The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan); Anh, Le Duc [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Tanaka, Masaaki [Department of Electrical Engineering and Information Systems, The University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo 113-8656 (Japan); Center for Spintronics Research Network (CSRN), The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

    2016-05-09

    We show high-temperature ferromagnetism in heavily Fe-doped ferromagnetic semiconductor (Ga{sub 1−x},Fe{sub x})Sb (x = 23% and 25%) thin films grown by low-temperature molecular beam epitaxy. Magnetic circular dichroism spectroscopy and anomalous Hall effect measurements indicate intrinsic ferromagnetism of these samples. The Curie temperature reaches 300 K and 340 K for x = 23% and 25%, respectively, which are the highest values reported so far in intrinsic III-V ferromagnetic semiconductors.

  1. Itinerant ferromagnetism in actinide 5 f -electron systems: Phenomenological analysis with spin fluctuation theory

    Science.gov (United States)

    Tateiwa, Naoyuki; Pospíšil, Jiří; Haga, Yoshinori; Sakai, Hironori; Matsuda, Tatsuma D.; Yamamoto, Etsuji

    2017-07-01

    We have carried out an analysis of magnetic data in 69 uranium, 7 neptunium, and 4 plutonium ferromagnets with the spin fluctuation theory developed by Takahashi [Y. Takahashi, J. Phys. Soc. Jpn. 55, 3553 (1986), 10.1143/JPSJ.55.3553]. The basic and spin fluctuation parameters of the actinide ferromagnets are determined and the applicability of the spin fluctuation theory to actinide 5 f system has been discussed. Itinerant ferromagnets of the 3 d transition metals and their intermetallics follow a generalized Rhodes-Wohlfarth relation between peff/ps and TC/T0 , viz., peff/ps∝(TC/T0) -3 /2 . Here, ps, peff, TC, and T0 are the spontaneous and effective magnetic moments, the Curie temperature, and the width of spin fluctuation spectrum in energy space, respectively. The same relation is satisfied for TC/T0uranium and neptunium ferromagnets below (TC/T0)kink=0.32 ±0.02 , where a kink structure appears in relation between the two quantities. ps increases more weakly above (TC/T0)kink. A possible interpretation with the TC/T0 dependence of ps is given.

  2. Quantum spin and charge pumping through double quantum dots with ferromagnetic leads

    Energy Technology Data Exchange (ETDEWEB)

    Pan, Hui, E-mail: hpan@buaa.edu.cn [Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Key Laboratory of Micro-Nano Measurement-Manipulation and Physics (Ministry of Education), Beihang University, Beijing 100191 (China); Chen, Ziyu; Zhao, Sufen [Department of Physics, Beijing University of Aeronautics and Astronautics, Beijing 100191 (China); Lue, Rong [Department of Physics, Tsinghua University, Beijing 100084 (China)

    2011-06-06

    The pumping of electrons through double quantum dots (DQDs) attached to ferromagnetic leads have been theoretically investigated by using the nonequilibrium Green's function method. It is found that an oscillating electric field applied to the quantum dot may give rise to the pumped charge and spin currents. In the case that both leads are ferromagnet, a pure spin current can be generated in the antiparallel magnetization configuration, where no net charge current exists. The possibility of manipulating the pumped spin current is explored by tuning the dot level and the ac field. By making use of various tunings, the magnitude and direction of the pumped spin current can be well controlled. For the case that only one lead is ferromagnetic, both of the charge and spin currents can be pumped and flow in opposite directions on the average. The control of the magnitude and direction of the pumped charge and spin currents is also discussed by means of the magnetic flux threading through the DQD ring. -- Highlights: → We theoretically investigate the pumping of electrons through double quantum dots attached to ferromagnetic leads. → An oscillating electric field applied to the quantum dot may give rise to the pumped charge and spin currents. → When both leads are ferromagnet, a pure spin current can be generated in the antiparallel magnetization configuration. → By making use of various tunings, the magnitude and direction of the pumped spin current can be well controlled. → When only one lead is ferromagnetic, both of the charge and spin currents can be pumped and flow in opposite directions.

  3. Approximating distributions from moments

    Science.gov (United States)

    Pawula, R. F.

    1987-11-01

    A method based upon Pearson-type approximations from statistics is developed for approximating a symmetric probability density function from its moments. The extended Fokker-Planck equation for non-Markov processes is shown to be the underlying foundation for the approximations. The approximation is shown to be exact for the beta probability density function. The applicability of the general method is illustrated by numerous pithy examples from linear and nonlinear filtering of both Markov and non-Markov dichotomous noise. New approximations are given for the probability density function in two cases in which exact solutions are unavailable, those of (i) the filter-limiter-filter problem and (ii) second-order Butterworth filtering of the random telegraph signal. The approximate results are compared with previously published Monte Carlo simulations in these two cases.

  4. Coexistence of Superconductivity and Ferromagnetism in ...

    African Journals Online (AJOL)

    KBHEEMA

    Ferromagnetic alignment can be expected to be strongly opposed by superconductivity. .... To obtain temperature dependent of energy gap of equation (23), we used the same techniques to solve the integral .... band metal ZrZn2. Nature, 412: ...

  5. Ferromagnetic and twin domains in LCMO manganites

    International Nuclear Information System (INIS)

    Jung, G.; Markovich, V.; Mogilyanski, D.; Beek, C. van der; Mukovskii, Y.M.

    2005-01-01

    Ferromagnetic and twin domains in lightly Ca-doped La 1-x Ca x MnO 3 single crystals have been visualized and investigated by means of the magneto-optical technique. Both types of domains became visible below the Curie temperature. The dominant structures seen in applied magnetic field are associated with magneto-crystalline anisotropy and twin domains. In a marked difference to the twin domains which appear only in applied magnetic field, ferromagnetic domains show up in zero applied field and are characterized by oppositely oriented spontaneous magnetization in adjacent domains. Ferromagnetic domains take form of almost periodic, corrugated strip-like structures. The corrugation of the ferromagnetic domain pattern is enforced by the underlying twin domains

  6. Planning of nets

    International Nuclear Information System (INIS)

    Carberry, M

    1996-01-01

    The paper is about the planning of nets in areas of low density like it is the case of the rural areas. The author includes economic and technological aspects, planning of nets, demands and management among others

  7. Annotating Coloured Petri Nets

    DEFF Research Database (Denmark)

    Lindstrøm, Bo; Wells, Lisa Marie

    2002-01-01

    Coloured Petri nets (CP-nets) can be used for several fundamentally different purposes like functional analysis, performance analysis, and visualisation. To be able to use the corresponding tool extensions and libraries it is sometimes necessary to include extra auxiliary information in the CP......-net. An example of such auxiliary information is a counter which is associated with a token to be able to do performance analysis. Modifying colour sets and arc inscriptions in a CP-net to support a specific use may lead to creation of several slightly different CP-nets – only to support the different uses...... of the same basic CP-net. One solution to this problem is that the auxiliary information is not integrated into colour sets and arc inscriptions of a CP-net, but is kept separately. This makes it easy to disable this auxiliary information if a CP-net is to be used for another purpose. This paper proposes...

  8. Josephson tunnel junctions with ferromagnetic interlayer

    International Nuclear Information System (INIS)

    Weides, M.P.

    2006-01-01

    Superconductivity and ferromagnetism are well-known physical properties of solid states that have been widely studied and long thought about as antagonistic phenomena due to difference in spin ordering. It turns out that the combination of both superconductor and ferromagnet leads to a very rich and interesting physics. One particular example, the phase oscillations of the superconducting order parameter inside the ferromagnet, will play a major role for the devices discussed in this work. In this thesis, I present Josephson junctions with a thin Al 2 O 3 tunnel barrier and a ferromagnetic interlayer, i.e. superconductor-insulator-ferromagnet-superconductor (SIFS) stacks. The fabrication of junctions was optimized regarding the insulation of electrodes and the homogeneity of the current transport. The junctions were either in the 0 or π coupled ground state, depending on the thickness of the ferromagnetic layer and on temperature. The influence of ferromagnetic layer thickness on the transport properties and the coupling (0, π) of SIFS tunnel junctions was studied. Furthermore, using a stepped ferromagnetic layer with well-chosen thicknesses, I obtained the so-called 0-π Josephson junction. At a certain temperature this 0-π junction can be made perfectly symmetric. In this case the ground state corresponds to a vortex of supercurrent creating a magnetic flux which is a fraction of the magnetic flux quantum Φ 0 . Such structures allow to study the physics of fractional vortices and to build various electronic circuits based on them. The SIFS junctions presented here have an exponentially vanishing damping at T → 0. The SIFS technology developed within the framework of this work may be used to construct classical and quantum devices such as oscillators, memory cells and qubits. (orig.)

  9. Josephson tunnel junctions with ferromagnetic interlayer

    Energy Technology Data Exchange (ETDEWEB)

    Weides, M.P.

    2006-07-01

    Superconductivity and ferromagnetism are well-known physical properties of solid states that have been widely studied and long thought about as antagonistic phenomena due to difference in spin ordering. It turns out that the combination of both superconductor and ferromagnet leads to a very rich and interesting physics. One particular example, the phase oscillations of the superconducting order parameter inside the ferromagnet, will play a major role for the devices discussed in this work. In this thesis, I present Josephson junctions with a thin Al{sub 2}O{sub 3} tunnel barrier and a ferromagnetic interlayer, i.e. superconductor-insulator-ferromagnet-superconductor (SIFS) stacks. The fabrication of junctions was optimized regarding the insulation of electrodes and the homogeneity of the current transport. The junctions were either in the 0 or {pi} coupled ground state, depending on the thickness of the ferromagnetic layer and on temperature. The influence of ferromagnetic layer thickness on the transport properties and the coupling (0, {pi}) of SIFS tunnel junctions was studied. Furthermore, using a stepped ferromagnetic layer with well-chosen thicknesses, I obtained the so-called 0-{pi} Josephson junction. At a certain temperature this 0-{pi} junction can be made perfectly symmetric. In this case the ground state corresponds to a vortex of supercurrent creating a magnetic flux which is a fraction of the magnetic flux quantum {phi}{sub 0}. Such structures allow to study the physics of fractional vortices and to build various electronic circuits based on them. The SIFS junctions presented here have an exponentially vanishing damping at T {yields} 0. The SIFS technology developed within the framework of this work may be used to construct classical and quantum devices such as oscillators, memory cells and qubits. (orig.)

  10. Voltage Control of Rare-Earth Magnetic Moments at the Magnetic-Insulator-Metal Interface

    Science.gov (United States)

    Leon, Alejandro O.; Cahaya, Adam B.; Bauer, Gerrit E. W.

    2018-01-01

    The large spin-orbit interaction in the lanthanides implies a strong coupling between their internal charge and spin degrees of freedom. We formulate the coupling between the voltage and the local magnetic moments of rare-earth atoms with a partially filled 4 f shell at the interface between an insulator and a metal. The rare-earth-mediated torques allow the power-efficient control of spintronic devices by electric-field-induced ferromagnetic resonance and magnetization switching.

  11. Topological magnon bands in ferromagnetic star lattice

    International Nuclear Information System (INIS)

    Owerre, S A

    2017-01-01

    The experimental observation of topological magnon bands and thermal Hall effect in a kagomé lattice ferromagnet Cu(1–3, bdc) has inspired the search for topological magnon effects in various insulating ferromagnets that lack an inversion center allowing a Dzyaloshinskii–Moriya (DM) spin–orbit interaction. The star lattice (also known as the decorated honeycomb lattice) ferromagnet is an ideal candidate for this purpose because it is a variant of the kagomé lattice with additional links that connect the up-pointing and down-pointing triangles. This gives rise to twice the unit cell of the kagomé lattice, and hence more interesting topological magnon effects. In particular, the triangular bridges on the star lattice can be coupled either ferromagnetically or antiferromagnetically which is not possible on the kagomé lattice ferromagnets. Here, we study DM-induced topological magnon bands, chiral edge modes, and thermal magnon Hall effect on the star lattice ferromagnet in different parameter regimes. The star lattice can also be visualized as the parent material from which topological magnon bands can be realized for the kagomé and honeycomb lattices in some limiting cases. (paper)

  12. Topological magnon bands in ferromagnetic star lattice.

    Science.gov (United States)

    Owerre, S A

    2017-05-10

    The experimental observation of topological magnon bands and thermal Hall effect in a kagomé lattice ferromagnet Cu(1-3, bdc) has inspired the search for topological magnon effects in various insulating ferromagnets that lack an inversion center allowing a Dzyaloshinskii-Moriya (DM) spin-orbit interaction. The star lattice (also known as the decorated honeycomb lattice) ferromagnet is an ideal candidate for this purpose because it is a variant of the kagomé lattice with additional links that connect the up-pointing and down-pointing triangles. This gives rise to twice the unit cell of the kagomé lattice, and hence more interesting topological magnon effects. In particular, the triangular bridges on the star lattice can be coupled either ferromagnetically or antiferromagnetically which is not possible on the kagomé lattice ferromagnets. Here, we study DM-induced topological magnon bands, chiral edge modes, and thermal magnon Hall effect on the star lattice ferromagnet in different parameter regimes. The star lattice can also be visualized as the parent material from which topological magnon bands can be realized for the kagomé and honeycomb lattices in some limiting cases.

  13. Moment invariants for particle beams

    International Nuclear Information System (INIS)

    Lysenko, W.P.; Overley, M.S.

    1988-01-01

    The rms emittance is a certain function of second moments in 2-D phase space. It is preserved for linear uncoupled (1-D) motion. In this paper, the authors present new functions of moments that are invariants for coupled motion. These invariants were computed symbolically using a computer algebra system. Possible applications for these invariants are discussed. Also, approximate moment invariants for nonlinear motion are presented

  14. Inductive measurements of ferromagnetic resonance

    International Nuclear Information System (INIS)

    Woodward, R.C.; Kennewell, K.; Crew, D.C.; Stamps, R.L.

    2004-01-01

    Full text: The rapid advance in magnetic data storage has driven groundbreaking work in the science that underpins the properties of ferromagnetic materials at high frequencies. Recent work in this area has included the use of precession in order to produce ultra-high speed switching of magnetic elements, the generation of excited dynamical structures by application of inhomogeneous field pulses, and examination of the propagation of localized spin waves. This paper describes explorations of ultra-fast magnetization dynamics being undertaken at The University of Western Australia. We have studied the differences in magnetization dynamics in simple permalloy films when a sample is excited with sharp pulse compared to the to the dynamics generated by the application of a small amplitude continuous wave signal. We have observed a difference in the resonant frequency determined from these two excitations and will propose reasons for the different resonance responses of the system. Using the ultra-fast techniques described above we have measured dynamical properties that are significantly different to the static properties. These results are explained by the dynamical measurements being made on time scales smaller than the characteristic relaxation time. Future applications of these devices will be to examine broadening of line widths and frequency shifts associated with the excitation of magnetostatic modes, factors limiting quasiballistic reversal and differences between the dynamic and static properties of magnetic materials

  15. Room-temperature ferromagnetism observed in C-/N-/O-implanted MgO single crystals

    Science.gov (United States)

    Li, Qiang; Ye, Bonian; Hao, Yingping; Liu, Jiandang; Zhang, Jie; Zhang, Lijuan; Kong, Wei; Weng, Huimin; Ye, Bangjiao

    2013-01-01

    MgO single crystals were implanted with 70 keV C/N/O ions at room temperature with respective doses of 2 × 1016 and 2 × 1017 ions/cm2. All samples with high-dose implantation showed room temperature hysteresis in magnetization loops. Magnetization and slow positron annihilation measurements confirmed that room temperature ferromagnetism in O-implanted samples was attributed to the presence of Mg vacancies. Furthermore, the introduction of C or N played more effective role in ferromagnetic performance than Mg vacancies. Moreover, the magnetic moment possibly occurred from the localized wave function of unpaired electrons and the exchange interaction formed a long-range magnetic order.

  16. Structural Aspects LiNbO3 Nanoparticles and Their Ferromagnetic Properties

    Science.gov (United States)

    Diaz-Moreno, Carlos A.; Farias-Mancilla, Rurik; Elizalde-Galindo, Jose T.; González-Hernández, Jesus; Hurtado-Macias, Abel; Bahena, Daniel; José-Yacamán, Miguel; Ramos, Manuel

    2014-01-01

    We present a solid-state synthesis of ferromagnetic lithium niobate nanoparticles (LiNbO3) and their corresponding structural aspects. In order to investigate the effect of heat treatments, two batches of samples with a heat-treated (HT) and non-heat-treated (nHT) reduction at 650 °C in 5% of hydrogen/argon were considered to investigate the multiferroic properties and their corresponding structural aspects; using magnetometry and scanning transmission electron microscopy (STEM). Results indicate the existence of ferromagnetic domains with a magnetic moment per unit cell of 5.24 × 10−3 μB; caused mainly due to voids and defects on the nanoparticle surface, as confirmed by STEM measurements. PMID:28788242

  17. Half-metallic ferromagnetism in nitrogen - doped ionic insulator (Li2O): a DFT study

    International Nuclear Information System (INIS)

    Eithiraj, R.D.; Kalpana, G.

    2010-01-01

    The tight binding linear muffin-tin orbital (TB-LMTO) method, is used to study the electronic structure and magnetism in nitrogen - doped Li 2 O (antifluorite - CaF 2 structure). Total energy calculations show that the antifluorite ferromagnetic state is more stable than the antifluorite non-magnetic state at equilibrium volume. Ground state properties such as equilibrium lattice constant and bulk modulus were calculated. The calculations reveal that non-magnetic impurities can induce stable half-metallic ferromagnetic ground state in Li 2 O. The magnetic moment of nitrogen doped Li 2 O can be tuned over a range between 1.00 μ B and 3.00 μ B by changing the concentration of nitrogen from 25% to 75%. (author)

  18. Anisotropy of the Faraday effect in the weak ferromagnet YFeO3

    International Nuclear Information System (INIS)

    Zenkov, A.V.; Krichevtsov, B.B.; Moskvin, A.S.; Mukimov, K.M.; Pisarev, R.V.; Ruvinshtein, M.M.

    1989-01-01

    An experimental investigation was made of the magnetic-field dependence of the Faraday effect in a weak ferromagnet YFeO 3 at the wavelength λ = 0.63 μm. Measurements were made for different orientations of the direction of light propagation k and of the magnetic field H. Changes in the Faraday effect in the k parallel c, H parallel a case were not proportional to changes in the component of the magnetic moment m z . A phenomenological description of the Faraday effect in YFeO 3 was used to separate the ferromagnetic, antiferromagnetic, and diamagnetic contributions to the effect. The antiferromagnetic contribution dominating the Faraday effect was strongly anisotropic. A theoretical analysis was made of the microscopic Faraday effect mechanisms in YFeO 3 using the example of a dipole-allowed transition 6 A 1g → 6 T 1u

  19. Ti{sub 3}CrCu{sub 4}: A possible 2-D ferromagnetic spin fluctuating system

    Energy Technology Data Exchange (ETDEWEB)

    Dhar, S. K.; Kulkarni, R.; Goyal, Neeraj [Department of Condensed Matter Physics & Materials Science, T.I.F.R., Homi Bhabha Road, Colaba, Mumbai, 400005 (India); Provino, A.; Manfrinetti, P. [Department of Chemistry, University of Genova, Via Dodecaneso 31, 16146 Genova (Italy); Paudyal, D. [The Ames Laboratory, US Department of Energy, Iowa State University, Ames, IA 50011-3020 (United States)

    2016-05-15

    Ti{sub 3}CrCu{sub 4} is a new ternary compound which crystallizes in the tetragonal Ti{sub 3}Pd{sub 5} structure type. The Cr atoms form square nets in the a-b plane (a = 3.124 Å) which are separated by an unusually large distance c = 11.228 Å along the tetragonal axis, thus forming a -2-D Cr-sublattice. The paramagnetic susceptibility is characterized by a low effective moment, μ{sub eff} = 1.1 μ{sub B}, a low paramagnetic Curie temperature θ{sub P} (below 7 K) and a temperature independent χ{sub 0} = 6.7 x 10{sup −4} emu/mol. The magnetization at 1.8 K increases rapidly with field nearly saturating to 0.2 μ{sub B}/f.u. The zero field heat capacity C/T shows an upturn below 7 K (∼190 mJ/mol K{sup 2} at ∼0.1K) which is suppressed in applied magnetic fields and interpreted as suggesting the presence of spin fluctuations. The resistivity at low temperatures shows non-Fermi liquid behavior. Overall, the experimental data thus reveal an unusual magnetic state in Ti{sub 3}CrCu{sub 4}, which likely has its origin in the layered nature of the Cr sub-lattice and ferromagnetic spin fluctuations. Density functional theoretical calculations reveal a sharp Cr density of states peak just above the Fermi level, indicating the propensity of Ti{sub 3}CrCu{sub 4} to become magnetic.

  20. Ultra-high sensitivity moment magnetometry of geological samples using magnetic microscopy

    Science.gov (United States)

    Lima, Eduardo A.; Weiss, Benjamin P.

    2016-09-01

    Useful paleomagnetic information is expected to be recorded by samples with moments up to three orders of magnitude below the detection limit of standard superconducting rock magnetometers. Such samples are now detectable using recently developed magnetic microscopes, which map the magnetic fields above room-temperature samples with unprecedented spatial resolutions and field sensitivities. However, realizing this potential requires the development of techniques for retrieving sample moments from magnetic microscopy data. With this goal, we developed a technique for uniquely obtaining the net magnetic moment of geological samples from magnetic microscopy maps of unresolved or nearly unresolved magnetization. This technique is particularly powerful for analyzing small, weakly magnetized samples such as meteoritic chondrules and terrestrial silicate crystals like zircons. We validated this technique by applying it to field maps generated from synthetic sources and also to field maps measured using a superconducting quantum interference device (SQUID) microscope above geological samples with moments down to 10-15 Am2. For the most magnetic rock samples, the net moments estimated from the SQUID microscope data are within error of independent moment measurements acquired using lower sensitivity standard rock magnetometers. In addition to its superior moment sensitivity, SQUID microscope net moment magnetometry also enables the identification and isolation of magnetic contamination and background sources, which is critical for improving accuracy in paleomagnetic studies of weakly magnetic samples.

  1. First-principles study on half-metallic ferromagnetic properties of Zn1- x V x Se ternary alloys

    Science.gov (United States)

    Khatta, Swati; Tripathi, S. K.; Prakash, Satya

    2017-09-01

    The spin-polarised density functional theory along with self-consistent plane-wave pseudopotential is used to investigate the half-metallic ferromagnetic properties of ternary alloys Zn1- x V x Se. The generalized gradient approximation is used for exchange-correlation potential. The equilibrium lattice constants, bulk modulus, and its derivatives are calculated. The calculated spin-polarised energy-band structures reveal that these alloys are half-metallic for x = 0.375 and 0.50 and nearly half-metallic for other values of x. The estimated direct and indirect bandgaps may be useful for the magneto-optical absorption experiments. It is found that there is strong Zn 4s, Se 4p, and V 3d orbital hybridization in the conduction bands of both the spins, while Se 4p and V 3d orbital hybridization predominates in the valence bands of both the spins. The s, p-d, and p-d orbital hybridization reduces the local magnetic moment of V atoms and small local magnetic moments are produced on Zn and Se atoms which get coupled with V atoms in ferromagnetic and antiferromagnetic phases, respectively. The conduction and valence-band-edge splittings and exchange constants predict the ferromagnetism in these alloys. The conduction band-impurity (s and p-d) exchange interaction is more significant for ferromagnetism in these alloys than the valence band-impurity (p-d) exchange interaction.

  2. Electronic structure of ferromagnetic semiconductor Ga1-xMnxAs probed by sub-gap magneto-optical spectroscopy

    OpenAIRE

    Acbas, G.; Kim, M. -H.; Cukr, M.; Novak, V.; Scarpulla, M. A.; Dubon, O. D.; Jungwirth, T.; Sinova, Jairo; Cerne, J.

    2009-01-01

    We employ Faraday and Kerr effect spectroscopy in the infrared range to investigate the electronic structure of Ga1-xMnxAs near the Fermi energy. The band structure of this archetypical dilute-moment ferromagnetic semiconductor has been a matter of controversy, fueled partly by previous measurements of the unpolarized infrared absorption and their phenomenological impurity-band interpretation. The infrared magneto-optical effects we study arise directly from the spin-splitting of the carrier ...

  3. Half-metallic ferromagnetism in Cu-doped zinc-blende ZnO from first principles study

    International Nuclear Information System (INIS)

    Li, X.F.; Zhang, J.; Xu, B.; Yao, K.L.

    2012-01-01

    Electronic structures and magnetism of Cu-doped zinc-blende ZnO have been investigated by the first-principle method based on density functional theory (DFT). The results show that Cu can induce stable ferromagnetic ground state. The magnetic moment of supercell including single Cu atom is 1.0 μ B . Electronic structure shows that Cu-doped zinc-blende ZnO is a p-type half-metallic ferromagnet. The half-metal property is mainly attribute to the crystal field splitting of Cu 3d orbital, and the ferromagnetism is dominated by the hole-mediated double exchange mechanism. Therefore, Cu-doped zinc-blende ZnO should be useful in semiconductor spintronics and other applications. - Highlights: → Magnetism of Cu-doped zinc-blende ZnO. → Cu-doped zinc-blende ZnO shows interesting half-metal character. → Total energies calculations reveal that Cu can induce ferromagnetic ground state. → Ferromagnetism dominated by the hole-mediated double exchange mechanism.

  4. Face recognition using Krawtchouk moment

    Indian Academy of Sciences (India)

    Zernike moment to enhance the discriminant nature (Pang et al 2006). ... was proposed which is partially invariant to changes in the local image samples, ... tigate the Krawtchouk discrete orthogonal moment-based feature ..... in scale have been achieved by changing the distance between the person and the video camera.

  5. Variational approach to magnetic moments

    Energy Technology Data Exchange (ETDEWEB)

    Lipparini, E; Stringari, S; Traini, M [Dipartimento di Matematica e Fisica, Libera Universita di Trento, Italy

    1977-11-07

    Magnetic moments in nuclei with a spin unsaturated core plus or minus an extra nucleon have been studied using a restricted Hartree-Fock approach. The method yields simple explicit expressions for the deformed ground state and for magnetic moments. Different projection techniques of the HF scheme have been discussed and compared with perturbation theory.

  6. On fractional Fourier transform moments

    NARCIS (Netherlands)

    Alieva, T.; Bastiaans, M.J.

    2000-01-01

    Based on the relation between the ambiguity function represented in a quasi-polar coordinate system and the fractional power spectra, the fractional Fourier transform moments are introduced. Important equalities for the global second-order fractional Fourier transform moments are derived and their

  7. Neutron Electric Dipole Moment Experiments

    OpenAIRE

    Peng, Jen-Chieh

    2008-01-01

    The neutron electric dipole moment (EDM) provides unique information on CP violation and physics beyond the Standard Model. We first review the history of experimental searches for neutron electric dipole moment. The status of future neutron EDM experiments, including experiments using ultra-cold neutrons produced in superfluid helium, will then be presented.

  8. Magnetic Moment of $^{59}$Cu

    CERN Multimedia

    2002-01-01

    Experiment IS358 uses the intense and pure beams of copper isotopes provided by the ISOLDE RILIS (resonance ionization laser ion source). The isotopes are implanted and oriented in the low temperature nuclear orientation set-up NICOLE. Magnetic moments are measured by $\\beta$-NMR. Copper (Z=29), with a single proton above the proton-magic nickel isotopes provides an ideal testground for precise shell model calculations of magnetic moments and their experimental verification. In the course of our experiments we already determined the magnetic moments of $^{67}$Ni, $^{67}$Cu, $^{68g}$Cu, $^{69}$Cu and $^{71}$Cu which provide important information on the magicity of the N=40 subshell closure. In 2001 we plan to conclude our systematic investigations by measuring the magnetic moment of the neutron-deficient isotope $^{59}$Cu. This will pave the way for a subsequent study of the magnetic moment of $^{57}$Cu with a complementary method.

  9. Ferromagnetism and interlayer exchange coupling in thin metallic films

    Energy Technology Data Exchange (ETDEWEB)

    Kienert, Jochen

    2008-07-15

    This thesis is concerned with the ferromagnetic Kondo lattice (s-d,s-f) model for film geometry. The spin-fermion interaction of this model refers to substances in which localized spins interact with mobile charge carriers like in (dilute) magnetic semiconductors, manganites, or rare-earth compounds. The carrier-mediated, indirect interaction between the localized spins comprises the long-range, oscillatory RKKY exchange interaction in the weak-coupling case and the short-range doubleexchange interaction for strong spin-fermion coupling. Both limits are recovered in this work by mapping the problem onto an effective Heisenberg model. The influence of reduced translational symmetry on the effective exchange interaction and on the magnetic properties of the ferromagnetic Kondo lattice model is investigated. Curie temperatures are obtained for different parameter constellations. The consequences of charge transfer and of lattice relaxation on the magnetic stability at the surface are considered. Since the effective exchange integrals are closely related to the electronic structure in terms of the density of states and of the kinetic energy, the discussion is based on the modifications of these quantities in the dimensionally-reduced case. The important role of spin waves for thin film and surface magnetism is demonstrated. Interlayer exchange coupling represents a particularly interesting and important manifestation of the indirect interaction among localized magnetic moments. The coupling between monatomic layers in thin films is studied in the framework of an RKKY approach. It is decisively determined by the type of in-plane and perpendicular dispersion of the charge carriers and is strongly suppressed above a critical value of the Fermi energy. Finally, the temperature-dependent magnetic stability of thin interlayer-coupled films is addressed and the conditions for a temperature-driven magnetic reorientation transition are discussed. (orig.)

  10. Quantum net dynamics

    International Nuclear Information System (INIS)

    Finkelstein, D.

    1989-01-01

    The quantum net unifies the basic principles of quantum theory and relativity in a quantum spacetime having no ultraviolet infinities, supporting the Dirac equation, and having the usual vacuum as a quantum condensation. A correspondence principle connects nets to Schwinger sources and further unifies the vertical structure of the theory, so that the functions of the many hierarchic levels of quantum field theory (predicate algebra, set theory, topology,hor-ellipsis, quantum dynamics) are served by one in quantum net dynamics

  11. On the mechanism of spin-dependent (e,2e) scattering from a ferromagnetic surface

    International Nuclear Information System (INIS)

    Samarin, S N; Sergeant, A D; Pravica, L; Cvejanovic, D; Wilkie, P; Guagliardo, P; Williams, J F; Artamonov, O M; Suvorova, A A

    2009-01-01

    A simple model is suggested for a qualitative analysis of spin-dependent (e,2e) reaction on a ferromagnetic surface. The model is based on the scattering of the primary electron with the average spin projection 1 > by the valence electron with the average spin projection 2 >. To test the model the energy distributions of correlated electron pairs are measured for parallel and anti-parallel orientations of the magnetic moment of the cobalt film and polarization vector of the incident beam. The proposed model explains qualitatively the spin-asymmetry of the measured binding energy spectrum.

  12. Monte Carlo simulations of a ferromagnetic-FeF2 system

    International Nuclear Information System (INIS)

    Billoni, Orlando V.; Tamarit, Francisco A.; Cannas, Sergio A.

    2006-01-01

    In this work, we perform Monte Carlo simulations to study the magnetization reversal mechanism in ferromagnetic thin films on FeF 2 . In particular, we emulate a bilayer AFM/FM structure, where the AFM interface corresponds to an uncompensated (100) plane. The magnetic moments are modeled by classical Heisenberg spin variables. Our analysis focus on the role of the exchange interaction J AF between the FM spins and the spins belonging to the AFM interface on the reversal mechanisms of the magnetization. By simulating hysteresis loops we study the effect of temperature on the bias field

  13. Programming NET Web Services

    CERN Document Server

    Ferrara, Alex

    2007-01-01

    Web services are poised to become a key technology for a wide range of Internet-enabled applications, spanning everything from straight B2B systems to mobile devices and proprietary in-house software. While there are several tools and platforms that can be used for building web services, developers are finding a powerful tool in Microsoft's .NET Framework and Visual Studio .NET. Designed from scratch to support the development of web services, the .NET Framework simplifies the process--programmers find that tasks that took an hour using the SOAP Toolkit take just minutes. Programming .NET

  14. Game Coloured Petri Nets

    DEFF Research Database (Denmark)

    Westergaard, Michael

    2006-01-01

    This paper introduces the notion of game coloured Petri nets. This allows the modeler to explicitly model what parts of the model comprise the modeled system and what parts are the environment of the modeled system. We give the formal definition of game coloured Petri nets, a means of reachability...... analysis of this net class, and an application of game coloured Petri nets to automatically generate easy-to-understand visualizations of the model by exploiting the knowledge that some parts of the model are not interesting from a visualization perspective (i.e. they are part of the environment...

  15. Spectrum of ferromagnetic transition metal magnetic excitations and neutron scattering

    International Nuclear Information System (INIS)

    Kuzemskij, A.L.

    1979-01-01

    Quantum statistical models of ferromagnetic transition metals as well as methods of their solutions are reviewed. The correspondence of results on solving these models and the data on scattering thermal neutrons in ferromagnetic is discussed

  16. On the baryon magnetic moments

    International Nuclear Information System (INIS)

    Ferreira, P.L.

    1976-01-01

    In the context of quark confinement ideas, the baryon magnetic moments are calculated by assuming a SU(3) breaking due to the inequalities of the quark masses (m sub(p) different m sub(n) different m lambda ). The modified SU(6) result for the ratio of the magnetic moments of the neutron and proton is obtained. The p-quark is found heavier than the n-quark by circa 15 MeV. and alternative way of evaluating the baryon magnetic moments by means of simple physical considerations based on the properties of the SU(6) baryon S-waves functions is given

  17. Moment Magnitude discussion in Austria

    Science.gov (United States)

    Weginger, Stefan; Jia, Yan; Hausmann, Helmut; Lenhardt, Wolfgang

    2017-04-01

    We implemented and tested the Moment Magnitude estimation „dbmw" from the University of Trieste in our Antelope near real-time System. It is used to get a fast Moment Magnitude solutions and Ground Motion Parameter (PGA, PGV, PSA 0.3, PSA 1.0 and PSA 3.0) to calculate Shake and Interactive maps. A Moment Magnitude Catalogue was generated and compared with the Austrian Earthquake Catalogue and all available Magnitude solution of the neighbouring agencies. Relations of Mw to Ml and Ground Motion to Intensity are presented.

  18. Magnetic moment of 33Cl

    International Nuclear Information System (INIS)

    Matsuta, K.; Arimura, K.; Nagatomo, T.; Akutsu, K.; Iwakoshi, T.; Kudo, S.; Ogura, M.; Takechi, M.; Tanaka, K.; Sumikama, T.; Minamisono, K.; Miyake, T.; Minamisono, T.; Fukuda, M.; Mihara, M.; Kitagawa, A.; Sasaki, M.; Kanazawa, M.; Torikoshi, M.; Suda, M.; Hirai, M.; Momota, S.; Nojiri, Y.; Sakamoto, A.; Saihara, M.; Ohtsubo, T.; Alonso, J.R.; Krebs, G.F.; Symons, T.J.M.

    2004-01-01

    The magnetic moment of 33 Cl (Iπ=3/2+, T1/2=2.51s) has been re-measured precisely by β-NMR method. The obtained magnetic moment |μ|=0.7549(3)μN is consistent with the old value 0.7523(16)μN, but is 5 times more accurate. The value is well reproduced by the shell model calculation, μSM=0.70μN. Combined with the magnetic moment of the mirror partner 33 S, the nuclear matrix elements , , , and were derived

  19. Moment methods with effective nuclear Hamiltonians; calculations of radial moments

    International Nuclear Information System (INIS)

    Belehrad, R.H.

    1981-02-01

    A truncated orthogonal polynomial expansion is used to evaluate the expectation value of the radial moments of the one-body density of nuclei. The expansion contains the configuration moments, , , and 2 >, where R/sup (k)/ is the operator for the k-th power of the radial coordinate r, and H is the effective nuclear Hamiltonian which is the sum of the relative kinetic energy operator and the Bruckner G matrix. Configuration moments are calculated using trace reduction formulae where the proton and neutron orbitals are treated separately in order to find expectation values of good total isospin. The operator averages are taken over many-body shell model states in the harmonic oscillator basis where all particles are active and single-particle orbitals through six major shells are included. The radial moment expectation values are calculated for the nuclei 16 O, 40 Ca, and 58 Ni and find that is usually the largest term in the expansion giving a large model space dependence to the results. For each of the 3 nuclei, a model space is found which gives the desired rms radius and then we find that the other 5 lowest moments compare favorably with other theoretical predictions. Finally, we use a method of Gordon (5) to employ the lowest 6 radial moment expectation values in the calculation of elastic electron scattering from these nuclei. For low to moderate momentum transfer, the results compare favorably with the experimental data

  20. Ferromagnetic Josephson Junctions for Cryogenic Memory

    Science.gov (United States)

    Niedzielski, Bethany M.; Gingrich, Eric C.; Khasawneh, Mazin A.; Loloee, Reza; Pratt, William P., Jr.; Birge, Norman O.

    2015-03-01

    Josephson junctions containing ferromagnetic materials are of interest for both scientific and technological purposes. In principle, either the amplitude of the critical current or superconducting phase shift across the junction can be controlled by the relative magnetization directions of the ferromagnetic layers in the junction. Our approach concentrates on phase control utilizing two junctions in a SQUID geometry. We will report on efforts to control the phase of junctions carrying either spin-singlet or spin-triplet supercurrent for cryogenic memory applications. Supported by Northorp Grumman Corporation and by IARPA under SPAWAR Contract N66001-12-C-2017.

  1. Giant magnetotransmission and magnetoreflection in ferromagnetic materials

    International Nuclear Information System (INIS)

    Telegin, A.V.; Sukhorukov, Yu.P.; Loshkareva, N.N.; Mostovshchikova, E.V.; Bebenin, N.G.; Gan'shina, E.A.; Granovsky, A.B.

    2015-01-01

    We present a brief review on magnetotransmission (magnetoabsorption) and magnetoreflection of natural (unpolarized) light in ferromagnetic chromium chalcogenide spinel, manganites with perovskite structure and thin-film metallic nanostructures in the middle infrared spectral range. The magnetooptical effects under discussion are of high interest for numerous and promising applications in the infrared optoelectronics. - Highlights: • Magnetotransmission and magnetoreflection of light in ferromagnetic are presented. • The effects are greater than common magnetooptical phenomena in the infrared. • The effects may have a different origin depending on a material or spectral range. • Possible applications of the magnetotransmission and magnetoreflection are discussed

  2. Giant magnetotransmission and magnetoreflection in ferromagnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Telegin, A.V., E-mail: telegin@imp.uran.ru [M.N. Miheev Institute of Metal Physics of Ural Branch of RAS, 620137 Yekaterinburg (Russian Federation); Sukhorukov, Yu.P.; Loshkareva, N.N.; Mostovshchikova, E.V.; Bebenin, N.G. [M.N. Miheev Institute of Metal Physics of Ural Branch of RAS, 620137 Yekaterinburg (Russian Federation); Gan' shina, E.A.; Granovsky, A.B. [Moscow State University, 119991 Moscow (Russian Federation)

    2015-06-01

    We present a brief review on magnetotransmission (magnetoabsorption) and magnetoreflection of natural (unpolarized) light in ferromagnetic chromium chalcogenide spinel, manganites with perovskite structure and thin-film metallic nanostructures in the middle infrared spectral range. The magnetooptical effects under discussion are of high interest for numerous and promising applications in the infrared optoelectronics. - Highlights: • Magnetotransmission and magnetoreflection of light in ferromagnetic are presented. • The effects are greater than common magnetooptical phenomena in the infrared. • The effects may have a different origin depending on a material or spectral range. • Possible applications of the magnetotransmission and magnetoreflection are discussed.

  3. Nonlinear nuclear magnetic resonance in ferromagnets

    International Nuclear Information System (INIS)

    Nurgaliev, T.

    1988-01-01

    The properties of nonlinear nuclear magnetic resonance (NMR) have been studied theoretically by taking into account the interaction between NMR and FMR in the ferromagnets. The Landau-Lifshitz-Bloch equations, describing the electron and nuclear magnetization behaviour in ferromagnets are presented in an integral form for a weakly excited electronic system. The stationary solution of these equations has been analysed in the case of equal NMR and FMR frequencies: the criteria for the appearance of two stable dynamic states is found and the high-frequency magnetic susceptibility for these systems is investigated. 2 figs., 8 refs

  4. Magnetic pinning in superconductor-ferromagnet multilayers

    International Nuclear Information System (INIS)

    Bulaevskii, L. N.; Chudnovsky, E. M.; Maley, M. P.

    2000-01-01

    We argue that superconductor/ferromagnet multilayers of nanoscale period should exhibit strong pinning of vortices by the magnetic domain structure in magnetic fields below the coercive field when ferromagnetic layers exhibit strong perpendicular magnetic anisotropy. The estimated maximum magnetic pinning energy for single vortex in such a system is about 100 times larger than the pinning energy by columnar defects. This pinning energy may provide critical currents as high as 10 6 -10 7 A/cm 2 at high temperatures (but not very close to T c ) at least in magnetic fields below 0.1 T. (c) 2000 American Institute of Physics

  5. Magnetic pinning in superconductor-ferromagnet multilayers

    Energy Technology Data Exchange (ETDEWEB)

    Bulaevskii, L. N. [Department of Physics and Astronomy, CUNY Lehman College 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Chudnovsky, E. M. [Department of Physics and Astronomy, CUNY Lehman College, 250 Bedford Park Boulevard West, Bronx, New York 10468-1589 (United States); Maley, M. P. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

    2000-05-01

    We argue that superconductor/ferromagnet multilayers of nanoscale period should exhibit strong pinning of vortices by the magnetic domain structure in magnetic fields below the coercive field when ferromagnetic layers exhibit strong perpendicular magnetic anisotropy. The estimated maximum magnetic pinning energy for single vortex in such a system is about 100 times larger than the pinning energy by columnar defects. This pinning energy may provide critical currents as high as 10{sup 6}-10{sup 7} A/cm{sup 2} at high temperatures (but not very close to T{sub c}) at least in magnetic fields below 0.1 T. (c) 2000 American Institute of Physics.

  6. Itinerant Ferromagnetism in Ultracold Fermi Gases

    DEFF Research Database (Denmark)

    Heiselberg, Henning

    2012-01-01

    Itinerant ferromagnetism in cold Fermi gases with repulsive interactions is studied applying the Jastrow-Slater approximation generalized to finite polarization and temperature. For two components at zero temperature a second order transition is found at akF ≃ 0.90 compatible with QMC. Thermodyna......Itinerant ferromagnetism in cold Fermi gases with repulsive interactions is studied applying the Jastrow-Slater approximation generalized to finite polarization and temperature. For two components at zero temperature a second order transition is found at akF ≃ 0.90 compatible with QMC...

  7. Proximity effects in ferromagnet/superconductor structures

    International Nuclear Information System (INIS)

    Yu, H.L.; Sun, G.Y.; Yang, L.Y.; Xing, D.Y.

    2004-01-01

    The Nambu spinor Green's function approach is applied to study proximity effects in ferromagnet/superconductor (FM/SC) structures. They include the induced superconducting order parameter and density of states (DOS) with superconducting feature on the FM side, and spin-dependent DOS within the energy gap on the SC side. The latter indicates an appearance of gapless superconductivity and a coexistence of ferromagnetism and superconductivity in a small regime near the interface. The influence of exchange energy in FM and barrier strength at interface on the proximity effects is discussed

  8. Magnon-photon interaction in ferromagnets

    International Nuclear Information System (INIS)

    Shrivastava, K.N.

    1980-01-01

    A magnon-photon interaction for the magnetic vector of the electromagnetic wave perpendicular to the direction of magnetization in a ferromagnet is constructed with the use of Bogoliubov transformation. The resulting magnon-photon interaction is found to contain several interesting new radiation effects. The self-energy of the magnon is calculated and life times arising from the radiation scattering are predicted. The magnon frequency shift due to the radiation field is found. One of the terms arising from the one-magnon one-photon scattering gives a line width that is in reasonable agreement with the experimentally measured value of ferromagnetic resonance line width in yttrium iron garnet. (orig.)

  9. Wellhead with non-ferromagnetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Hinson, Richard A [Houston, TX; Vinegar, Harold J [Bellaire, TX

    2009-05-19

    Wellheads for coupling to a heater located in a wellbore in a subsurface formation are described herein. At least one wellhead may include a heater located in a wellbore in a subsurface formation; and a wellhead coupled to the heater. The wellhead may be configured to electrically couple the heater to one or more surface electrical components. The wellhead may include at least one non-ferromagnetic material such that ferromagnetic effects are inhibited in the wellhead. Systems and methods for using such wellheads for treating a subsurface formation are described herein.

  10. Vortex dynamics in ferromagnetic/superconducting bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Cieplak, M.Z.; Adamus, Z. [Polish Acad Sci, Inst Phys, PL-02668 Warsaw, (Poland); Konczykowski, M. [CEA, DSM, DRECAM, Lab Solides Irradies, Ecole Polytechnique, CNRS-UMR 7642, F-91128 Palaiseau (France); Zhu, L.Y.; Chien, C.L. [Johns Hopkins Univ, Dept Phys and Astron, Baltimore, MD 21218 (United States)

    2008-07-01

    The dependence of vortex dynamics on the geometry of magnetic domain pattern is studied in the superconducting/ferromagnetic bilayers, in which niobium is a superconductor, and Co/Pt multilayer with perpendicular magnetic anisotropy serves as a ferromagnetic layer. Magnetic domain patterns with different density of domains per surface area and different domain size, w, are obtained for Co/Pt with different thickness of Pt. The dense patterns of domains with the size comparable to the magnetic penetration depth (w {>=} {lambda}) produce large vortex pinning and smooth vortex penetration, while less dense patterns with larger domains (w {>=}{>=} {lambda}) enhance pinning less effectively and result in flux jumps during flux motion. (authors)

  11. Temperature limited heater utilizing non-ferromagnetic conductor

    Science.gov (United States)

    Vinegar,; Harold J. , Harris; Kelvin, Christopher [Houston, TX

    2012-07-17

    A heater is described. The heater includes a ferromagnetic conductor and an electrical conductor electrically coupled to the ferromagnetic conductor. The ferromagnetic conductor is positioned relative to the electrical conductor such that an electromagnetic field produced by time-varying current flow in the ferromagnetic conductor confines a majority of the flow of the electrical current to the electrical conductor at temperatures below or near a selected temperature.

  12. The half-metallic ferromagnetism character in Be1-xVxY (Y=Se and Te) alloys: An ab-initio study

    Science.gov (United States)

    Sajjad, M.; Manzoor, Sadia; Zhang, H. X.; Noor, N. A.; Alay-e-Abbas, S. M.; Shaukat, A.; Khenata, R.

    2015-04-01

    Ab-initio calculations for V-doped BeSe and BeTe semiconductors are performed by means of all-electrons full-potential linearized augmented plane wave plus local orbital (FP-LAPW+lo) method. The structural properties are optimized using the Wu-Cohen generalized gradient approximation functional, whereas modified Becke and Jhonson local density approximation functional has been employed for evaluating the spin-polarized electronic and magnetic properties. Magnetic stability at various doping concentrations in ferromagnetic (FM) and anti-ferromagnetic (AFM) ordering is investigated by comparing the minimum total energies and enthalpies of formation (ΔH). Studied band structures, density of states, total energy, exchange interactions and magnetic moments manifest both alloys with half-metallic ferromagnetic behavior. Moreover, their valance bands are found to be paired ferromagnetically with V atoms. Furthermore, it was observed that the magnetic moment of vanadium atom reduces from free space charge value due to p-d hybridization which yields small magnetic moments on the Be, Se and Te sites.

  13. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt

    1991-01-01

    This paper describes how Coloured Petri Nets (CP-nets) have been developed — from being a promising theoretical model to being a full-fledged language for the design, specification, simulation, validation and implementation of large software systems (and other systems in which human beings and...

  14. Net zero water

    CSIR Research Space (South Africa)

    Lindeque, M

    2013-01-01

    Full Text Available the national grid. The unfortunate situation with water is that there is no replacement technology for water. Water can be supplied from many different sources. A net zero energy development will move closer to a net zero water development by reducing...

  15. Construction of monophase nets

    International Nuclear Information System (INIS)

    Suarez A, Jose Antonio

    1996-01-01

    The paper refers to the use of monophase loads in commercial residential urbanizations and in small industries, for this reason it is considered unnecessary the construction of three-phase nets. The author makes a historical recount of these nets in Bogota, his capacities, uses and energy savings

  16. Ferromagnets as pure spin current generators and detectors

    Science.gov (United States)

    Qu, Danru; Miao, Bingfeng; Chien, Chia -Ling; Huang, Ssu -Yen

    2015-09-08

    Provided is a spintronics device. The spintronics can include a ferromagnetic metal layer, a positive electrode disposed on a first surface portion of the ferromagnetic metal layer, and a negative electrode disposed on a second surface portion of the ferromagnetic metal.

  17. Towards ferromagnet/superconductor junctions on graphene

    International Nuclear Information System (INIS)

    Pakkayil, Shijin Babu

    2015-01-01

    Ever since A. Aspect et al. performed the famous 1982 experiment to prove the violation of Bell's inequality, there have been suggestions to conduct the same experiment in a solid state system. Some of those proposals involve superconductors as the source of entangled electron pair and spin depended interfaces as the optical analogue of polariser/filter. Semiconductors can serve as the best medium for such an experiment due to their long relaxation lengths. So far there are no reports on a ferromagnet/superconductor junctions on a semiconductor even though such junctions has been successfully realised in metallic systems. This thesis reports the successful fabrication of ferromagnet/superconductor junction along with characterising measurements in a perfectly two dimensional zero-gap semiconductor known as graphene. Since it's discovery in 2004, graphene has attracted prodigious interest from both academia and industry due to it's inimitable physical properties: very high mobility, high thermal and electrical conductivity, a high Young's modulus and impermeability. Graphene is also expected to have very long spin relaxation length and high spin life time because of it's low spin orbit coupling. For this reason and since researchers are always looking for novel materials and devices to comply with the high demands for better and faster data storage devices, graphene has emanated as a brand new material system for spin based devices. The very first spin injection and detection in graphene was realised in 2007 and ever since, the focal point of the research has been to improve the spin transport properties. A part of this thesis discusses a new fabrication recipe which has a high yield for successfully contacting graphene with a ferromagnet. A high starting yield for ferromagnetic contacts is a irremissible condition for combining superconducting contacts to the device to fabricate ferromagnet/superconductor junctions. Any fabrication recipe

  18. Towards ferromagnet/superconductor junctions on graphene

    Energy Technology Data Exchange (ETDEWEB)

    Pakkayil, Shijin Babu

    2015-07-01

    Ever since A. Aspect et al. performed the famous 1982 experiment to prove the violation of Bell's inequality, there have been suggestions to conduct the same experiment in a solid state system. Some of those proposals involve superconductors as the source of entangled electron pair and spin depended interfaces as the optical analogue of polariser/filter. Semiconductors can serve as the best medium for such an experiment due to their long relaxation lengths. So far there are no reports on a ferromagnet/superconductor junctions on a semiconductor even though such junctions has been successfully realised in metallic systems. This thesis reports the successful fabrication of ferromagnet/superconductor junction along with characterising measurements in a perfectly two dimensional zero-gap semiconductor known as graphene. Since it's discovery in 2004, graphene has attracted prodigious interest from both academia and industry due to it's inimitable physical properties: very high mobility, high thermal and electrical conductivity, a high Young's modulus and impermeability. Graphene is also expected to have very long spin relaxation length and high spin life time because of it's low spin orbit coupling. For this reason and since researchers are always looking for novel materials and devices to comply with the high demands for better and faster data storage devices, graphene has emanated as a brand new material system for spin based devices. The very first spin injection and detection in graphene was realised in 2007 and ever since, the focal point of the research has been to improve the spin transport properties. A part of this thesis discusses a new fabrication recipe which has a high yield for successfully contacting graphene with a ferromagnet. A high starting yield for ferromagnetic contacts is a irremissible condition for combining superconducting contacts to the device to fabricate ferromagnet/superconductor junctions. Any fabrication recipe

  19. Fusion through the NET

    International Nuclear Information System (INIS)

    Spears, B.

    1987-01-01

    The paper concerns the next generation of fusion machines which are intended to demonstrate the technical viability of fusion. In Europe, the device that will follow on from JET is known as NET - the Next European Torus. If the design programme for NET proceeds, Europe could start to build the machine in 1994. The present JET programme hopes to achieve breakeven in the early 1990's. NET hopes to reach ignition in the next century, and so lay the foundation for a demonstration reactor. A description is given of the technical specifications of the components of NET, including: the first wall, the divertors to protect the wall, the array of magnets that provide the fields containing the plasma, the superconducting magnets, and the shield of the machine. NET's research programme is briefly outlined, including the testing programme to optimise conditions in the machine to achieve ignition, and its safety work. (U.K.)

  20. Fast computation of Krawtchouk moments

    Czech Academy of Sciences Publication Activity Database

    Honarvar Shakibaei Asli, B.; Flusser, Jan

    2014-01-01

    Roč. 288, č. 1 (2014), s. 73-86 ISSN 0020-0255 R&D Projects: GA ČR GAP103/11/1552 Institutional support: RVO:67985556 Keywords : Krawtchouk polynomial * Krawtchouk moment * Geometric moment * Impulse response * Fast computation * Digital filter Subject RIV: JD - Computer Applications, Robotics Impact factor: 4.038, year: 2014 http://library.utia.cas.cz/separaty/2014/ZOI/flusser-0432452.pdf

  1. Thermopower in double planar tunnel junctions with ferromagnetic barriers and nonmagnetic electrodes

    Energy Technology Data Exchange (ETDEWEB)

    Wilczyński, M., E-mail: wilczyns@if.pw.edu.pl

    2017-01-01

    The Seebeck effect is investigated in double planar tunnel junctions consisting of nonmagnetic electrodes and the central layer separated by ferromagnetic barriers. Calculations are performed in the linear response theory using the free-electron model. The thermopower is analyzed as a function of the thickness of the central layer, temperature of the junctions and the relative orientation of magnetic moments of the barriers. It has been found that the thermopower can be significantly enhanced in the junction with special central layer thickness due to electron tunneling by resonant states. The thickness of the central layer for which the thermopower is enhanced depends not only on the temperature of the junction but also on the orientation of magnetic moments in the barriers. - Highlights: • Thermopower in the double planar junctions with magnetic barriers is analyzed. • Thermopower can be enhanced due to the resonant tunneling. • Thermopower depends on the magnetic configuration of the junction.

  2. Effect of the change in the interface structure of Pd(100)/SrTiO{sub 3} for quantum-well induced ferromagnetism

    Energy Technology Data Exchange (ETDEWEB)

    Sakuragi, Shunsuke, E-mail: sakuragi@az.appi.keio.ac.jp [Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University, Hiyoshi, Yokohama 223-0061 (Japan); Ogawa, Tomoyuki [Department of Electronic Engineering, Graduate School of Engineering, Tohoku University, Aza-Aoba, Aramaki, Aoba-ku, Sendai 980-8579 (Japan); Sato, Tetsuya [Department of Applied Physics and Physico-Informatics, Faculty of Science and Technology, Keio University, Hiyoshi, Yokohama 223-0061 (Japan)

    2017-02-01

    Measurements of temperature dependent magnetization of Pd(100) ultrathin films on SrTiO{sub 3}(100) substrates which shows quantum-well induced ferromagnetism were performed. We observed the jump in magnetization of Pd(100) due to the structural phase transition of SrTiO{sub 3}, and then, the disappearance of ferromagnetism after temperature-cycle repetition. X-ray reflectivity measurement revealed that the density of a few layers in the Pd film decreased near the Pd/SrTiO{sub 3} interface after temperature cycles. This suggests that the structural change affects the quantum-well induced ferromagnetism, and lowering of the crystallinity of Pd at the interface has a negative effect on quantum-well induced ferromagnetism of Pd(100) ultrathin films. - Highlights: • Interface manipulation of quantum-well induced ferromagnetism was performed. • Ferromagnetic Pd(100) ultrathin films on SrTiO{sub 3} substrate were prepared. • The structural phase transition of SrTiO{sub 3} degraded gradually the interface structure. • Change in the interface structure caused change in the magnetic moment of Pd. • Magnetic change was interpreted by modulation in the effective thickness of the film.

  3. The role of Co impurities and oxygen vacancies in the ferromagnetism of Co-doped SnO2: GGA and GGA+U studies

    International Nuclear Information System (INIS)

    Wang Hongxia; Yan Yu; Mohammed, Y. Sh.; Du Xiaobo; Li Kai; Jin Hanmin

    2009-01-01

    The electronic structure and ferromagnetic stability of Co-doped SnO 2 are studied using the first-principle density functional method within the generalized gradient approximation (GGA) and GGA+U schemes. The addition of effective U Co transforms the ground state of Co-doped SnO 2 to insulating from half-metallic and the coupling between the nearest neighbor Co spins to weak antimagnetic from strong ferromagnetic. GGA+U Co calculations show that the pure substitutional Co defects in SnO 2 cannot induce the ferromagnetism. Oxygen vacancies tend to locate near Co atoms. Their presence increases the magnetic moment of Co and induces the ferromagnetic coupling between two Co spins with large Co-Co distance. The calculated density of state and spin density distribution calculated by GGA+U Co show that the long-range ferromagnetic coupling between two Co spins is mediated by spin-split impurity band induced by oxygen vacancies. More charge transfer from impurity to Co-3d states and larger spin split of Co-3d and impurity states induced by the addition of U Co enhance the ferromagnetic stability of the system with oxygen vacancies. By applying a Coulomb U O on O 2 s orbital, the band gap is corrected for all calculations and the conclusions derived from GGA+U Co calculations are not changed by the correction of band gap.

  4. The electronic structure and ferromagnetism of TM (TM=V, Cr, and Mn)-doped BN(5, 5) nanotube: A first-principles study

    International Nuclear Information System (INIS)

    He, K.H.; Zheng, G.; Chen, G.; Wan, M.; Ji, G.F.

    2008-01-01

    We study the electronic structure and ferromagnetism of V-, Cr-, and Mn-doped single-wall BN(5, 5) nanotube by using polarized spin calculations within first principles. The optimized structures show that the transition-metal atoms move outwards and the calculated electronic properties demonstrate that the isolated V-, Cr-, and Mn-doped BN(5, 5) nanotubes show half-metallicity. The total ferromagnetic moments are 2μ B , 3.02μ B , and 3.98μ B for V-, Cr-, and Mn-doped BN(5, 5), respectively. The study suggests that such transition-metal (TM)-doped nanotubes may be useful in spintronics and nanomagnets

  5. Tunneling Conductance in Ferromagnetic Metal/Normal Metal/Spin-Singlet -Wave Ferromagnetic Superconductor Junctions

    Directory of Open Access Journals (Sweden)

    Hamidreza Emamipour

    2013-01-01

    Full Text Available In the framework of scattering theory, we study the tunneling conductance in a system including two junctions, ferromagnetic metal/normal metal/ferromagnetic superconductor, where ferromagnetic superconductor is in spin-singlet -wave pairing state. The non-magnetic normal metal is placed in the intermediate layer with the thickness ( which varies from 1 nm to 10000 nm. The interesting result which we have found is the existence of oscillations in conductance curves. The period of oscillations is independent of FS and FN exchange field while it depends on . The obtained results can serve as a useful tool to determine the kind of pairing symmetry in ferromagnetic superconductors.

  6. Ferromagnetism in poly(N-perfluorophenylpyrrole)

    Energy Technology Data Exchange (ETDEWEB)

    Čík, G., E-mail: gabriel.cik@stuba.sk [Department of Environmental Engineering, Faculty of Chemical and Food Technology, Slovak University of Technology, 812 37 Bratislava (Slovakia); Šeršeň, F. [Institute of Chemistry, Faculty of Natural Sciences, Comenius University, 842 15 Bratislava (Slovakia); Dlháň, L. [Department of Inorganic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, 812 37 Bratislava (Slovakia); Zálupský, P. [Department of Organic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, 812 37 Bratislava (Slovakia); Rapta, P. [Department of Physical Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, 812 37 Bratislava (Slovakia); Hrnčariková, K. [Department of Organic Chemistry, Faculty of Chemical and Food Technology, Slovak University of Technology, 812 37 Bratislava (Slovakia); Plecenik, T. [Department of Experimental Physics, Faculty of Mathematics, Physics and Informatics, Comenius University, 842 48 Bratislava (Slovakia)

    2015-10-01

    Magnetic properties of the synthesized poly(N-perfluorophenylpyrrole) were studied. The synthesized polymer dissolves in common organic solvents. By the zero-field cooling-field cooling method (ZFC–FC) we found that at low temperatures (T{sub b}<50 K) the synthetic polymer reaches a state with prevailing ferromagnetism. The synthesized polymer retained ferromagnetism even at 300 K. The anomalous magnetic behavior was explained in terms of spin–spin interaction of triplet polarons. As can be seen from the calculated spin density of SOMO and SOMO 1 such a state arise as a consequence of 1-D spin interactions of polarons. Based on the calculated and visualized spin density (SOMO) on the polymer chain such interactions can be explained by the theory of flat-band-ferromagnetism. - Highlights: • We synthesized a new conducting polymer poly(N-perfluorophenylpyrrole). • By the ZFC–FC and EPR methods we measured magnetic properties of the prepared polymer. • We discussed stability and interactions of the polarons in triplet states. • At low temperatures the synthesized polymer reached ferromagnetism.

  7. On piezomagnetism at viscoplasticity of ferromagnetics

    International Nuclear Information System (INIS)

    Micunovic, M.

    2001-01-01

    The paper deals with viscoplasticity of ferromagnetic materials. Tensor representation is applied to a set of evolution equations comprising the plastic stretching and residual magnetization tensors. Small magnetoelastic strains of isotropic insulators are considered in detail in two special cases of finite as well as small plastic strain. A special emphasis is given to piezomagnetism effects in the case of uniaxial cycling strain (author)

  8. Magnetic profiles in ferromagnetic/superconducting superlattices.

    Energy Technology Data Exchange (ETDEWEB)

    te Velthuis, S. G. E.; Hoffmann, A.; Santamaria, J.; Materials Science Division; Univ. Complutense de Madrid

    2007-02-28

    The interplay between ferromagnetism and superconductivity has been of longstanding fundamental research interest to scientists, as the competition between these generally mutually exclusive types of long-range order gives rise to a rich variety of physical phenomena. A method of studying these exciting effects is by investigating artificially layered systems, i.e. alternating deposition of superconducting and ferromagnetic thin films on a substrate, which enables a straight-forward combination of the two types of long-range order and allows the study of how they compete at the interface over nanometer length scales. While originally studies focused on low temperature superconductors interchanged with metallic ferromagnets, in recent years the scope has broadened to include superlattices of high T{sub c} superconductors and colossal magnetoresistance oxides. Creating films where both the superconducting as well as the ferromagnetic layers are complex oxide materials with similar crystal structures (Figure 1), allows the creation of epitaxial superlattices, with potentially atomically flat and ordered interfaces.

  9. Angular and linear momentum of excited ferromagnets

    NARCIS (Netherlands)

    Yan, P.; Kamra, A.; Cao, Y.; Bauer, G.E.W.

    2013-01-01

    The angular momentum vector of a Heisenberg ferromagnet with isotropic exchange interaction is conserved, while under uniaxial crystalline anisotropy the projection of the total spin along the easy axis is a constant of motion. Using Noether's theorem, we prove that these conservation laws persist

  10. Ferromagnetic hysteresis and the effective field

    NARCIS (Netherlands)

    Naus, H.W.L.

    2002-01-01

    The Jiles-Atherton model of the behavior of ferromagnetic materials determines the irreversible magnetization from the effective field by using a differential equation. This paper presents an exact, analytical solution to the equation, one displaying hysteresis. The inclusion of magnetomechanical

  11. Ferromagnetism in diluted magnetic semiconductor heterojunction systems

    Czech Academy of Sciences Publication Activity Database

    Lee, B.; Jungwirth, Tomáš; MacDonald, A. H.

    2002-01-01

    Roč. 17, - (2002), s. 393-403 ISSN 0268-1242 R&D Projects: GA ČR GA202/98/0085; GA MŠk OC P5.10 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferromagnetic semiconductors * heterostructures Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.241, year: 2002

  12. Pseudospin anisotropy classification of quantum Hall ferromagnets

    Czech Academy of Sciences Publication Activity Database

    Jungwirth, Tomáš; MacDonald, A. H.

    2000-01-01

    Roč. 63, č. 3 (2000), s. 035305-1 - 035305-9 ISSN 0163-1829 R&D Projects: GA ČR GA202/98/0085 Institutional research plan: CEZ:AV0Z1010914 Keywords : quantum Hall ferromagnets * anisotropy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.065, year: 2000

  13. Skyrmion physics in Bose-Einstein ferromagnets

    NARCIS (Netherlands)

    Al Khawaja, U.; Stoof, H.T.C.

    2001-01-01

    We show that a ferromagnetic Bose-Einstein condensate has not only line-like vortex excitations, but in general, also allows for pointlike topological excitations, i.e., skyrmions. We discuss the thermodynamic stability and the dynamic properties of these skyrmions for both spin-1/2 and

  14. Nonmonotonic critical temperature in superconductor ferromagnet bilayers

    NARCIS (Netherlands)

    Fominov, Ya. V.; Fominov, I.V.; Chtchelkatchev, N.M.; Golubov, Alexandre Avraamovitch

    2002-01-01

    The critical temperature Tc of a superconductor/ferromagnet (SF) bilayer can exhibit nonmonotonic dependence on the thickness df of the F layer. SF systems have been studied for a long time; according to the experimental situation, a ¿dirty¿ limit is often considered which implies that the mean free

  15. Magnetization dissipation in ferromagnets from scattering theory

    NARCIS (Netherlands)

    Brataas, A.; Tserkovnyak, Y.; Bauer, G.E.W.

    2011-01-01

    The magnetization dynamics of ferromagnets is often formulated in terms of the Landau-Lifshitz-Gilbert (LLG) equation. The reactive part of this equation describes the response of the magnetization in terms of effective fields, whereas the dissipative part is parametrized by the Gilbert damping

  16. Room-temperature ferromagnetic and photoluminescence ...

    Indian Academy of Sciences (India)

    the ferromagnetic nature of ITO and the strength of magnetization is superior to those of In2O3 and SnO2. However, ... ties in the spintronic devices, the materials suitable for such devices ... into suitable quartz test tubes (10mm) whose interior was enclosed in .... related to metal indium In0 with binding energy 443.6 eV was.

  17. Neutron Depolarization in Submicron Ferromagnetic Materials

    NARCIS (Netherlands)

    Rekveldt, M.Th.

    1989-01-01

    The neutron depolarization technique is based on the loss of polarization of a polarized neutron beam after transmission through ferromagnetic substances. This loss, caused by Larmor precession in individual domains, determines the mean domain size, the mean square direction cosines of the domains

  18. Lattice effects on ferromagnetism in perovskite ruthenates

    Science.gov (United States)

    Cheng, J.-G.; Zhou, J.-S.; Goodenough, John B.

    2013-01-01

    Ferromagnetism and its evolution in the orthorhombic perovskite system Sr1–xCaxRuO3 have been widely believed to correlate with structural distortion. The recent development of high-pressure synthesis of the Ba-substituted Sr1–yBayRuO3 makes it possible to study ferromagnetism over a broader phase diagram, which includes the orthorhombic Imma and the cubic phases. However, the chemical substitutions introduce the A-site disorder effect on Tc, which complicates determination of the relationship between ferromagnetism and structural distortion. By clarifying the site disorder effect on Tc in several unique series of ruthenates in which the average bond length 〈A–O〉 remains the same but the bond-length variance varies, we are able to demonstrate a parabolic curve of Tc versus mean bond length 〈A–O〉. A much higher Tc ∼ 177 K than that found in orthorhombic SrRuO3 can be obtained from the curve at a bond length 〈A–O〉, which makes the geometric factor t = 〈A–O〉/(√2〈Ru–O〉) ∼ 1. This result reveals not only that the ferromagnetism in the ruthenates is extremely sensitive to the lattice strain, but also that it has an important implication for exploring the structure–property relationship in a broad range of oxides with perovskite or a perovskite-related structure. PMID:23904477

  19. Electric Field Controlled Magnetism in BiFeO3/Ferromagnet Films

    Science.gov (United States)

    Holcomb, M. B.; Chu, Y. H.; Martin, L. W.; Gajek, M.; Seidel, J.; Ramesh, R.; Scholl, A.; Fraile-Rodriguez, A.

    2008-03-01

    Electric field control of magnetism is a hot technological topic at the moment due to its potential to revolutionize today's devices. Magnetoelectric materials, those having both electric and magnetic order and the potential for coupling between the two, are a promising avenue to approach electric control. BiFeO3, both a ferroelectric and an antiferromagnet, is the only single phase room temperature magnetoelectric that is currently known. In addition to other possibilities, its multiferroic nature has potential in the very active field of exchange bias, where an antiferromagnetic thin film pins the magnetic direction of an adjoining ferromagnetic layer. Since this antiferromagnet is electrically tunable, this coupling could allow electric-field control of the ferromagnetic magnetization. Direction determination of antiferromagnetic domains in BFO has recently been shown using linear and circular dichroism studies. Recently, this technique has been extended to look at the magnetic domains of a ferromagnetic grown on top of BFO. The clear magnetic changes induced by application of electric fields reveal the possibility of electric control.

  20. Net Zero Energy Buildings

    DEFF Research Database (Denmark)

    Marszal, Anna Joanna; Bourrelle, Julien S.; Gustavsen, Arild

    2010-01-01

    and identify possible renewable energy supply options which may be considered in calculations. Finally, the gap between the methodology proposed by each organisation and their respective national building code is assessed; providing an overview of the possible changes building codes will need to undergo......The international cooperation project IEA SHC Task 40 / ECBCS Annex 52 “Towards Net Zero Energy Solar Buildings”, attempts to develop a common understanding and to set up the basis for an international definition framework of Net Zero Energy Buildings (Net ZEBs). The understanding of such buildings...

  1. Getting to Net Zero

    Energy Technology Data Exchange (ETDEWEB)

    2016-09-01

    The technology necessary to build net zero energy buildings (NZEBs) is ready and available today, however, building to net zero energy performance levels can be challenging. Energy efficiency measures, onsite energy generation resources, load matching and grid interaction, climatic factors, and local policies vary from location to location and require unique methods of constructing NZEBs. It is recommended that Components start looking into how to construct and operate NZEBs now as there is a learning curve to net zero construction and FY 2020 is just around the corner.

  2. Pro NET Best Practices

    CERN Document Server

    Ritchie, Stephen D

    2011-01-01

    Pro .NET Best Practices is a practical reference to the best practices that you can apply to your .NET projects today. You will learn standards, techniques, and conventions that are sharply focused, realistic and helpful for achieving results, steering clear of unproven, idealistic, and impractical recommendations. Pro .NET Best Practices covers a broad range of practices and principles that development experts agree are the right ways to develop software, which includes continuous integration, automated testing, automated deployment, and code analysis. Whether the solution is from a free and

  3. Magnetic damping phenomena in ferromagnetic thin-films and multilayers

    Science.gov (United States)

    Azzawi, S.; Hindmarch, A. T.; Atkinson, D.

    2017-11-01

    Damped ferromagnetic precession is an important mechanism underpinning the magnetisation processes in ferromagnetic materials. In thin-film ferromagnets and ferromagnetic/non-magnetic multilayers, the role of precession and damping can be critical for spintronic device functionality and as a consequence there has been significant research activity. This paper presents a review of damping in ferromagnetic thin-films and multilayers and collates the results of many experimental studies to present a coherent synthesis of the field. The terms that are used to define damping are discussed with the aim of providing consistent definitions for damping phenomena. A description of the theoretical basis of damping is presented from early developments to the latest discussions of damping in ferromagnetic thin-films and multilayers. An overview of the time and frequency domain methods used to study precessional magnetisation behaviour and damping in thin-films and multilayers is also presented. Finally, a review of the experimental observations of magnetic damping in ferromagnetic thin-films and multilayers is presented with the most recent explanations. This brings together the results from many studies and includes the effects of ferromagnetic film thickness, the effects of composition on damping in thin-film ferromagnetic alloys, the influence of non-magnetic dopants in ferromagnetic films and the effects of combining thin-film ferromagnets with various non-magnetic layers in multilayered configurations.

  4. Scanning X-ray microscopy of superconductor/ferromagnet bilayers

    Energy Technology Data Exchange (ETDEWEB)

    Stahl, Claudia; Ruoss, Stephen; Weigand, Markus; Schuetz, Gisela [Max Planck Institute for Intelligent Systems, Stuttgart (Germany); Zahn, Patrick; Bayer, Jonas [Max Planck Institute for Intelligent Systems, Stuttgart (Germany); Research Institute for Innovative Surfaces, FINO, Aalen University (Germany); Albrecht, Joachim [Research Institute for Innovative Surfaces, FINO, Aalen University (Germany)

    2016-07-01

    The magnetic flux distribution arising from a high-T{sub c} superconductor is detected and visualized with high spatial resolution using scanning x-ray microscopy (SXM). Therefore, we introduce a sensor layer, namely, an amorphous, soft-magnetic CoFeB cover layer. The magnetic stray fields of the supercurrents lead to a local reorientation of the magnetic moments in the ferromagnet, which is visualized using the large x-ray magnetic circular dichroism (XMCD) effect of the Co and Fe L3-edge. We show that the XMCD contrast in the sensor layer corresponds to the in-plane magnetic flux distribution of the superconductor and can hence be used to image magnetic structures in superconductors with high spatial resolution. Using the total electron yield (TEY) mode the surface structure and the magnetic domains can be imaged simultaneously and can be correlated. The measurements are carried out at our scanning x-ray microscope MAXYMUS at Bessy II, Berlin with the new low temperature setup.

  5. Electric moments in molecule interferometry

    International Nuclear Information System (INIS)

    Eibenberger, Sandra; Gerlich, Stefan; Arndt, Markus; Tuexen, Jens; Mayor, Marcel

    2011-01-01

    We investigate the influence of different electric moments on the shift and dephasing of molecules in a matter wave interferometer. Firstly, we provide a quantitative comparison of two molecules that are non-polar yet polarizable in their thermal ground state and that differ in their stiffness and response to thermal excitations. While C 25 H 20 is rather rigid, its larger derivative C 49 H 16 F 52 is additionally equipped with floppy side chains and vibrationally activated dipole moment variations. Secondly, we elucidate the role of a permanent electric dipole momentby contrasting the quantum interference pattern of a (nearly) non-polar and a polar porphyrin derivative. We find that a high molecular polarizability and even sizeable dipole moment fluctuations are still well compatible with high-contrast quantum interference fringes. The presence of permanent electric dipole moments, however, can lead to a dephasing and rapid degradation of the quantum fringe pattern already at moderate electric fields. This finding is of high relevance for coherence experiments with large organic molecules, which are generally equipped with strong electric moments.

  6. Fingerprints of entangled spin and orbital physics in itinerant ferromagnets via angle-resolved resonant photoemission

    Science.gov (United States)

    Da Pieve, F.

    2016-01-01

    A method for mapping the local spin and orbital nature of the ground state of a system via corresponding flip excitations is proposed based on angle-resolved resonant photoemission and related diffraction patterns, obtained here via an ab initio modified one-step theory of photoemission. The analysis is done on the paradigmatic weak itinerant ferromagnet bcc Fe, whose magnetism, a correlation phenomenon given by the coexistence of localized moments and itinerant electrons, and the observed non-Fermi-Liquid behavior at extreme conditions both remain unclear. The combined analysis of energy spectra and diffraction patterns offers a mapping of local pure spin-flip, entangled spin-flip-orbital-flip excitations and chiral transitions with vortexlike wave fronts of photoelectrons, depending on the valence orbital symmetry and the direction of the local magnetic moment. Such effects, mediated by the hole polarization, make resonant photoemission a promising tool to perform a full tomography of the local magnetic properties even in itinerant ferromagnets or macroscopically nonmagnetic systems.

  7. Induced magnetization spiral in a nonmagnetic metal sandwiched between two ferromagnets

    CERN Document Server

    Mathon, J; Villeret, M; Muniz, R B; Edwards, D M

    2000-01-01

    Calculation of the magnetic moment induced in a non-magnetic metal, sandwiched between two ferromagnets with magnetizations at an arbitrary angle, is reported. It is found that the induced magnetization rotates along a complex three-dimensional spiral and can undergo many complete 360 deg. rotations. A simple free-electron model is used to derive an analytic formula for the twist angle phi inside the spacer. This demonstrates that, contrary to the behavior of magnetization inside a domain wall in a ferromagnet, phi varies non-uniformly inside the spacer and exhibits plateaus of almost constant rotation separated by regions of sharp rotations by large angles. The calculation is extended to the case of a realistic Co/Cu/Co(0 0 1) trilayer described by s, p, d tight-binding bands fitted to an ab initio band structure. An analytic formula for the components of the induced moment (and hence, for phi) is derived using the stationary phase approximation. Its validity is tested against a fully numerical calculation u...

  8. Methods for Computing Accurate Atomic Spin Moments for Collinear and Noncollinear Magnetism in Periodic and Nonperiodic Materials.

    Science.gov (United States)

    Manz, Thomas A; Sholl, David S

    2011-12-13

    The partitioning of electron spin density among atoms in a material gives atomic spin moments (ASMs), which are important for understanding magnetic properties. We compare ASMs computed using different population analysis methods and introduce a method for computing density derived electrostatic and chemical (DDEC) ASMs. Bader and DDEC ASMs can be computed for periodic and nonperiodic materials with either collinear or noncollinear magnetism, while natural population analysis (NPA) ASMs can be computed for nonperiodic materials with collinear magnetism. Our results show Bader, DDEC, and (where applicable) NPA methods give similar ASMs, but different net atomic charges. Because they are optimized to reproduce both the magnetic field and the chemical states of atoms in a material, DDEC ASMs are especially suitable for constructing interaction potentials for atomistic simulations. We describe the computation of accurate ASMs for (a) a variety of systems using collinear and noncollinear spin DFT, (b) highly correlated materials (e.g., magnetite) using DFT+U, and (c) various spin states of ozone using coupled cluster expansions. The computed ASMs are in good agreement with available experimental results for a variety of periodic and nonperiodic materials. Examples considered include the antiferromagnetic metal organic framework Cu3(BTC)2, several ozone spin states, mono- and binuclear transition metal complexes, ferri- and ferro-magnetic solids (e.g., Fe3O4, Fe3Si), and simple molecular systems. We briefly discuss the theory of exchange-correlation functionals for studying noncollinear magnetism. A method for finding the ground state of systems with highly noncollinear magnetism is introduced. We use these methods to study the spin-orbit coupling potential energy surface of the single molecule magnet Fe4C40H52N4O12, which has highly noncollinear magnetism, and find that it contains unusual features that give a new interpretation to experimental data.

  9. PhysioNet

    Data.gov (United States)

    U.S. Department of Health & Human Services — The PhysioNet Resource is intended to stimulate current research and new investigations in the study of complex biomedical and physiologic signals. It offers free...

  10. NetSig

    DEFF Research Database (Denmark)

    Horn, Heiko; Lawrence, Michael S; Chouinard, Candace R

    2018-01-01

    Methods that integrate molecular network information and tumor genome data could complement gene-based statistical tests to identify likely new cancer genes; but such approaches are challenging to validate at scale, and their predictive value remains unclear. We developed a robust statistic (Net......Sig) that integrates protein interaction networks with data from 4,742 tumor exomes. NetSig can accurately classify known driver genes in 60% of tested tumor types and predicts 62 new driver candidates. Using a quantitative experimental framework to determine in vivo tumorigenic potential in mice, we found that Net......Sig candidates induce tumors at rates that are comparable to those of known oncogenes and are ten-fold higher than those of random genes. By reanalyzing nine tumor-inducing NetSig candidates in 242 patients with oncogene-negative lung adenocarcinomas, we find that two (AKT2 and TFDP2) are significantly amplified...

  11. Blanket testing in NET

    International Nuclear Information System (INIS)

    Chazalon, M.; Daenner, W.; Libin, B.

    1989-01-01

    The testing stages in NET for the performance assessment of the various breeding blanket concepts developed at the present time in Europe for DEMO (LiPb and ceramic blankets) and the requirements upon NET to perform these tests are reviewed. Typical locations available in NET for blanket testing are the central outboard segments and the horizontal ports of in-vessel sectors. These test positions will be connectable with external test loops. The number of test loops (helium, water, liquid metal) will be such that each major class of blankets can be tested in NET. The test positions, the boundary conditions and the external test loops are identified and the requirements for test blankets are summarized (author). 6

  12. Programming NET 35

    CERN Document Server

    Liberty, Jesse

    2009-01-01

    Bestselling author Jesse Liberty and industry expert Alex Horovitz uncover the common threads that unite the .NET 3.5 technologies, so you can benefit from the best practices and architectural patterns baked into the new Microsoft frameworks. The book offers a Grand Tour" of .NET 3.5 that describes how the principal technologies can be used together, with Ajax, to build modern n-tier and service-oriented applications. "

  13. NET SALARY ADJUSTMENT

    CERN Multimedia

    Finance Division

    2001-01-01

    On 15 June 2001 the Council approved the correction of the discrepancy identified in the net salary adjustment implemented on 1st January 2001 by retroactively increasing the scale of basic salaries to achieve the 2.8% average net salary adjustment approved in December 2000. We should like to inform you that the corresponding adjustment will be made to your July salary. Full details of the retroactive adjustments will consequently be shown on your pay slip.

  14. Instability of the ferromagnetic ground state in Lu.sub.2./sub.Fe.sub.17-x./sub.Mn.sub.x./sub. [x = 0.5, 0.7

    Czech Academy of Sciences Publication Activity Database

    Arnold, Zdeněk; Kuchin, A.; Kamarád, Jiří

    2012-01-01

    Roč. 111, č. 7 (2012), "07E310-1"-"07E310-3" ISSN 0021-8979 R&D Projects: GA ČR GA202/09/1027 Institutional research plan: CEZ:AV0Z10100521 Keywords : ferromagnetic ground state, Magnetic moments * magnetic moments Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.210, year: 2012

  15. The half-metallic ferromagnetism character in Be{sub 1−x}V{sub x}Y (Y=Se and Te) alloys: An ab-initio study

    Energy Technology Data Exchange (ETDEWEB)

    Sajjad, M. [School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Manzoor, Sadia [Department of Physics, University of the Punjab, Quaid-e-Azam Campus, 54590 Lahore (Pakistan); Zhang, H.X. [School of Electronic Engineering, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Beijing Key Laboratory of Work Safety Intelligent Monitoring, Beijing University of Posts and Telecommunications, Beijing 100876 (China); Noor, N.A. [Department of Physics, University of the Punjab, Quaid-e-Azam Campus, 54590 Lahore (Pakistan); Alay-e-Abbas, S.M. [Department of Physics, GC University Faisalabad, Allama Iqbal Road, Faisalabad 38000 (Pakistan); Department of Physics, University of Sargodha, Sargodha 40100 (Pakistan); Shaukat, A. [Department of Physics, University of Sargodha, Sargodha 40100 (Pakistan); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique et de Modélisation Mathématique (LPQ3M), Département de Technologie, Université de Mascara, Mascara 29000 (Algeria)

    2015-04-01

    Ab-initio calculations for V-doped BeSe and BeTe semiconductors are performed by means of all-electrons full-potential linearized augmented plane wave plus local orbital (FP-LAPW+lo) method. The structural properties are optimized using the Wu-Cohen generalized gradient approximation functional, whereas modified Becke and Jhonson local density approximation functional has been employed for evaluating the spin-polarized electronic and magnetic properties. Magnetic stability at various doping concentrations in ferromagnetic (FM) and anti-ferromagnetic (AFM) ordering is investigated by comparing the minimum total energies and enthalpies of formation (ΔH). Studied band structures, density of states, total energy, exchange interactions and magnetic moments manifest both alloys with half-metallic ferromagnetic behavior. Moreover, their valance bands are found to be paired ferromagnetically with V atoms. Furthermore, it was observed that the magnetic moment of vanadium atom reduces from free space charge value due to p–d hybridization which yields small magnetic moments on the Be, Se and Te sites. - Highlights: • Density functional calculations for V-doped BeSe and BeTe are performed. • V-doped BeSe and BeTe are found to be stable half-metallic ferromagnetism. • Improved electronic properties are achieved using mBJLDA which confirm HMF. • The half-metallic gaps show non-linear variation with increasing dopant concentration.

  16. Stochastic Generalized Method of Moments

    KAUST Repository

    Yin, Guosheng; Ma, Yanyuan; Liang, Faming; Yuan, Ying

    2011-01-01

    The generalized method of moments (GMM) is a very popular estimation and inference procedure based on moment conditions. When likelihood-based methods are difficult to implement, one can often derive various moment conditions and construct the GMM objective function. However, minimization of the objective function in the GMM may be challenging, especially over a large parameter space. Due to the special structure of the GMM, we propose a new sampling-based algorithm, the stochastic GMM sampler, which replaces the multivariate minimization problem by a series of conditional sampling procedures. We develop the theoretical properties of the proposed iterative Monte Carlo method, and demonstrate its superior performance over other GMM estimation procedures in simulation studies. As an illustration, we apply the stochastic GMM sampler to a Medfly life longevity study. Supplemental materials for the article are available online. © 2011 American Statistical Association.

  17. Stochastic Generalized Method of Moments

    KAUST Repository

    Yin, Guosheng

    2011-08-16

    The generalized method of moments (GMM) is a very popular estimation and inference procedure based on moment conditions. When likelihood-based methods are difficult to implement, one can often derive various moment conditions and construct the GMM objective function. However, minimization of the objective function in the GMM may be challenging, especially over a large parameter space. Due to the special structure of the GMM, we propose a new sampling-based algorithm, the stochastic GMM sampler, which replaces the multivariate minimization problem by a series of conditional sampling procedures. We develop the theoretical properties of the proposed iterative Monte Carlo method, and demonstrate its superior performance over other GMM estimation procedures in simulation studies. As an illustration, we apply the stochastic GMM sampler to a Medfly life longevity study. Supplemental materials for the article are available online. © 2011 American Statistical Association.

  18. Room temperature p-type conductivity and coexistence of ferroelectric order in ferromagnetic Li doped ZnO nanoparticles

    KAUST Repository

    Awan, Saif Ullah

    2014-10-28

    Memory and switching devices acquired new materials which exhibit ferroelectric and ferromagnetic order simultaneously. We reported multiferroic behavior in Zn1-yLiyO(0.00≤y≤0.10) nanoparticles. The analysis of transmission electron micrographs confirmed the hexagonal morphology and wurtzite crystalline structure. We investigated p-type conductivity in doped samples and measured hole carriers in range 2.4×1017/cc to 7.3×1017/cc for different Li contents. We found that hole carriers are responsible for long range order ferromagnetic coupling in Li doped samples. Room temperature ferroelectric hysteresis loops were observed in 8% and 10% Li doped samples. We demonstrated ferroelectric coercivity (remnant polarization) 2.5kV/cm (0.11 μC/cm2) and 2.8kV/cm (0.15 μC/cm2) for y=0.08 and y=0.10 samples. We propose that the mechanism of Li induced ferroelectricity in ZnO is due to indirect dipole interaction via hole carriers. We investigated that if the sample has hole carriers ≥5.3×1017/cc, they can mediate the ferroelectricity. Ferroelectric and ferromagnetic measurements showed that higher electric polarization and larger magnetic moment is attained when the hole concentration is larger and vice versa. Our results confirmed the hole dependent coexistence of ferromagnetic and ferroelectric behavior at room temperature, which provide potential applications for switchable and memory devices.

  19. Gate-Tunable Spin Exchange Interactions and Inversion of Magnetoresistance in Single Ferromagnetic ZnO Nanowires.

    Science.gov (United States)

    Modepalli, Vijayakumar; Jin, Mi-Jin; Park, Jungmin; Jo, Junhyeon; Kim, Ji-Hyun; Baik, Jeong Min; Seo, Changwon; Kim, Jeongyong; Yoo, Jung-Woo

    2016-04-26

    Electrical control of ferromagnetism in semiconductor nanostructures offers the promise of nonvolatile functionality in future semiconductor spintronics. Here, we demonstrate a dramatic gate-induced change of ferromagnetism in ZnO nanowire (NW) field-effect transistors (FETs). Ferromagnetism in our ZnO NWs arose from oxygen vacancies, which constitute deep levels hosting unpaired electron spins. The magnetic transition temperature of the studied ZnO NWs was estimated to be well above room temperature. The in situ UV confocal photoluminescence (PL) study confirmed oxygen vacancy mediated ferromagnetism in the studied ZnO NW FET devices. Both the estimated carrier concentration and temperature-dependent conductivity reveal the studied ZnO NWs are at the crossover of the metal-insulator transition. In particular, gate-induced modulation of the carrier concentration in the ZnO NW FET significantly alters carrier-mediated exchange interactions, which causes even inversion of magnetoresistance (MR) from negative to positive values. Upon sweeping the gate bias from -40 to +50 V, the MRs estimated at 2 K and 2 T were changed from -11.3% to +4.1%. Detailed analysis on the gate-dependent MR behavior clearly showed enhanced spin splitting energy with increasing carrier concentration. Gate-voltage-dependent PL spectra of an individual NW device confirmed the localization of oxygen vacancy-induced spins, indicating that gate-tunable indirect exchange coupling between localized magnetic moments played an important role in the remarkable change of the MR.

  20. Method of moments in electromagnetics

    CERN Document Server

    Gibson, Walton C

    2007-01-01

    Responding to the need for a clear, up-to-date introduction to the field, The Method of Moments in Electromagnetics explores surface integral equations in electromagnetics and presents their numerical solution using the method of moments (MOM) technique. It provides the numerical implementation aspects at a nuts-and-bolts level while discussing integral equations and electromagnetic theory at a higher level. The author covers a range of topics in this area, from the initial underpinnings of the MOM to its current applications. He first reviews the frequency-domain electromagnetic theory and t

  1. Neutron star moments of inertia

    Science.gov (United States)

    Ravenhall, D. G.; Pethick, C. J.

    1994-01-01

    An approximation for the moment of inertia of a neutron star in terms of only its mass and radius is presented, and insight into it is obtained by examining the behavior of the relativistic structural equations. The approximation is accurate to approximately 10% for a variety of nuclear equations of state, for all except very low mass stars. It is combined with information about the neutron-star crust to obtain a simple expression (again in terms only of mass and radius) for the fractional moment of inertia of the crust.

  2. Manipulation of incoherent and coherent spin ensembles in diluted magnetic semiconductors via ferromagnetic fringe fields; Manipulation inkohaerenter und kohaerenter Spinensembles in verduennt-magnetischen Halbleitern mittels ferromagnetischer Streufelder

    Energy Technology Data Exchange (ETDEWEB)

    Halm, Simon

    2009-05-19

    In this thesis it is demonstrated that fringe fields of nanostructured ferromagnets provide the opportunity to manipulate both incoherent and coherent spin ensembles in a dilute magnetic semiconductor (DMS). Fringe fields of Fe/Tb ferromagnets with a remanent out-of-plane magnetization induce a local magnetization in a (Zn,Cd,Mn)Se DMS. Due to the sp-d exchange interaction, optically generated electron-hole pairs align their spin along the DMS magnetization. One obtains a local, remanent spin polarization which was probed by spatially resolved, polarization sensitive photoluminescence spectroscopy. Fringe fields from in-plane magnetized Co ferromagnets allow to locally modify the precession frequency of the Manganese magnetic moments of the DMS in an external magnetic field. This was probed by time-resolved Kerr rotation technique. The inhomogeneity of the fringe field leads to a shortening of the ensemble decoherence time and to the effect of a time-dependent ensemble precession frequency. (orig.)

  3. Magnetic Circular X-ray Dichroism Study of Paramagnetic and Anti-Ferromagnetic States in SrFeO3 Using a 10-T Superconducting Magnet

    International Nuclear Information System (INIS)

    Okamoto, J.; Mamiya, K.; Fujimori, S.-I.; Okane, T.; Saitoh, Y.; Muramatsu, Y.; Fujimori, A.; Ishiwata, S.; Takano, M.

    2004-01-01

    Magnetic circular x-ray dichroism (MCXD) measurements in Fe 2p absorption have been done on SrFeO3, which shows a spiral anti-ferromagnetism, by using a 10-T superconducting magnet. Finite MCXD structures have been observed under magnetic field of 8 T even in the paramagnetic and anti-ferromagnetic states. The intensity of the MCXD structure at hv ∼ 710 eV increases linearly as magnetic field increases linearly and the total magnetic moments estimated by MCXD sum rules roughly corresponds to the magnetization measured by SQUID measurements. MCXD study of paramagnetic and/or anti-ferromagnetic samples can be done by using a superconducting magnet that generates a strong magnetic field enough to induce finite magnetization

  4. Explanations pertaining to the Hip Joint Flexor Moment During the Stance Phase of Human Walking

    DEFF Research Database (Denmark)

    Simonsen, Erik B; Cappelen, Katrine L; Skorini, Ragnhild

    2012-01-01

    A hip joint flexor moment in the last half of the stance phase during walking has repeatedly been reported. However, the purpose of this moment remains uncertain and it is unknown how it is generated. Nine male subjects were instructed to walk at 4.5 km/h with their upper body in three different...... positions: normal, inclined and reclined. Net joint moments were calculated about the hip, knee and ankle joint. The peak hip joint flexor moment during late stance was significantly lower during inclined walking than in the two other conditions. During normal walking the iliacus muscle showed no or very...... weak activity and first at the transition from stance to swing. When walking reclined, a clear but rather low activity level of the iliacus muscle was seen in the first half of the stance phase, which could contribute to the hip moment. In the inclined condition the iliacus showed much increased...

  5. Topological Aspects of Solitons in Ferromagnets

    International Nuclear Information System (INIS)

    Ren Jirong; Wang Jibiao; Li Ran; Xu Donghui; Duan Yishi

    2008-01-01

    Two kinds of topological soliton (skyrmion and magnetic vortex ring) in ferromagnets are studied. They have the common topological origin, a tensor H αβ = n-vector · (∂ α n-vector x ∂ β n-vector ), which describes the non-trivial distribution of local orientation of magnetization n-vector at large distances in space. The topological stability of skyrmion is protected by the winding number. Knot-like topological defect as magnetic vortex rings is also studied. On the assumption that magnetic vortex rings are geometric lines, we present their δ-function distribution in ferromagnetic materials. Furthermore, it is briefly shown that Hopf invariant is a proper topological invariant to describe the topology of magnetic vortex rings

  6. Ferromagnetism of Magnesium Oxide

    Directory of Open Access Journals (Sweden)

    Jitendra Pal Singh

    2017-11-01

    Full Text Available Magnetism without d-orbital electrons seems to be unrealistic; however, recent observations of magnetism in non-magnetic oxides, such as ZnO, HfO2, and MgO, have opened new avenues in the field of magnetism. Magnetism exhibited by these oxides is known as d° ferromagnetism, as these oxides either have completely filled or unfilled d-/f-orbitals. This magnetism is believed to occur due to polarization induced by p-orbitals. Magnetic polarization in these oxides arises due to vacancies, the excitation of trapped spin in the triplet state. The presence of vacancies at the surface and subsurface also affects the magnetic behavior of these oxides. In the present review, origins of magnetism in magnesium oxide are discussed to obtain understanding of d° ferromagnetism.

  7. Ising ferromagnet: zero-temperature dynamic evolution

    International Nuclear Information System (INIS)

    Oliveira, P M C de; Newman, C M; Sidoravicious, V; Stein, D L

    2006-01-01

    The dynamic evolution at zero temperature of a uniform Ising ferromagnet on a square lattice is followed by Monte Carlo computer simulations. The system always eventually reaches a final, absorbing state, which sometimes coincides with a ground state (all spins parallel), and sometimes does not (parallel stripes of spins up and down). We initiate here the numerical study of 'chaotic time dependence' (CTD) by seeing how much information about the final state is predictable from the randomly generated quenched initial state. CTD was originally proposed to explain how nonequilibrium spin glasses could manifest an equilibrium pure state structure, but in simpler systems such as homogeneous ferromagnets it is closely related to long-term predictability and our results suggest that CTD might indeed occur in the infinite volume limit

  8. Silicon spintronics with ferromagnetic tunnel devices

    International Nuclear Information System (INIS)

    Jansen, R; Sharma, S; Dash, S P; Min, B C

    2012-01-01

    In silicon spintronics, the unique qualities of ferromagnetic materials are combined with those of silicon, aiming at creating an alternative, energy-efficient information technology in which digital data are represented by the orientation of the electron spin. Here we review the cornerstones of silicon spintronics, namely the creation, detection and manipulation of spin polarization in silicon. Ferromagnetic tunnel contacts are the key elements and provide a robust and viable approach to induce and probe spins in silicon, at room temperature. We describe the basic physics of spin tunneling into silicon, the spin-transport devices, the materials aspects and engineering of the magnetic tunnel contacts, and discuss important quantities such as the magnitude of the spin accumulation and the spin lifetime in the silicon. We highlight key experimental achievements and recent progress in the development of a spin-based information technology. (topical review)

  9. On the critical frontiers of Potts ferromagnets

    International Nuclear Information System (INIS)

    Magalhaes, A.C.N. de; Tsallis, C.

    1981-01-01

    A conjecture concerning the critical frontiers of q- state Potts ferromagnets on d- dimensional lattices (d > 1) which generalize a recent one stated for planar lattices is formulated. The present conjecture is verified within satisfactory accuracy (exactly in some cases) for all the lattices or arrays whose critical points are known. Its use leads to the prediction of: a) a considerable amount of new approximate critical points (26 on non-planar regular lattices, some others on Husimi trees and cacti); b) approximate critical frontiers for some 3- dimensional lattices; c) the possibly asymptotically exact critical point on regular lattices in the limit d→infinite for all q>=1; d) the possibly exact critical frontier for the pure Potts model on fully anisotropic Bethe lattices; e) the possibly exact critical frontier for the general quenched random-bond Potts ferromagnet (any P(J)) on isotropic Bethe lattices. (Author) [pt

  10. Itinerant ferromagnetism in the As 4p conduction band of Ba_{0.6}K_{0.4}Mn_{2}As_{2} identified by X-ray magnetic circular dichroism.

    Science.gov (United States)

    Ueland, B G; Pandey, Abhishek; Lee, Y; Sapkota, A; Choi, Y; Haskel, D; Rosenberg, R A; Lang, J C; Harmon, B N; Johnston, D C; Kreyssig, A; Goldman, A I

    2015-05-29

    X-ray magnetic circular dichroism (XMCD) measurements on single-crystal and powder samples of Ba_{0.6}K_{0.4}Mn_{2}As_{2} show that the ferromagnetism below T_{C}≈100  K arises in the As 4p conduction band. No XMCD signal is observed at the Mn x-ray absorption edges. Below T_{C}, however, a clear XMCD signal is found at the As K edge which increases with decreasing temperature. The XMCD signal is absent in data taken with the beam directed parallel to the crystallographic c axis indicating that the orbital magnetic moment lies in the basal plane of the tetragonal lattice. These results show that the previously reported itinerant ferromagnetism is associated with the As 4p conduction band and that distinct local-moment antiferromagnetism and itinerant ferromagnetism with perpendicular easy axes coexist in this compound at low temperature.

  11. Magnetic moments, coupling, and interface interdiffusion in Fe/V(001) superlattices

    Science.gov (United States)

    Schwickert, M. M.; Coehoorn, R.; Tomaz, M. A.; Mayo, E.; Lederman, D.; O'brien, W. L.; Lin, Tao; Harp, G. R.

    1998-06-01

    Epitaxial Fe/V(001) multilayers are studied both experimentally and by theoretical calculations. Sputter-deposited epitaxial films are characterized by x-ray diffraction, magneto-optical Kerr effect, and x-ray magnetic circular dichroism. These results are compared with first-principles calculations modeling different amounts of interface interdiffusion. The exchange coupling across the V layers is observed to oscillate, with antiferromagnetic peaks near the V layer thicknesses tV~22, 32, and 42 Å. For all films including superlattices and alloys, the average V magnetic moment is antiparallel to that of Fe. The average V moment increases slightly with increasing interdiffusion at the Fe/V interface. Calculations modeling mixed interface layers and measurements indicate that all V atoms are aligned with one another for tV<~15 Å, although the magnitude of the V moment decays toward the center of the layer. This ``transient ferromagnetic'' state arises from direct (d-d) exchange coupling between V atoms in the layer. It is argued that the transient ferromagnetism suppresses the first antiferromagnetic coupling peak between Fe layers, expected to occur at tV~12 Å.

  12. Ferromagnetism in doped or undoped spintronics nanomaterials

    Science.gov (United States)

    Qiang, You

    2010-10-01

    Much interest has been sparked by the discovery of ferromagnetism in a range of oxide doped and undoped semiconductors. The development of ferromagnetic oxide semiconductor materials with giant magnetoresistance (GMR) offers many advantages in spintronics devices for future miniaturization of computers. Among them, TM-doped ZnO is an extensively studied n-type wide-band-gap (3.36 eV) semiconductor with a tremendous interest as future mini-computer, blue light emitting, and solar cells. In this talk, Co-doped ZnO and Co-doped Cu2O semiconductor nanoclusters are successfully synthesized by a third generation sputtering-gas-aggregation cluster technique. The Co-doped nanoclusters are ferromagnetic with Curie temperature above room temperature. Both of Co-doped nanoclusters show positive magnetoresistance (PMR) at low temperature, but the amplitude of the PMRs shows an anomalous difference. For similar Co doping concentration at 5 K, PMR is greater than 800% for Co-doped ZnO but only 5% for Co-doped Cu2O nanoclusters. Giant PMR in Co-doped ZnO which is attributed to large Zeeman splitting effect has a linear dependence on applied magnetic field with very high sensitivity, which makes it convenient for the future spintronics applications. The small PMR in Co-doped Cu2O is related to its vanishing density of states at Fermi level. Undoped Zn/ZnO core-shell nanoparticle gives high ferromagnetic properties above room temperature due to the defect induced magnetization at the interface.

  13. Fractal effects on excitations in diluted ferromagnets

    International Nuclear Information System (INIS)

    Kumar, D.

    1981-08-01

    The low energy spin-wave like excitations in diluted ferromagnets near percolation threshold are studied. For this purpose an explicit use of the fractal model for the backbone of the infinite percolating cluster due to Kirkpatrick is made. Three physical effects are identified, which cause the softening of spin-waves as the percolation point is approached. The importance of fractal effects in the calculation of density of states and the low temperature thermodynamics is pointed out. (author)

  14. Raman characterization of bulk ferromagnetic nanostructured graphite

    International Nuclear Information System (INIS)

    Pardo, Helena; Divine Khan, Ngwashi; Faccio, Ricardo; Araújo-Moreira, F.M.; Fernández-Werner, Luciana

    2012-01-01

    Raman spectroscopy was used to characterize bulk ferromagnetic graphite samples prepared by controlled oxidation of commercial pristine graphite powder. The G:D band intensity ratio, the shape and position of the 2D band and the presence of a band around 2950 cm -1 showed a high degree of disorder in the modified graphite sample, with a significant presence of exposed edges of graphitic planes as well as a high degree of attached hydrogen atoms.

  15. Anomalous hall effect in ferromagnetic semiconductors

    Czech Academy of Sciences Publication Activity Database

    Jungwirth, Tomáš; Niu, Q.; MacDonald, A. H.

    2002-01-01

    Roč. 88, č. 20 (2002), s. 207208-1-207208-4 ISSN 0031-9007 R&D Projects: GA ČR GA202/02/0912; GA MŠk OC P5.10 Institutional research plan: CEZ:AV0Z1010914 Keywords : ferromagnetic semiconductors * anomalous Hall effect Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 7.323, year: 2002

  16. Magnon squeezing states in a ferromagnet

    International Nuclear Information System (INIS)

    Wang Junfeng; Cheng Ze; Ping Yunxia; Wan Jinyin; Zhang Yanmin

    2006-01-01

    In this Letter we discuss squeezing state of magnon in ferromagnet, which permits a reduction in the quantum fluctuation of the spin component to below the zero-point quantum noise level of coherent magnon states. We investigate the generation of squeezed magnon state through calculating the expectation values of spin component fluctuation. The mean field theory is introduced in dealing with the nonlinear interaction terms of Hamiltonian of magnon system

  17. Quiet Moment around the Campfire

    Centers for Disease Control (CDC) Podcasts

    2014-06-18

    Byron Breedlove reads his essay, "Quiet Moment around the Campfire," about the art of Frederic Remington and the transmission of pathogens as frontiers expand.  Created: 6/18/2014 by National Center for Emerging and Zoonotic Infectious Diseases (NCEZID).   Date Released: 6/19/2014.

  18. Particle electric dipole-moments

    Energy Technology Data Exchange (ETDEWEB)

    Pendlebury, J M [Sussex Univ., Brighton (United Kingdom)

    1997-04-01

    The incentive to detect particle electric dipole-moments, as a window on time-reversal violation, remains undiminished. Efforts to improve the measurements for the neutron, the electron and some nuclei are still making rapid progress as more powerful experimental methods are brought to bear. A new measurement for the neutron at ILL is presented. (author). 7 refs.

  19. Moment of Inertia by Differentiation

    Science.gov (United States)

    Rizcallah, Joseph A.

    2015-01-01

    The calculation of the moment of inertia of an extended body, as presented in standard introductory-level textbooks, involves the evaluation of a definite integral--an operation often not fully mastered by beginners, let alone the conceptual difficulties it presents, even to the advanced student, in understanding and setting up the integral in the…

  20. Unteachable Moments and Pedagogical Relationships

    Science.gov (United States)

    Wang, Hongyu

    2016-01-01

    This paper discusses how Julia Kristeva's theory can inform our understanding of unteachable moments. It proposes a pedagogical relationship that can contain breakdowns of meanings and work toward breakthroughs to new awareness, particularly related to social justice pedagogy in teacher education. First, one example from the author's own teaching…

  1. Moment Distributions of Phase Type

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    2011-01-01

    Moment distributions of phase-type and matrix-exponential distributions are shown to remain within their respective classes. We provide a probabilistic phase-type representation for the former case and an alternative representation, with an analytically appealing form, for the latter. First order...

  2. Moment methods and Lanczos methods

    International Nuclear Information System (INIS)

    Whitehead, R.R.

    1980-01-01

    In contrast to many of the speakers at this conference I am less interested in average properties of nuclei than in detailed spectroscopy. I will try to show, however, that the two are very closely connected and that shell-model calculations may be used to give a great deal of information not normally associated with the shell-model. It has been demonstrated clearly to us that the level spacing fluctuations in nuclear spectra convey very little physical information. This is true when the fluctuations are averaged over the entire spectrum but not if one's interest is in the lowest few states, whose spacings are relatively large. If one wishes to calculate a ground state (say) accurately, that is with an error much smaller than the excitation energy of the first excited state, very high moments, μ/sub n/, n approx. 200, are needed. As I shall show, we use such moments as a matter of course, albeit without actually calculating them; in fact I will try to show that, if at all possible, the actual calculations of moments is to be avoided like the plague. At the heart of the new shell-model methods embodied in the Glasgow shell-model program and one or two similar ones is the so-called Lanczos method and this, it turns out, has many deep and subtle connections with the mathematical theory of moments. It is these connections that I will explore here

  3. Tunable Magnon Weyl Points in Ferromagnetic Pyrochlores.

    Science.gov (United States)

    Mook, Alexander; Henk, Jürgen; Mertig, Ingrid

    2016-10-07

    The dispersion relations of magnons in ferromagnetic pyrochlores with Dzyaloshinskii-Moriya interaction are shown to possess Weyl points, i. e., pairs of topologically nontrivial crossings of two magnon branches with opposite topological charge. As a consequence of their topological nature, their projections onto a surface are connected by magnon arcs, thereby resembling closely Fermi arcs of electronic Weyl semimetals. On top of this, the positions of the Weyl points in reciprocal space can be tuned widely by an external magnetic field: rotated within the surface plane, the Weyl points and magnon arcs are rotated as well; tilting the magnetic field out of plane shifts the Weyl points toward the center Γ[over ¯] of the surface Brillouin zone. The theory is valid for the class of ferromagnetic pyrochlores, i. e., three-dimensional extensions of topological magnon insulators on kagome lattices. In this Letter, we focus on the (111) surface, identify candidates of established ferromagnetic pyrochlores which apply to the considered spin model, and suggest experiments for the detection of the topological features.

  4. Modeling and calculation of RKKY exchange coupling to explain Ti-vacancy-induced ferromagnetism in Ta-doped TiO2

    Science.gov (United States)

    Majidi, Muhammad Aziz; Bupu, Annamaria; Fauzi, Angga Dito

    2017-12-01

    We present a theoretical study on Ti-vacancy-induced ferromagnetism in anatase TiO2. A recent experimental study has revealed room temperature ferromagnetism in Ta-doped anatase TiO2thin films (Rusydi et al., 2012) [7]. Ta doping assists the formation of Ti vacancies which then induce the formation of localized magnetic moments around the Ti vacancies. As neighboring Ti vacancies are a few unit cells apart, the ferromagnetic order is suspected to be mediated by itinerant electrons. We propose that such an electron-mediated ferromagnetism is driven by Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange interaction. To examine our hypothesis, we construct a tight-binding based model Hamiltonian for the anatase TiO2 system. We calculate the RKKY exchange coupling constant of TiO2 as a function of distance between local magnetic moments at various temperatures. We model the system by taking only the layer containing a unit of TiO2, at which the Ti vacancy is believed to form, as our effective two-dimensional unit cell. Our model incorporates the Hubbard repulsive interactions between electrons occupying Ti d orbitals treated within mean-field approximation. The density of states profile resulting from the model captures the relevant electronic properties of TiO2, such as the energy gap of 3.4 eV and the n-type character, which may be a measure of the adequacy of the model. The calculated RKKY coupling constant shows that the ferromagnetic coupling extends up to 3-4 unit cells and enhances slightly as temperature is increased from 0 to 400 K. These results support our hypothesis that the ferromagnetism of this system is driven by RKKY mechanism.

  5. GdCuMg with ZrNiAl-type structure. An 82.2 K ferromagnet

    Energy Technology Data Exchange (ETDEWEB)

    Stein, Sebastian; Heletta, Lukas; Poettgen, Rainer [Muenster Univ. (Germany). Inst. fuer Anorganische und Analytische Chemie

    2017-08-01

    GdCuMg has been synthesized by induction-melting of the elements in a sealed niobium ampoule followed by annealing in a muffle furnace. The sample was studied by powder and single crystal X-ray diffraction: ZrNiAl type, P anti 62m (a=749.2(4), c=403.3(1) pm), wR2=0.0242, 315 F{sup 2} values and 15 variables. Temperature dependent magnetic susceptibility measurements have revealed an experimental magnetic moment of 8.54(1) μ{sub B} per Gd atom. GdCuMg orders ferromagnetically below T{sub C}=82.2(5) K and based on the magnetization isotherms it can be classified as a soft ferromagnet.

  6. Pressure-induced itinerant electron metamagnetism in UCo0.995Os0.005Al ferromagnet

    Science.gov (United States)

    Mushnikov, N. V.; Andreev, A. V.; Arnold, Z.

    2018-05-01

    The effect of external hydrostatic pressure on magnetic properties is studied for the UCo0.995Os0.005Al single crystal. At ambient pressure, the ground state is ferromagnetic. Even lowest applied pressure 0.11 GPa is sufficient to suppress ferromagnetism. A sharp metamagnetic transition is observed only in magnetic fields along the c axis of the crystal, similar to previously studied itinerant electron metamagnet UCoAl. Temperature dependence of the susceptibility for various pressures shows a broad maximum at Tmax 20 K. The experimental data are analyzed with the theory of itinerant electron metamagnetism, which considers anisotropic thermal fluctuations of the uranium magnetic moment. The observed pressure dependence of the susceptibility at Tmax and the temperature for the disappearance of the first-order metamagnetic transition are explained with the theory.

  7. Intrinsic and Extrinsic Ferromagnetism in Co-Doped Indium Tin Oxide Revealed Using X-Ray Magnetic Circular Dichroism

    Directory of Open Access Journals (Sweden)

    A. M. H. R. Hakimi

    2017-01-01

    Full Text Available The effects of high-temperature annealing on ferromagnetic Co-doped Indium Tin Oxide (ITO thin films have been investigated using X-ray diffraction (XRD, magnetometry, and X-Ray Magnetic Circular Dichroism (XMCD. Following annealing, the magnetometry results indicate the formation of Co clusters with a significant increase in the saturation magnetization of the thin films arising from defects introduced during cluster formation. However, sum rule analysis of the element-specific XMCD results shows that the magnetic moment at the Co sites is reduced after annealing. The effects of annealing demonstrate that the ferromagnetism observed in the as-deposited Co-doped ITO films arises from intrinsic defects and cannot be related to the segregation of metallic Co clusters.

  8. Influence of crossed fields in structures combining large grain, bulk (RE)BCO superconductors and soft ferromagnetic discs

    International Nuclear Information System (INIS)

    Philippe, M P; Fagnard, J F; Wéra, L; Vanderheyden, B; Vanderbemden, P; Morita, M; Nariki, S; Teshima, H; Caps, H

    2016-01-01

    Bulk (RE)BCO superconductors are able to trap record magnetic fields and can be used as powerful permanent magnets in various engineering applications such as rotating machines and magnetic bearings. When such superconducting (SC) “trapped field magnets” are combined to a ferromagnetic (FM) disc, the total magnetic moment is increased with respect to that of the superconductor alone. In the present work, we study experimentally the magnetic behaviour of such hybrid FM/SC structures when they are subjected to cycles of applied field that are orthogonal to their permanent magnetization, i.e. a “crossed-field” configuration. Experimental results show that the usual “crossed-field demagnetization” caused by the cycles of transverse field is strongly reduced in the presence of the ferromagnet. (paper)

  9. Maximal Electric Dipole Moments of Nuclei with Enhanced Schiff Moments

    CERN Document Server

    Ellis, John; Pilaftsis, Apostolos

    2011-01-01

    The electric dipole moments (EDMs) of heavy nuclei, such as 199Hg, 225Ra and 211Rn, can be enhanced by the Schiff moments induced by the presence of nearby parity-doublet states. Working within the framework of the maximally CP-violating and minimally flavour-violating (MCPMFV) version of the MSSM, we discuss the maximal values that such EDMs might attain, given the existing experimental constraints on the Thallium, neutron and Mercury EDMs. The maximal EDM values of the heavy nuclei are obtained with the help of a differential-geometrical approach proposed recently that enables the maxima of new CP-violating observables to be calculated exactly in the linear approximation. In the case of 225Ra, we find that its EDM may be as large as 6 to 50 x 10^{-27} e.cm.

  10. Ga vacancy induced ferromagnetism enhancement and electronic structures of RE-doped GaN

    International Nuclear Information System (INIS)

    Zhong Guohua; Zhang Kang; He Fan; Ma Xuhang; Lu Lanlan; Liu Zhuang; Yang Chunlei

    2012-01-01

    Because of their possible applications in spintronic and optoelectronic devices, GaN dilute magnetic semiconductors (DMSs) doped by rare-earth (RE) elements have attracted much attention since the high Curie temperature was obtained in RE-doped GaN DMSs and a colossal magnetic moment was observed in the Gd-doped GaN thin film. We have systemically studied the GaN DMSs doped by RE elements (La, Ce-Yb) using the full-potential linearized augmented plane wave method within the framework of density functional theory and adding the considerations of the electronic correlation and the spin-orbital coupling effects. We have studied the electronic structures of DMSs, especially for the contribution from f electrons. The origin of magnetism, magnetic interaction and the possible mechanism of the colossal magnetic moment were explored. We found that, for materials containing f electrons, electronic correlation was usually strong and the spin-orbital coupling was sometimes crucial in determining the magnetic ground state. It was found that GaN doped by La was non-magnetic. GaN doped by Ce, Nd, Pm, Eu, Gd, Tb and Tm are stabilized at antiferromagnetic phase, while GaN doped by other RE elements show strong ferromagnetism which is suitable materials for spintronic devices. Moreover, we have identified that the observed large enhancement of magnetic moment in GaN is mainly caused by Ga vacancies (3.0μB per Ga vacancy), instead of the spin polarization by magnetic ions or originating from N vacancies. Various defects, such as substitutional Mg for Ga, O for N under the RE doping were found to bring a reduction of ferromagnetism. In addition, intermediate bands were observed in some systems of GaN:RE and GaN with intrinsic defects, which possibly opens the potential application of RE-doped semiconductors in the third generation high efficiency photovoltaic devices.

  11. First-principles study on half-metallic ferromagnetic properties of Zn{sub 1-x}V{sub x}Se ternary alloys

    Energy Technology Data Exchange (ETDEWEB)

    Khatta, Swati; Tripathi, S.K.; Prakash, Satya [Panjab University, Central of Advanced Study in Physics, Department of Physics, Chandigarh (India)

    2017-09-15

    The spin-polarised density functional theory along with self-consistent plane-wave pseudopotential is used to investigate the half-metallic ferromagnetic properties of ternary alloys Zn{sub 1-x}V{sub x}Se. The generalized gradient approximation is used for exchange-correlation potential. The equilibrium lattice constants, bulk modulus, and its derivatives are calculated. The calculated spin-polarised energy-band structures reveal that these alloys are half-metallic for x = 0.375 and 0.50 and nearly half-metallic for other values of x. The estimated direct and indirect bandgaps may be useful for the magneto-optical absorption experiments. It is found that there is strong Zn 4s, Se 4p, and V 3d orbital hybridization in the conduction bands of both the spins, while Se 4p and V 3d orbital hybridization predominates in the valence bands of both the spins. The s, p-d, and p-d orbital hybridization reduces the local magnetic moment of V atoms and small local magnetic moments are produced on Zn and Se atoms which get coupled with V atoms in ferromagnetic and antiferromagnetic phases, respectively. The conduction and valence-band-edge splittings and exchange constants predict the ferromagnetism in these alloys. The conduction band-impurity (s and p-d) exchange interaction is more significant for ferromagnetism in these alloys than the valence band-impurity (p-d) exchange interaction. (orig.)

  12. Ab-initio calculation and experimental observation of room temperature ferromagnetism in 50 keV nitrogen implanted rutile TiO2

    Science.gov (United States)

    Luitel, Homnath; Chakrabarti, Mahuya; Sarkar, A.; Dechoudhury, S.; Bhowmick, D.; Naik, V.; Sanyal, D.

    2018-02-01

    Room temperature magnetic properties of 50 keV N4+ ion beam implanted rutile TiO2 have been theoretically and experimentally studied. Ab-initio calculation under the frame work of density functional theory has been carried out to study the magnetic properties of the different possible nitrogen related defects in TiO2. Spin polarized density of states calculation suggests that both Ninst and NO can induce ferromagnetic ordering in rutile TiO2. In both cases the 2p orbital electrons of nitrogen atom give rise to the magnetic moment in TiO2. The possibility of the formation of N2 molecule in TiO2 system is also studied but in this case no significant magnetic moment has been observed. The magnetic measurements, using SQUID magnetometer, results a ferromagnetic ordering even at room temperature for the 50 keV N4+ ion beam implanted rutile TiO2.

  13. An electromagnetically actuated fiber optic switch using magnetized ferromagnetic materials

    Science.gov (United States)

    Pandojirao-S, Praveen; Dhaubanjar, Naresh; Phuyal, Pratibha C.; Chiao, Mu; Chiao, J.-C.

    2008-03-01

    This paper presents the design, fabrication and testing of a fiber optic switch actuated electromagnetically. The ferromagnetic gel coated optical fiber is actuated using external electromagnetic fields. The ferromagnetic gel consists of ferromagnetic powders dispersed in epoxy. The fabrication utilizes a simple cost-effective coating setup. A direct fiberto-fiber alignment eliminates the need for complementary optical parts and the displacement of fiber switches the laser coupling. The magnetic characteristics of magnetized ferromagnetic materials are performed using alternating gradient magnetometer and the magnetic hysteresis curves are measured for different ferromagnetic materials including iron, cobalt, and nickel. Optical fiber switches with various fiber lengths are actuated and their static and dynamic responses for the same volume of ferromagnetic gel are summarized. The highest displacement is 1.345 mm with an input current of 260mA. In this paper, the performance of fiber switches with various coating materials is presented.

  14. Ferromagnetism appears in nitrogen implanted nanocrystalline diamond films

    Energy Technology Data Exchange (ETDEWEB)

    Remes, Zdenek [Institute of Physics ASCR v.v.i., Cukrovarnicka 10, 162 00 Prague 6 (Czech Republic); Sun, Shih-Jye, E-mail: sjs@nuk.edu.tw [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Varga, Marian [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Chou, Hsiung [Department of Physics, National Sun Yat-Sen University, Kaohsiung 804, Taiwan (China); Hsu, Hua-Shu [Department of Applied Physics, National Pingtung University of Education, Pingtung 900, Taiwan (China); Kromka, Alexander [Department of Applied Physics, National University of Kaohsiung, Kaohsiung 811, Taiwan (China); Horak, Pavel [Nuclear Physics Institute, 250 68 Rez (Czech Republic)

    2015-11-15

    The nanocrystalline diamond films turn to be ferromagnetic after implanting various nitrogen doses on them. Through this research, we confirm that the room-temperature ferromagnetism of the implanted samples is derived from the measurements of magnetic circular dichroism (MCD) and superconducting quantum interference device (SQUID). Samples with larger crystalline grains as well as higher implanted doses present more robust ferromagnetic signals at room temperature. Raman spectra indicate that the small grain-sized samples are much more disordered than the large grain-sized ones. We propose that a slightly large saturated ferromagnetism could be observed at low temperature, because the increased localization effects have a significant impact on more disordered structure. - Highlights: • Nitrogen implanted nanocrystalline diamond films exhibit ferromagnetism at room temperature. • Nitrogen implants made a Raman deviation from the typical nanocrystalline diamond films. • The ferromagnetism induced from the structure distortion is dominant at low temperature.

  15. Biological Petri Nets

    CERN Document Server

    Wingender, E

    2011-01-01

    It was suggested some years ago that Petri nets might be well suited to modeling metabolic networks, overcoming some of the limitations encountered by the use of systems employing ODEs (ordinary differential equations). Much work has been done since then which confirms this and demonstrates the usefulness of this concept for systems biology. Petri net technology is not only intuitively understood by scientists trained in the life sciences, it also has a robust mathematical foundation and provides the required degree of flexibility. As a result it appears to be a very promising approach to mode

  16. Reconfiguration of distribution nets

    International Nuclear Information System (INIS)

    Latorre Bayona, Gerardo; Angarita Marquez, Jorge Luis

    2000-01-01

    Starting of the location of the reconfiguration problem inside the context of the operation of distribution nets, of the quality indicators definition and of the presentation of the alternatives more used for reduction of technical losses, they are related diverse reconfiguration methodologies proposed in the technical literature, pointing out their three principals limitations; also are presents the results of lost obtained starting from simulation works carried out in distribution circuits of the ESSA ESP, which permitting to postulate the reconfiguration of nets like an excellent alternative to reduce technical losses

  17. NET system integration

    International Nuclear Information System (INIS)

    Farfaletti-Casali, F.; Mitchell, N.; Salpietro, E.; Buzzi, U.; Gritzmann, P.

    1985-01-01

    The NET system integration procedure is the process by which the requirements of the various Tokamak machine design areas are brought together to form a compatible machine layout. Each design area produces requirements which generally allow components to be built at minimum cost and operate with minimum technical risk, and the final machine assembly should be achieved with minimum departure from these optimum designs. This is carried out in NET by allowing flexibility in the maintenance and access methods to the machine internal components which must be regularly replaced by remote handling, in segmentation of these internal components and in the number of toroidal field coils

  18. Tunnel barrier and noncollinear magnetization effects on shot noise in ferromagnetic/semiconductor/ferromagnetic heterojunctions

    International Nuclear Information System (INIS)

    An Xingtao; Liu Jianjun

    2008-01-01

    Based on the scattering approach, we investigate transport properties of electrons in a one-dimensional waveguide that contains a ferromagnetic/semiconductor/ferromagnetic heterojunction and tunnel barriers in the presence of Rashba and Dresselhaus spin-orbit interactions. We simultaneously consider significant quantum size effects, quantum coherence, Rashba and Dresselhaus spin-orbit interactions and noncollinear magnetizations. It is found that the tunnel barrier plays a decisive role in the transmission coefficient and shot noise of the ballistic spin electron transport through the heterojunction. When the small tunnel barriers are considered, the transport properties of electrons are quite different from those without tunnel barriers

  19. Modelling characteristics of ferromagnetic cores with the influence of temperature

    International Nuclear Information System (INIS)

    Górecki, K; Rogalska, M; Zarȩbski, J; Detka, K

    2014-01-01

    The paper is devoted to modelling characteristics of ferromagnetic cores with the use of SPICE software. Some disadvantages of the selected literature models of such cores are discussed. A modified model of ferromagnetic cores taking into account the influence of temperature on the magnetizing characteristics and the core losses is proposed. The form of the elaborated model is presented and discussed. The correctness of this model is verified by comparing the calculated and the measured characteristics of the selected ferromagnetic cores.

  20. A method for measuring exchange stiffness in ferromagnetic films

    International Nuclear Information System (INIS)

    Girt, Erol; Huttema, W.; Montoya, E.; Kardasz, B.; Eyrich, C.; Heinrich, B.; Mryasov, O. N.; Dobin, A. Yu.; Karis, O.

    2011-01-01

    An exchange stiffness, A ex , in ferromagnetic films is obtained by fitting the M(H) dependence of two ferromagnetic layers antiferromagnetically coupled across a nonmagnetic spacer layer with a simple micromagnetic model. In epitaxial and textured structures this method allows measuring A ex between the crystallographic planes perpendicular to the growth direction of ferromagnetic films. Our results show that A ex between [0001] planes in textured Co grains is 1.54 ± 0.12 x 10 -11 J/m.

  1. Room temperature ferromagnetism in ZnO prepared by microemulsion

    Directory of Open Access Journals (Sweden)

    Qingyu Xu

    2011-09-01

    Full Text Available Clear room temperature ferromagnetism has been observed in ZnO powders prepared by microemulsion. The O vacancy (VO clusters mediated by the VO with one electron (F center contributed to the ferromagnetism, while the isolated F centers contributed to the low temperature paramagnetism. Annealing in H2 incorporated interstitial H (Hi in ZnO, and removed the isolated F centers, leading to the suppression of the paramagnetism. The ferromagnetism has been considered to originate from the VO clusters mediated by the Hi, leading to the enhancement of the coercivity. The ferromagnetism disappeared after annealing in air due to the reduction of Hi.

  2. Ferromagnetic pairing states on two-coupled chains

    International Nuclear Information System (INIS)

    Tanaka, Akinori

    2008-01-01

    We propose a concrete model which exhibits ferromagnetism and electron-pair condensation simultaneously. The model is defined on two chains and consists of the electron hopping term, the on-site Coulomb repulsion and a ferromagnetic interaction which describes ferromagnetic coupling between two electrons, one on a bond in a chain and the other on a site in the other chain. It is rigorously shown that the model has fully-polarized ferromagnetic pairing ground states. The higher dimensional version of the model is also presented

  3. Coloured Petri Nets

    CERN Document Server

    Jensen, Kurt

    2009-01-01

    Coloured Petri Nets (CPN) is a graphical language for modelling and validating concurrent and distributed systems, and other systems in which concurrency plays a major role. This book introduces the constructs of the CPN modelling language and presents the related analysis methods. It provides a comprehensive road map for the practical use of CPN.

  4. Safety nets or straitjackets?

    DEFF Research Database (Denmark)

    Ilsøe, Anna

    2012-01-01

    Does regulation of working hours at national and sector level impose straitjackets, or offer safety nets to employees seeking working time flexibility? This article compares legislation and collective agreements in the metal industries of Denmark, Germany and the USA. The industry has historically...

  5. Neuronal nets in robotics

    International Nuclear Information System (INIS)

    Jimenez Sanchez, Raul

    1999-01-01

    The paper gives a generic idea of the solutions that the neuronal nets contribute to the robotics. The advantages and the inconveniences are exposed that have regarding the conventional techniques. It also describe the more excellent applications as the pursuit of trajectories, the positioning based on images, the force control or of the mobile robots management, among others

  6. Net4Care platform

    DEFF Research Database (Denmark)

    2012-01-01

    , that in turn enables general practitioners and clinical staff to view observations. Use the menus above to explore the site's information resources. To get started, follow the short Hello, World! tutorial. The Net4Care project is funded by The Central Denmark Region and EU via Caretech Innovation....

  7. Coloured Petri Nets

    DEFF Research Database (Denmark)

    Jensen, Kurt; Kristensen, Lars Michael

    Coloured Petri Nets (CPN) is a graphical language for modelling and validating concurrent and distributed systems, and other systems in which concurrency plays a major role. The development of such systems is particularly challenging because of inherent intricacies like possible nondeterminism an...

  8. Game Theory .net.

    Science.gov (United States)

    Shor, Mikhael

    2003-01-01

    States making game theory relevant and accessible to students is challenging. Describes the primary goal of GameTheory.net is to provide interactive teaching tools. Indicates the site strives to unite educators from economics, political and computer science, and ecology by providing a repository of lecture notes and tests for courses using…

  9. BacillusRegNet

    DEFF Research Database (Denmark)

    Misirli, Goksel; Hallinan, Jennifer; Röttger, Richard

    2014-01-01

    As high-throughput technologies become cheaper and easier to use, raw sequence data and corresponding annotations for many organisms are becoming available. However, sequence data alone is not sufficient to explain the biological behaviour of organisms, which arises largely from complex molecular...... the associated BacillusRegNet website (http://bacillus.ncl.ac.uk)....

  10. Boom Booom Net Radio

    DEFF Research Database (Denmark)

    Grimshaw, Mark Nicholas; Yong, Louisa; Dobie, Ian

    1999-01-01

    of an existing Internet radio station; Boom Booom Net Radio. Whilst necessity dictates some use of technology-related terminology, wherever possible we have endeavoured to keep such jargon to a minimum and to either explain it in the text or to provide further explanation in the appended glossary....

  11. The Critical Moment of Transition

    DEFF Research Database (Denmark)

    Svalgaard, Lotte

    2018-01-01

    By providing a holding environment to acknowledge sensitivities and address emotions, leadership programs prove to be powerful spaces for increasing self- and social awareness. However, the challenge is for one to maintain the newly gained self- and social awareness after leaving the holding...... environment and entering a context characterized by activity and performance. This is a frequently debated challenge for both academics and providers of management learning. Yet, critical moments in this transition remain under-exposed and under-researched. The contribution of this article is a research study......—within the context of an international MBA program—of MBA students applying their knowledge from a Leadership Stream in an international consultancy project. This article contributes to the theory and practice of management learning by providing a lens through which subjective experience of critical moments...

  12. Moment of truth for CMS

    CERN Multimedia

    2006-01-01

    One of the first events reconstructed in the Muon Drift Tubes, the Hadron Calorimeter and elements of the Silicon Tracker (TK) at 3 Tesla. The atmosphere in the CMS control rooms was electric. Everbody was at the helm for the first full-scale testing of the experiment. This was a crunch moment for the entire collaboration. On Tuesday, 22 August the magnet attained almost its nominal power of 4 Tesla! At the same moment, in a tiny improvised control room, the physicists were keyed up to test the entire detector system for the first time. The first cosmic ray tracks appeared on their screens in the week of 15 August. The tests are set to continue for several weeks more until the first CMS components are lowered into their final positions in the cavern.

  13. Moment Distributions of Phase Type

    DEFF Research Database (Denmark)

    Bladt, Mogens; Nielsen, Bo Friis

    In this paper we prove that the class of distributions on the positive reals with a rational Laplace transform, also known as matrix-exponential distributions, is closed under formation of moment distributions. In particular, the results are hence valid for the well known class of phase-type dist...... alternative representation in terms of sub{intensity matrices. Finally we are able to nd explicit expressions for both the Lorenz curve and the Gini index....

  14. Electric Dipole Moments of Hadrons

    OpenAIRE

    Wirzba, Andreas

    2016-01-01

    A nonzero electric dipole moment (EDM) of the neutron, proton, deuteron, helion or any finite system necessarily involves the breaking of a symmetry, either by the presence of external fields (leading to the case of induced EDMs) or explicitly by the breaking of the discrete parity and time-reflection symmetries in the case of permanent EDMs. Recent - and in the case of the deuteron even unpublished - results for the relevant matrix elements of nuclear EDM operators are presented and the rel...

  15. Half-metallicity and ferromagnetism of TcX (X=C, Si and Ge) in zinc blende structure

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yong [College of Science, Yanshan University, Qinhuangdao 066004 (China); Physics Department, Brock University, St. Catharines, ON, Canada L2S 3A1 (Canada); Xing, Yue [College of Science, Yanshan University, Qinhuangdao 066004 (China); Bose, S.K., E-mail: sbose@brocku.ca [Physics Department, Brock University, St. Catharines, ON, Canada L2S 3A1 (Canada); Zhao, Yong-Hong [Department of Physics, Sichuan Normal University, Chengdu 610068 (China)

    2013-02-15

    We report results of a first-principles density-functional study of three binary transition-metal compounds TcX (X=C, Si and Ge) in the hypothetical cubic zinc blende (ZB) structure. Our calculations are based on the full potential linear augmented plane wave (FP-LAPW) plus local orbitals method, together with generalized gradient approximation for the exchange-correlation potential. Half-metallic (HM) ferromagnetism is observed in these binary compounds for their optimized cell volumes. In the HM state, these compounds possess an integer magnetic moment (1.000{mu}{sub B}) per formula unit, which is one of the important characteristics of half-metallic ferromagnets (HMFs). The ferromagnetic (FM) state is found to be stable for ZB TcC, TcSi and TcGe against the nonmagnetic (NM) and antiferromagnetic (AFM) states. Calculations show that half-metallicity can be maintained for a wide range of lattice constants in these binary compounds. Density functional calculations of exchange interactions and the Curie temperatures reveal similar trends for the three compounds with respect to the lattice parameter. These compounds are compatible with the traditional semiconductors, and could be useful in spin-electronics and other applications. The most important aspect of this work is to explore the possibility of not only magnetism, but HM ferromagnetism in compounds involving NM elements and 4d transition element Tc. - Highlights: Black-Right-Pointing-Pointer We study magnetism of the compounds TcSi, TcC, and TcGe. Black-Right-Pointing-Pointer These compounds, with nonmagnetic constituents, are found to be ferromagnetic. Black-Right-Pointing-Pointer They show robust half-metallicity in zinc blende structure. Black-Right-Pointing-Pointer Estimated Curie temperatures suggest that synthesis of these compounds is worth pursuing.

  16. Ultrafast Magnetism of Multi-component Ferromagnets and Ferrimagnets on the Time Scale of the Exchange Interaction

    Science.gov (United States)

    Radu, Ilie

    2012-02-01

    Revealing the ultimate speed limit at which magnetic order can be controlled, is a fundamental challenge of modern magnetism having far reaching implications for the magnetic recording industry [1]. Exchange interaction is the strongest force in magnetism, being ultimately responsible for ferromagnetic or antiferromagnetic spin order. How do spins react after being optically excited on a timescale of or even faster than the exchange interaction? Here, we demonstrate that femtosecond (fs) measurements of ferrimagnetic and ferromagnetic alloys using X-ray magnetic circular dichroism provide revolutionary new insights into the problem of ultrafast magnetism on timescales pertinent to the exchange interaction. In particular, we show that upon fs optical excitation the ultrafast spin reversal of GdFeCo - a material with antiferromagnetic coupling of spins - occurs via a transient ferromagnetic state [2]. The latter emerges due to different dynamics of the Gd and Fe magnetic moments: Gd switches within 1.5 ps while it takes only 300 fs for Fe. Thus, by using a single fs laser pulse one can force the spin system to evolve via an energetically unfavorable way and temporarily switch from an antiferromagnetic to a ferromagnetic type of ordering. In order to understand whether the observation of this temporarily decoupled and element-specific dynamics is a general phenomenon or just something strictly related to the case of ferrimagnetic GdFeCo, we have investigated the demagnetization of the archetypal ferromagnetic NiFe alloys. Essentially, we observe the same distinct magnetization dynamics of the constituent magnetic moments: Ni demagnetizes within ˜300 fs being much faster than the demagnetization of Fe of ˜800 fs. This distinct demagnetization behavior leads to an apparent decoupling of the Fe and Ni magnetic moments on a few hundreds of fs time scale, despite the strong exchange interaction of 260meV (˜16 fs) that couples them. These observations supported by

  17. Ferromagnetism and antiferromagnetism coexistence in SrRu1-xMnxO3: Density functional calculation

    International Nuclear Information System (INIS)

    Hadipour, H.; Fallahi, S.; Akhavan, M.

    2011-01-01

    We have calculated the electronic structure of SrRu 1-x Mn x O 3 using the full potential linearized augmented plane wave method by LSDA and LSDA+U. The antiparallel alignment between the Mn and Ru ions are consistent with the competition between ferromagnetism and antiferromagnetism in the low Mn-doped polycrystalline samples. This is in contrast to the appearance of quantum critical point and FM and AFM transitions in the single crystal measurement. Our results show that the discrepancy between different experimental phase diagrams is related to the conditions of sample preparation and also the difference between the degree of magnetic interactions between the Mn and Ru moments. The DOS and the calculated Mn magnetic moment is similar to the magnetic moment of a purely ionic compound with d 3 configuration. The AFM state has band gap of 1.2 eV at the Fermi energy predicting an insulating behavior. -- Graphical abstract: The antiparallel alignment between the Mn and Ru ions are consistent with the competition between ferromagnetism and antiferromagnetism with the formation of a spin glass phase. We have calculated the electronic structure of SrRu 1-x Mn x O 3 using the full potential linearized augmented plane wave method by LSDA and LSDA+U in the range of both low and high Mn-doping for parallel and antiparallel alignments of Ru and Mn moments. In the low Mn-doped polycrystalline samples with tetragonal structure, the AFM hybridization between Mn and the Ru host lattice strongly favors alignment of the Ru moments, and provides an explanation for retaining of high Curie temperature of SrRuO 3 with Mn substitution. Display Omitted Research highlights: → For the low Mn-doping the AFM coupling between Mn and Ru becomes stable. → Results are consistent with the QCP between FM and AFM transitions in single crystals. → In high Mn-doping, electron correlation is important in predicting the insulating behavior.

  18. Magnetic microstructure of nanocrystalline ferromagnets and nanocrystalline systems combining ferromagnetic and antiferromagnetic phases

    Energy Technology Data Exchange (ETDEWEB)

    Loeffler, J.; Wagner, W. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Kostorz, G. [Eidgenoessische Technische Hochschule, Zurich (Switzerland); Wiedenmann, A. [HMI Berlin (Germany)

    1997-09-01

    Magnetic small-angle neutron scattering measurements were performed on nanostructured ferromagnetic materials on the basis of Fe, Ni and Co, produced preferentially by the inert-gas condensation technique, with the aim to determine the magnetic microstructure of mesoscopic small-particle systems. (author) 1 fig., 3 refs.

  19. 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

  20. Spin Transport in Ferromagnetic and Antiferromagnetic Textures

    KAUST Repository

    Akosa, Collins A.

    2016-12-07

    In this dissertation, we provide an accurate description of spin transport in magnetic textures and in particular, we investigate in detail, the nature of spin torque and magnetic damping in such systems. Indeed, as will be further discussed in this thesis, the current-driven velocity of magnetic textures is related to the ratio between the so-called non-adiabatic torque and magnetic damping. Uncovering the physics underlying these phenomena can lead to the optimal design of magnetic systems with improved efficiency. We identified three interesting classes of systems which have attracted enormous research interest (i) Magnetic textures in systems with broken inversion symmetry: We investigate the nature of magnetic damping in non-centrosymmetric ferromagnets. Based on phenomenological and microscopic derivations, we show that the magnetic damping becomes chiral, i.e. depends on the chirality of the magnetic texture. (ii) Ferromagnetic domain walls, skyrmions and vortices: We address the physics of spin transport in sharp disordered magnetic domain walls and vortex cores. We demonstrate that upon spin-independent scattering, the non-adiabatic torque can be significantly enhanced. Such an enhancement is large for vortex cores compared to transverse domain walls. We also show that the topological spin currents owing in these structures dramatically enhances the non-adiabaticity, an effect unique to non-trivial topological textures (iii) Antiferromagnetic skyrmions: We extend this study to antiferromagnetic skyrmions and show that such an enhanced topological torque also exist in these systems. Even more interestingly, while such a non-adiabatic torque inuences the undesirable transverse velocity of ferromagnetic skyrmions, in antiferromagnetic skyrmions, the topological non-adiabatic torque directly determines the longitudinal velocity. As a consequence, scaling down the antiferromagnetic skyrmion results in a much more efficient spin torque.

  1. Room Temperature Ferromagnetic Mn:Ge(001

    Directory of Open Access Journals (Sweden)

    George Adrian Lungu

    2013-12-01

    Full Text Available We report the synthesis of a room temperature ferromagnetic Mn-Ge system obtained by simple deposition of manganese on Ge(001, heated at relatively high temperature (starting with 250 °C. The samples were characterized by low energy electron diffraction (LEED, scanning tunneling microscopy (STM, high resolution transmission electron microscopy (HRTEM, X-ray photoelectron spectroscopy (XPS, superconducting quantum interference device (SQUID, and magneto-optical Kerr effect (MOKE. Samples deposited at relatively elevated temperature (350 °C exhibited the formation of ~5–8 nm diameter Mn5Ge3 and Mn11Ge8 agglomerates by HRTEM, while XPS identified at least two Mn-containing phases: the agglomerates, together with a Ge-rich MnGe~2.5 phase, or manganese diluted into the Ge(001 crystal. LEED revealed the persistence of long range order after a relatively high amount of Mn (100 nm deposited on the single crystal substrate. STM probed the existence of dimer rows on the surface, slightly elongated as compared with Ge–Ge dimers on Ge(001. The films exhibited a clear ferromagnetism at room temperature, opening the possibility of forming a magnetic phase behind a nearly ideally terminated Ge surface, which could find applications in integration of magnetic functionalities on semiconductor bases. SQUID probed the co-existence of a superparamagnetic phase, with one phase which may be attributed to a diluted magnetic semiconductor. The hypothesis that the room temperature ferromagnetic phase might be the one with manganese diluted into the Ge crystal is formulated and discussed.

  2. The generalized spherical model of ferromagnetic films

    International Nuclear Information System (INIS)

    Costache, G.

    1977-12-01

    The D→ infinity of the D-vectorial model of a ferromagnetic film with free surfaces is exactly solved. The mathematical mechanism responsible for the onset of a phase transition in the system is a generalized sticking phenomenon. It is shown that the temperature at which the sticking appears, the transition temperature of the model is monotonously increasing with increasing the number of layers of the film, contrary to what happens in the spherical model with overall constraint. Certain correlation inequalities of Griffiths type are shown to hold. (author)

  3. Ferromagnetic film on a superconducting substrate

    Energy Technology Data Exchange (ETDEWEB)

    Bulaevskii, L. N.; Chudnovsky, E. M.

    2001-01-01

    We study the equilibrium domain structure and magnetic flux around a ferromagnetic film with perpendicular magnetization M{sub 0} on a superconducting (SC) substrate. At 4{pi}M{sub 0}>1; {lambda}{sub L} being the London penetration length.

  4. Ferromagnetic film on a superconducting substrate

    International Nuclear Information System (INIS)

    Bulaevskii, L. N.; Chudnovsky, E. M.

    2001-01-01

    We study the equilibrium domain structure and magnetic flux around a ferromagnetic film with perpendicular magnetization M 0 on a superconducting (SC) substrate. At 4πM 0 c1 the SC is in the Meissner state and the equilibrium domain width in the film, l, scales as (l/4πλ L )=(l N /4πλ L ) 2/3 with the domain width on a normal (nonsuperconducting) substrate, l N /4πλ L >>1; λ L being the London penetration length

  5. Ferromagnetic Film on a Superconducting Substrate

    OpenAIRE

    Bulaevskii, L. N.; Chudnovsky, E. M.

    2000-01-01

    We study the equilibrium domain structure and magnetic flux around a ferromagnetic (FM) film with perpendicular magnetization M_0 on a superconducting (SC) substrate. At 4{\\pi}M_0> 1. Here \\lambda_L is the London penetration length. For 4{\\pi}M_0 > H_{c1} and l_{N} in excess of about 35 {\\lambda}_{L}, the domains are connected by SC vortices. We argue that pinning of vortices by magnetic domains in FM/SC multilayers can provide high critical currents.

  6. Carbon Nanotubes Filled with Ferromagnetic Materials

    Directory of Open Access Journals (Sweden)

    Albrecht Leonhardt

    2010-08-01

    Full Text Available Carbon nanotubes (CNT filled with ferromagnetic metals like iron, cobalt or nickel are new and very interesting nanostructured materials with a number of unique properties. In this paper we give an overview about different chemical vapor deposition (CVD methods for their synthesis and discuss the influence of selected growth parameters. In addition we evaluate possible growth mechanisms involved in their formation. Moreover we show their identified structural and magnetic properties. On the basis of these properties we present different application possibilities. Some selected examples reveal the high potential of these materials in the field of medicine and nanotechnology.

  7. Carbon Nanotubes Filled with Ferromagnetic Materials

    Science.gov (United States)

    Weissker, Uhland; Hampel, Silke; Leonhardt, Albrecht; Büchner, Bernd

    2010-01-01

    Carbon nanotubes (CNT) filled with ferromagnetic metals like iron, cobalt or nickel are new and very interesting nanostructured materials with a number of unique properties. In this paper we give an overview about different chemical vapor deposition (CVD) methods for their synthesis and discuss the influence of selected growth parameters. In addition we evaluate possible growth mechanisms involved in their formation. Moreover we show their identified structural and magnetic properties. On the basis of these properties we present different application possibilities. Some selected examples reveal the high potential of these materials in the field of medicine and nanotechnology. PMID:28883334

  8. Eddy current inspection of mildly ferromagnetic tubing

    International Nuclear Information System (INIS)

    Mayo, W.R.; Carter, J.R.

    1984-02-01

    The past decade has seen the development of eddy current probes for inspection of the mildly ferro-magnetic alloy Monel 400. Due to the rapid advances in permanent magnet technology similar probes have been upgraded to magnetically saturate, and hence inspect, the duplex stainless steel Sandvik 3RE60, which has saturation induction more than twice that of Monel 400. Prototypes of these probes have been tested in three ways: saturation capability, quality of typical eddy current data, and ability to eliminate permeability induced signals. Successful laboratory testing, potential applications, and limitations of these type probes are discussed

  9. Excitation spectrum of ferromagnetic xxz-chains

    International Nuclear Information System (INIS)

    Schneider, T.; Stoll, E.

    1983-01-01

    In the history of xxz-Heisenberg spin chains, understanding of the dynamic form factors (DFF) is much less advanced. In this paper the DFF of ferromagnetic xxz chains as a tool to probe and interpret excitation spectrum is reviewed. The Isingheisenberg chain, and the Planar-Heisenberg chain (where HF approximations become exact) are studied. The results provide instructive connections between spin systems, interacting fermions and bosons. Various new aspects--thermally induced bound state effects in terms of central peaks in DFF for Isinglike xxz chains; the possibility to observe bound states in S /SUB zz/ (q,w) accessible by neutron scattering techniques, in the planar system--are found

  10. Spin transport in ferromagnetically contacted carbon nanotubes

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, C.; Morgan, C.; Schneider, C.M. [Peter Gruenberg Institut, PGI-6, Forschungszentrum Juelich and JARA Juelich Aachen Research Alliance, 52425 Juelich (Germany)

    2011-11-15

    We present magnetoresistance (MR) measurements on carbon nanotubes (CNTs) with different ferromagnetic leads. A sample with permalloy (Ni{sub 80}Fe{sub 20}) contacts shows the expected tunneling-type MR effect. Measurements on devices with CoPd contacts show a larger change of resistance with magnetic field. However, only minor loops are observed, which is explained with domain wall pinning. This is supported by magnetic force microscopy (MFM) measurements, which reveal a complicated bubble and stripe domain pattern. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  11. Theory of electromagnetic wave propagation in ferromagnetic Rashba conductor

    Science.gov (United States)

    Shibata, Junya; Takeuchi, Akihito; Kohno, Hiroshi; Tatara, Gen

    2018-02-01

    We present a comprehensive study of various electromagnetic wave propagation phenomena in a ferromagnetic bulk Rashba conductor from the perspective of quantum mechanical transport. In this system, both the space inversion and time reversal symmetries are broken, as characterized by the Rashba field α and magnetization M, respectively. First, we present a general phenomenological analysis of electromagnetic wave propagation in media with broken space inversion and time reversal symmetries based on the dielectric tensor. The dependence of the dielectric tensor on the wave vector q and M is retained to first order. Then, we calculate the microscopic electromagnetic response of the current and spin of conduction electrons subjected to α and M, based on linear response theory and the Green's function method; the results are used to study the system optical properties. First, it is found that a large α enhances the anisotropic properties of the system and enlarges the frequency range in which the electromagnetic waves have hyperbolic dispersion surfaces and exhibit unusual propagations known as negative refraction and backward waves. Second, we consider the electromagnetic cross-correlation effects (direct and inverse Edelstein effects) on the wave propagation. These effects stem from the lack of space inversion symmetry and yield q-linear off-diagonal components in the dielectric tensor. This induces a Rashba-induced birefringence, in which the polarization vector rotates around the vector (α ×q ) . In the presence of M, which breaks time reversal symmetry, there arises an anomalous Hall effect and the dielectric tensor acquires off-diagonal components linear in M. For α ∥M , these components yield the Faraday effect for the Faraday configuration q ∥M and the Cotton-Mouton effect for the Voigt configuration ( q ⊥M ). When α and M are noncollinear, M- and q-induced optical phenomena are possible, which include nonreciprocal directional dichroism in the

  12. Moment Closure for the Stochastic Logistic Model

    National Research Council Canada - National Science Library

    Singh, Abhyudai; Hespanha, Joao P

    2006-01-01

    ..., which we refer to as the moment closure function. In this paper, a systematic procedure for constructing moment closure functions of arbitrary order is presented for the stochastic logistic model...

  13. Ferromagnetism and suppression of metallic clusters in Fe implanted ZnO -- a phenomenon related to defects?

    International Nuclear Information System (INIS)

    Arenholz, Elke; Zhou, S.; Potzger, K.; Talut, G.; Reuther, H.; Kuepper, K.; Grenzer, J.; Xu, Q.; Mucklich, A.; Helm, M.; Fassbender, J.; Arenholz, E.

    2008-01-01

    We investigated ZnO(0001) single crystals annealed in high vacuum with respect to their magnetic properties and cluster formation tendency after implant-doping with Fe. While metallic Fe cluster formation is suppressed, no evidence for the relevance of the Fe magnetic moment to the observed ferromagnetism was found. The latter along with the cluster suppression is discussed with respect to defects in the ZnO host matrix, since the crystalline quality of the substrates was lowered due to the preparation as observed by x-ray diffraction

  14. Ferromagnetism and suppression of metallic clusters in Fe implanted ZnO: a phenomenon related to defects?

    International Nuclear Information System (INIS)

    Zhou Shengqiang; Potzger, K; Talut, G; Reuther, H; Kuepper, K; Grenzer, J; Xu Qingyu; Muecklich, A; Helm, M; Fassbender, J; Arenholz, E

    2008-01-01

    We investigated ZnO(0 0 0 1) single crystals annealed in high vacuum with respect to their magnetic properties and cluster formation tendency after implant-doping with Fe. While metallic Fe cluster formation is suppressed, no evidence for the relevance of the Fe magnetic moment to the observed ferromagnetism was found. The latter along with the cluster suppression is discussed with respect to defects in the ZnO host matrix, since the crystalline quality of the substrates was lowered due to the preparation as observed by x-ray diffraction

  15. Hole-doping effects on the magnetic properties of the La4Ba2Cu2O10 ferromagnet

    International Nuclear Information System (INIS)

    Mizuno, F.; Masuda, H.; Hirabayashi, I.; Tanaka, S.; Mochiku, T.; Asano, H.; Izumi, F.

    1992-01-01

    Hole-doping effects by Ba substitution for La in La 4-x Ba 2+x Cu 2 O 10 (0 ≤ x ≤ 1) have been studied to explore the possibilities of its metal-insulator transition and superconductivity. We have not detected any symptoms for metal-insulator transition, but found certain evidence for the hole-doping effect. We observed the dilution effect of Cu 2+ spin by non-magnetic Cu 3+ on the ferromagnetic transition temperature and the reduction of effective magnetic moment. (orig.)

  16. SolNet

    DEFF Research Database (Denmark)

    Jordan, Ulrike; Vajen, Klaus; Bales, Chris

    2014-01-01

    -accompanying Master courses, placements of internships, and PhD scholarship projects. A new scholarship project, “SHINE”, was launched in autumn 2013 in the frame work of the Marie Curie program of the European Union (Initial Training Network, ITN). 13 PhD-scholarships on solar district heating, solar heat......SolNet, founded in 2006, is the first coordinated International PhD education program on Solar Thermal Engineering. The SolNet network is coordinated by the Institute of Thermal Engineering at Kassel University, Germany. The network offers PhD courses on solar heating and cooling, conference...... for industrial processes, as well as sorption stores and materials started in December 2013. Additionally, the project comprises a training program with five PhD courses and several workshops on solar thermal engineering that will be open also for other PhD students working in the field. The research projects...

  17. On the interpretation of the support moment

    NARCIS (Netherlands)

    Hof, AL

    2000-01-01

    It has been suggested by Winter (J. Biomech. 13 (1980) 923-927) that the 'support moment', the sum of the sagittal extension moments, shows less variability in walking than any of the joint moments separately. A simple model is put forward to explain this finding. It is proposed to reformulate the

  18. Turkey's net energy consumption

    International Nuclear Information System (INIS)

    Soezen, Adnan; Arcaklioglu, Erol; Oezkaymak, Mehmet

    2005-01-01

    The main goal of this study is to develop the equations for forecasting net energy consumption (NEC) using an artificial neural-network (ANN) technique in order to determine the future level of energy consumption in Turkey. In this study, two different models were used in order to train the neural network. In one of them, population, gross generation, installed capacity and years are used in the input layer of the network (Model 1). Other energy sources are used in input layer of network (Model 2). The net energy consumption is in the output layer for two models. Data from 1975 to 2003 are used for the training. Three years (1981, 1994 and 2003) are used only as test data to confirm this method. The statistical coefficients of multiple determinations (R 2 -value) for training data are equal to 0.99944 and 0.99913 for Models 1 and 2, respectively. Similarly, R 2 values for testing data are equal to 0.997386 and 0.999558 for Models 1 and 2, respectively. According to the results, the net energy consumption using the ANN technique has been predicted with acceptable accuracy. Apart from reducing the whole time required, with the ANN approach, it is possible to find solutions that make energy applications more viable and thus more attractive to potential users. It is also expected that this study will be helpful in developing highly applicable energy policies

  19. Nonlinear wave propagation through a ferromagnet with damping in ...

    Indian Academy of Sciences (India)

    magnetic waves in a ferromagnet can be reduced to an integro-differential equation. Keywords. Solitons; integro-differential equations; reductive perturbation method. PACS Nos 41.20 Jb; 05.45 Yv; 03.50 De; 78.20 Ls. 1. Introduction. The phenomenon of propagation of electromagnetic waves in ferromagnets are not only.

  20. Levitation properties of maglev systems using soft ferromagnets

    Science.gov (United States)

    Huang, Chen-Guang; Zhou, You-He

    2015-03-01

    Soft ferromagnets are widely used as flux-concentration materials in the design of guideways for superconducting magnetic levitation transport systems. In order to fully understand the influence of soft ferromagnets on the levitation performance, in this work we apply a numerical model based on the functional minimization method and the Bean’s critical state model to study the levitation properties of an infinitely long superconductor immersed in the magnetic field created by a guideway of different sets of infinitely long parallel permanent magnets with soft ferromagnets between them. The levitation force, guidance force, magnetic stiffness and magnetic pole density are calculated considering the coupling between the superconductor and soft ferromagnets. The results show that the levitation performance is closely associated with the permanent magnet configuration and with the location and dimension of the soft ferromagnets. Introducing the soft ferromagnet with a certain width in a few configurations always decreases the levitation force. However, for most configurations, the soft ferromagnets contribute to improve the levitation performance only when they have particular locations and dimensions in which the optimized location and thickness exist to increase the levitation force the most. Moreover, if the superconductor is laterally disturbed, the presence of soft ferromagnets can effectively improve the lateral stability for small lateral displacement and reduce the degradation of levitation force.

  1. Spin Heat Accumulation Induced by Tunneling from a Ferromagnet

    NARCIS (Netherlands)

    Vera-Marun, I.J.; Wees, B.J. van; Jansen, R.

    2014-01-01

    An electric current from a ferromagnet into a nonmagnetic material can induce a spin-dependent electron temperature. Here, it is shown that this spin heat accumulation, when created by tunneling from a ferromagnet, produces a non-negligible voltage signal that is comparable to that due to the

  2. Modelling the power losses in the ferromagnetic materials

    Directory of Open Access Journals (Sweden)

    Detka Kalina

    2017-07-01

    Full Text Available In this paper, the problem of describing power losses in ferromagnetic materials is considered. The limitations of Steinmetz formula are shown and a new analytical description of losses in a considered material is proposed. The correctness of the developed description is demonstrated experimentally by comparing the results of calculation with the catalogue characteristics for different ferromagnetic materials.

  3. Magnetic excitons in singlet-ground-state ferromagnets

    DEFF Research Database (Denmark)

    Birgeneau, R.J.; Als-Nielsen, Jens Aage; Bucher, E.

    1971-01-01

    The authors report measurements of the dispersion of singlet-triplet magnetic excitons as a function of temperature in the singlet-ground-state ferromagnets fcc Pr and Pr3Tl. Well-defined excitons are observed in both the ferromagnetic and paramagnetic regions, but with energies which are nearly...

  4. Giant proximity effect in ferromagnetic bilayers

    Science.gov (United States)

    Ramos, Silvia; Charlton, Tim; Quintanilla, Jorge; Suter, Andreas; Moodera, Jagadeesh; Prokscha, Thomas; Salman, Zaher; Forgan, Ted

    2013-03-01

    The proximity effect is a phenomenon where an ordered state leaks from a material into an adjacent one over some finite distance, ξ. For superconductors, this distance is ~ the coherence length. Nevertheless much longer-range, ``giant'' proximity effects have been observed in cuprate junctions. This surprising effect can be understood as a consequence of critical opalescence. Since this occurs near all second order phase transitions, giant proximity effects should be very general and, in particular, they should be present in magnetic systems. The ferromagnetic proximity effect has the advantage that its order parameter (magnetization) can be observed directly. We investigate the above phenomenon in Co/EuS bilayer films, where both materials undergo ferromagnetic transitions but at rather different temperatures (bulk TC of 1400K for Co and 16.6K for EuS). A dramatic increase in the range of the proximity effect is expected near the TC of EuS. We present the results of our measurements of the magnetization profiles as a function of temperature, carried out using the complementary techniques of low energy muon rotation and polarized neutron reflectivity. Work supported by EPSRC, STFC and ONR grant N00014-09-1-0177 and NSF grant DMR 0504158.

  5. Titanium nitride room-temperature ferromagnetic nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Morozov, Iu.G., E-mail: morozov@ism.ac.ru [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, 8 Academician Osipyan Street, Chernogolovka, Moscow Region, 142432 (Russian Federation); Belousova, O.V. [Institute of Structural Macrokinetics and Materials Science, Russian Academy of Sciences, 8 Academician Osipyan Street, Chernogolovka, Moscow Region, 142432 (Russian Federation); Belyakov, O.A. [Ogarev Mordovia State University, Saransk, 68 Bol' shevistskaya Street, 430005 (Russian Federation); Parkin, I.P., E-mail: i.p.parkin@ucl.ac.uk [Department of Chemistry, Materials Chemistry Research Centre, University College London, 20 Gordon Street, London, WC1H 0AJ (United Kingdom); Sathasivam, S. [Department of Chemistry, Materials Chemistry Research Centre, University College London, 20 Gordon Street, London, WC1H 0AJ (United Kingdom); Kuznetcov, M.V., E-mail: maxim1968@mail.ru [All-Russian Research Institute on Problems of Civil Defense and Emergencies of Emergency Control Ministry of Russia (EMERCOM), 7 Davidkovskaya Street, Moscow, 121352 (Russian Federation)

    2016-08-05

    Cubic and near-spherical TiN nanoparticles ranging in average size from 20 to 125 nm were prepared by levitation-jet aerosol synthesis through condensation of titanium vapor in an inert gas flow with gaseous nitrogen injection. The nanoparticles were characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), BET measurements, UV–Vis, FT-IR, Raman spectroscopy, XPS, and vibrating-sample magnetometry. Room-temperature ferromagnetism with maximum magnetization up to 2.5 emu/g was recorded for the nanoparticles. The results indicate that the observed ferromagnetic ordering was related to the defect Ti–N structures on the surface of nanoparticles. This suggestion is in good correlation with the measured spectroscopical data. - Highlights: • Levitation-jet aerosol synthesis of TiN nanoparticles (NPs). • SEM, XRD, BET, UV–vis, FT-IR, Raman, XPS and magnetic characterization of the NPs. • Correlation between optical and XPS measurements data and maximum magnetization of the NPs.

  6. Electric and Magnetic Dipole Moments

    CERN Document Server

    CERN. Geneva

    2005-01-01

    The stringent limit on the electric dipole moment of the neutron forced the issue on the strong CP-problem. The most elegant solution of which is the axion field proposed by Peccei and Quinn. The current limit on the QCD parameter theta coming from the limit on the neutron EDM is of order 10-10. I am going to describe the present status on the neutron EDM searches and further prospects on getting down to theta_qcd sensitivity of 10-13 with the new deuteron EDM in storage rings proposal. For completeness the current status and prospects of the muon g-2 experiment will also be given.

  7. The Muon Electric Dipole Moment

    OpenAIRE

    Barger, Vernon; Kao, Chung; Das, Ashok

    1997-01-01

    The electric dipole moment of the muon ($d_\\mu$) is evaluated in a two Higgs doublet model with a softly broken discrete symmetry. For $\\tan\\beta \\equiv |v_2|/|v_1| \\sim 1$, contributions from two loop diagrams involving the $t$ quark and the $W$ boson dominate; while for $\\tan\\beta \\gsim 10$, contributions from two loop diagrams involving the $b$ quark and the $\\tau$ lepton are dominant. For $8 \\gsim \\tan\\beta \\gsim 4$, significant cancellation occurs among the contributions from two loop di...

  8. Room-temperature ferromagnetism in cerium dioxide powders

    Energy Technology Data Exchange (ETDEWEB)

    Rakhmatullin, R. M., E-mail: rrakhmat@kpfu.ru; Pavlov, V. V.; Semashko, V. V.; Korableva, S. L. [Kazan Federal University, Institute of Physics (Russian Federation)

    2015-08-15

    Room-temperature ferromagnetism is detected in a CeO{sub 2} powder with a grain size of about 35 nm and a low (<0.1 at %) manganese and iron content. The ferromagnetism in a CeO{sub 2} sample with a submicron crystallite size and the same manganese and iron impurity content is lower than in the nanocrystalline sample by an order of magnitude. Apart from ferromagnetism, both samples exhibit EPR spectra of localized paramagnetic centers, the concentration of which is lower than 0.01 at %. A comparative analysis of these results shows that the F-center exchange (FCE) mechanism cannot cause ferromagnetism. This conclusion agrees with the charge-transfer ferromagnetism model proposed recently.

  9. Influence of kinematic cuts on the net charge distribution

    Energy Technology Data Exchange (ETDEWEB)

    Petersen, Hannah [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Institut für Theoretische Physik, Goethe Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany); GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstr. 1, 64291 Darmstadt (Germany); Oliinychenko, Dmytro [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Bogolyubov Institute for Theoretical Physics, Kiev 03680 (Ukraine); Steinheimer, Jan [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Bleicher, Marcus [Frankfurt Institute for Advanced Studies, Ruth-Moufang-Str. 1, 60438 Frankfurt am Main (Germany); Institut für Theoretische Physik, Goethe Universität, Max-von-Laue-Str. 1, 60438 Frankfurt am Main (Germany)

    2016-12-15

    The higher moments of the net charge distributions, e.g. the skewness and kurtosis, are studied within an infinite hadronic matter calculation in a transport approach. By dividing the box into several parts, the volume dependence of the fluctuations is investigated. After confirming that the initial distributions follow the expectations from a binomial distribution, the influence of quantum number conservation in this case the net charge in the system on the higher moments is evaluated. For this purpose, the composition of the hadron gas is adjusted and only pions and ρ mesons are simulated to investigate the charge conservation effect. In addition, the effect of imposing kinematic cuts in momentum space is analysed. The role of resonance excitations and decays on the higher moments can also be studied within this model. This work is highly relevant to understand the experimental measurements of higher moments obtained in the RHIC beam energy scan and their comparison to lattice results and other theoretical calculations assuming infinite matter.

  10. Magnetic and thermal behaviour of the amorphous ferromagnet Fe79B16Si5

    International Nuclear Information System (INIS)

    Shaisha, E.E.; Bahgat, A.A.

    1985-01-01

    Spin waves in the amorphous ferromagnet Fe 79 B 16 Si 5 are studied by Moessbauer effect spectroscopy. The magnetic hyperfine field (MHF) is measured at the Fe sites of such a ferromagnet, which exhibits a temperature dependence of the form, H(T)/H(0) = (1 - BT/sup 3/2/ - CT/sup 5/2/), indicative of spin wave excitations in amorphous ferromagnets. The T/sup 3/2/ behaviour and the distribution of the exchange interactions are studied in detail as a function of the MHF. The spin wave excitations constant B/sub 3/2/ = BT/sub C//sup 3/2/ = 0.3 +- 0.05 and C/sub 5/2/ = CT/sub C//sup 5/2/ = 0.3 +- 0.05,Are obtained by fitting the experimental data, and where T/sub C/ = 670 K. The results sh=ow that the contribution of C/sub 5/2/ is extremely effective above 124 K, while the ratio C/sub 5/2//C/sub 3/2/ = 1.0 indicates that the present magnetic interaction is of long range order character. On the other hand, fluctuations of the exchange interaction constant are found to decrease with increasing temperature. Some information regarding the directions of the magnetic moments are obtained during the study of the magnetic anisotropy course. The values of the Einstein and Debye temperatures as measured from the thermal shift results are theta/sub E/ = 250 K and theta/sub D/ = 350 K,And from the Moessbauer factor measurements theta/sub E/ = 165 K and theta/sub D/ = 285 K. (autho=r)

  11. Reconstruction of convex bodies from moments

    DEFF Research Database (Denmark)

    Hörrmann, Julia; Kousholt, Astrid

    We investigate how much information about a convex body can be retrieved from a finite number of its geometric moments. We give a sufficient condition for a convex body to be uniquely determined by a finite number of its geometric moments, and we show that among all convex bodies, those which......- rithm that approximates a convex body using a finite number of its Legendre moments. The consistency of the algorithm is established using the stabil- ity result for Legendre moments. When only noisy measurements of Legendre moments are available, the consistency of the algorithm is established under...

  12. Net one, net two: the primary care network income statement.

    Science.gov (United States)

    Halley, M D; Little, A W

    1999-10-01

    Although hospital-owned primary care practices have been unprofitable for most hospitals, some hospitals are achieving competitive advantage and sustainable practice operations. A key to the success of some has been a net income reporting tool that separates practice operating expenses from the costs of creating and operating a network of practices to help healthcare organization managers, physicians, and staff to identify opportunities to improve the network's financial performance. This "Net One, Net Two" reporting allows operations leadership to be held accountable for Net One expenses and strategic leadership to be held accountable for Net Two expenses.

  13. Positron annihilation studies of vacancy-type defects and room temperature ferromagnetism in chemically synthesized Li-doped ZnO nanocrystals

    International Nuclear Information System (INIS)

    Ghosh, S.; Khan, Gobinda Gopal; Mandal, K.; Thapa, Samudrajit; Nambissan, P.M.G.

    2014-01-01

    Highlights: • Evidence of zinc vacancy-induced intrinsic ferromagnetism in Li-doped ZnO. • Modification of defects and properties through alkali metal substitution. • Study of defect-modification using positron annihilation spectroscopy. • New way to prepare ZnO-based magnetic semiconductor for spintronic applications. -- Abstract: In this article, we have investigated the effects of Li incorporation on the lattice defects and room-temperature d 0 ferromagnetic behaviour in ZnO nanocrystals by correlating X-ray photoelectron, photoluminescence and positron annihilation spectroscopic study in details. It is found that at low doping level ( 1+ is an effective substituent of Zn site, but it prefers to occupy the interstitial positions when Li-doping exceeds 7 at.% resulting in lattice expansion and increase of particle sizes. The pristine ZnO nanocrystals exhibit ferromagnetic behaviour which is further enhanced significantly after few percentage of Li-doping in ZnO. The magnitude of both saturation magnetizations (M S ) as well as the Curie temperature (T C ) are found to increase considerably up to Li concentration of 10 at.% and then started to decrease on further Li-doping. The gradual enhancement of Zn vacancy (V Zn ) defects in ZnO nanocrystals due to Li substitution as confirmed from photoluminescence and positron annihilation spectroscopy measurements might be responsible to induce paramagnetic moments within ZnO host. The ferromagnetic exchange interaction between the localised moments of V Zn defects can be mediated though the holes arising due to Li-substitutional (Li Zn ) acceptor defects within ZnO. Hence, Li doping in ZnO favours in stabilizing considerable V Zn defects and thus helps to sustain long-range high-T C ferromagnetism in ZnO which can be a promising material in future spintronics

  14. Positron annihilation studies of vacancy-type defects and room temperature ferromagnetism in chemically synthesized Li-doped ZnO nanocrystals

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, S., E-mail: sghoshphysics@gmail.com [S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Khan, Gobinda Gopal [Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, Technology Campus, Block JD2, Sector III, Salt Lake City, Kolkata 700098 (India); Mandal, K. [S.N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700098 (India); Thapa, Samudrajit; Nambissan, P.M.G. [Centre for Research in Nanoscience and Nanotechnology, University of Calcutta, Technology Campus, Block JD2, Sector III, Salt Lake City, Kolkata 700098 (India); Saha Institute of Nuclear Physics, Sector 1, Block AF, Bidhannagar, Kolkata 700064 (India)

    2014-03-25

    Highlights: • Evidence of zinc vacancy-induced intrinsic ferromagnetism in Li-doped ZnO. • Modification of defects and properties through alkali metal substitution. • Study of defect-modification using positron annihilation spectroscopy. • New way to prepare ZnO-based magnetic semiconductor for spintronic applications. -- Abstract: In this article, we have investigated the effects of Li incorporation on the lattice defects and room-temperature d{sup 0} ferromagnetic behaviour in ZnO nanocrystals by correlating X-ray photoelectron, photoluminescence and positron annihilation spectroscopic study in details. It is found that at low doping level (<7 at.%), Li{sup 1+} is an effective substituent of Zn site, but it prefers to occupy the interstitial positions when Li-doping exceeds 7 at.% resulting in lattice expansion and increase of particle sizes. The pristine ZnO nanocrystals exhibit ferromagnetic behaviour which is further enhanced significantly after few percentage of Li-doping in ZnO. The magnitude of both saturation magnetizations (M{sub S}) as well as the Curie temperature (T{sub C}) are found to increase considerably up to Li concentration of 10 at.% and then started to decrease on further Li-doping. The gradual enhancement of Zn vacancy (V{sub Zn}) defects in ZnO nanocrystals due to Li substitution as confirmed from photoluminescence and positron annihilation spectroscopy measurements might be responsible to induce paramagnetic moments within ZnO host. The ferromagnetic exchange interaction between the localised moments of V{sub Zn} defects can be mediated though the holes arising due to Li-substitutional (Li{sub Zn}) acceptor defects within ZnO. Hence, Li doping in ZnO favours in stabilizing considerable V{sub Zn} defects and thus helps to sustain long-range high-T{sub C} ferromagnetism in ZnO which can be a promising material in future spintronics.

  15. Above room temperature ferromagnetism in Si:Mn and TiO(2-delta)Co.

    Science.gov (United States)

    Granovsky, A; Orlov, A; Perov, N; Gan'shina, E; Semisalova, A; Balagurov, L; Kulemanov, I; Sapelkin, A; Rogalev, A; Smekhova, A

    2012-09-01

    We present recent experimental results on the structural, electrical, magnetic, and magneto-optical properties of Mn-implanted Si and Co-doped TiO(2-delta) magnetic oxides. Si wafers, both n- and p-type, with high and low resistivity, were used as the starting materials for implantation with Mn ions at the fluencies up to 5 x 10(16) cm(-2). The saturation magnetization was found to show the lack of any regular dependence on the Si conductivity type, type of impurity and the short post-implantation annealing. According to XMCD Mn impurity in Si does not bear any appreciable magnetic moment at room temperature. The obtained results indicate that above room temperature ferromagnetism in Mn-implanted Si originates not from Mn impurity but rather from structural defects in Si. The TiO(2-delta):Co thin films were deposited on LaAlO3 (001) substrates by magnetron sputtering in the argon-oxygen atmosphere at oxygen partial pressure of 2 x 10(-6)-2 x 10(-4) Torr. The obtained transverse Kerr effect spectra at the visible and XMCD spectra indicate on intrinsic room temperature ferromagnetism in TiO(2-delta):Co thin films at low (< 1%) volume fraction of Co.

  16. Excitonic Wigner crystal and high T sub c ferromagnetism in RB sub 6

    CERN Document Server

    Kasuya, T

    2000-01-01

    The mechanisms for the high T sub c ferromagnetism in La-doped divalent hexaborides DB sub 6 are studied in detail comparing with similar family materials, in particular with YbB sub 6 , EuB sub 6 and Ce monopnictides. It is shown that in DB sub 6 the light-electron-heavy-hole paired excitonic states form the Wigner crystal, or Wigner glass in actual materials, in which the conventional intersite electron exchange interactions similar to that in Ni dominate the pair singlet formation due to the intra pair mixing causing a ferromagnetic spin glass-like ordering of electron spins. In the La-doped system La sub x D sub 1 sub - sub x B sub 6 , the population of molecular La impurity states with giant moments increases as x approaches the optimal value x sub 0 approx 0.005 for high T sub c providing vacant states for the roton-like fluctuations, which cause the high T sub c at the boundary of the delocalization of electron carriers. Therefore, the critical La concentration for delocalization coincides with the opt...

  17. Ferromagnetic-phase transition in the spinel-type CuCr2Te4

    International Nuclear Information System (INIS)

    Suzuyama, Takeshi; Awaka, Junji; Yamamoto, Hiroki; Ebisu, Shuji; Ito, Masakazu; Suzuki, Takashi; Nakama, Takao; Yagasaki, Katsuma; Nagata, Shoichi

    2006-01-01

    Ferromagnetic-phase transition in spinel-type CuCr 2 Te 4 has been clearly observed. CuCr 2 Te 4 is a telluride-spinel with the lattice constant a=11.134A, which has been synthesized successfully. The heat capacity exhibits a sharp peak due to the ferromagnetic-phase transition with the Curie temperature T C =326K. This value of T C corresponds exactly to that of the negative peak of dM/dT in low field of 1.0Oe. The magnetic susceptibility shows the Curie-Weiss behavior between 380 and 650K with the effective magnetic moment μ eff =4.14μ B /Cr-ion and the Weiss constant θ=+357K. The low temperature magnetization indicates the spin-wave excitations, where the existence of first term of Bloch T 3/2 law and the next T 5/2 term are verified experimentally. This spin-wave excitation is detected up to approximately 250K which is a fairly high temperature

  18. Ferromagnetism in CVT grown tungsten diselenide single crystals with nickel doping

    Science.gov (United States)

    Habib, Muhammad; Muhammad, Zahir; Khan, Rashid; Wu, Chuanqiang; Rehman, Zia ur; Zhou, Yu; Liu, Hengjie; Song, Li

    2018-03-01

    Two dimensional (2D) single crystal layered transition materials have had extensive consideration owing to their interesting magnetic properties, originating from their lattices and strong spin-orbit coupling, which make them of vital importance for spintronic applications. Herein, we present synthesis of a highly crystalline tungsten diselenide layered single crystal grown by chemical vapor transport technique and doped with nickel (Ni) to tailor its magnetic properties. The pristine WSe2 single crystal and Ni-doped crystal were characterized and analyzed for magnetic properties using both experimental and computational aspects. It was found that the magnetic behavior of the 2D layered WSe2 crystal changed from diamagnetic to ferromagnetic after Ni-doping at all tested temperatures. Moreover, first principle density functional theory (DFT) calculations further confirmed the origin of room temperature ferromagnetism of Ni-doped WSe2, where the d-orbitals of the doped Ni atom promoted the spin moment and thus largely contributed to the magnetism change in the 2D layered material.

  19. Studying the superconductor-ferromagnet proximity effect with polarised neutron reflectometry

    Science.gov (United States)

    Satchell, Nathan; Cooper, Joshaniel; Kinane, Christy; Witt, James; Burnell, Gavin; Langridge, Sean

    At the interface between a superconductor (S) and ferromagnet (F), an inhomogeneity can convert singlet Cooper pairs into the (spin aligned) long ranged triplet component (LRTC). The manipulation of the LRTC forms the basis of the emerging field of super-spintronics. Several theoretical works predict modification to the local magnetic state inside the S layer with the inclusion of triplet Cooper pairs, however there are now several experimental observations which disagree on both the magnitude and direction of this induced moment (see for example and). Here we report on measurements of the proximity effect using polarised neutron reflectometry, a technique sensitive to changes in the total magnetisation of a S-F heterostructure. Our results suggest that a `smoking gun' direct signature of the LRTC is below the sensitivity of our technique, we are able to study the inverse effect namely a modification to the ferromagnetism by proximity to singlet superconductivity. These observations are supported by XMCD measurements showing changes to the Fe and Co below the S layer Tc.

  20. Enhanced heat rectification effect in a quantum dot connected to ferromagnetic leads

    Energy Technology Data Exchange (ETDEWEB)

    Chi, Feng, E-mail: chifeng@semi.ac.cn [School of Physical Science and Technology, Inner Mongolia University, Huhehaote 010023 (China); College of Engineering, Bohai University, Jinzhou 121013 (China); Sun, Lian-Liang [College of Science, North China University of Technology, Beijing 100041 (China); Zheng, Jun; Guo, Yu [College of Engineering, Bohai University, Jinzhou 121013 (China)

    2015-06-15

    We study theoretically the heat generation by electric current in an interacting single level quantum-dot connected to ferromagnetic leads. The heat is transferred between the dot and the lattice vibration of its host material (phonon reservoir). Particular attention is paid on the heat's rectification effect achieved by properly arranging the dot level and the bias voltage. We find that this effect is remarkably enhanced when the two leads' magnetic moments are in antiparallel configuration, i.e., the magnitude of the heat generation is reduced (amplified) in the negative (positive) bias regime as compared to the cases of parallel configuration and nonmagnetic leads. The rectification effect is even enhanced when one of the lead's spin polarization approaches to unit, during which the negative differential of the heat generation is weakened due to the change of the spin-dependent electron occupation numbers on the dot. The found results may be used for thermal transistor in the newly emerged research subject of phononics. - Highlights: • Heat flow between electrons and phonons is controlled by interaction between them. • A thermal diode or rectifier is proposed to work under electrical bias. • The heat rectification effect can be enhanced by the leads' ferromagnetism.

  1. Ferromagnetism of Pd(001) substrate induced by antiferromagnetic CoO

    Energy Technology Data Exchange (ETDEWEB)

    Saha, Srijan Kumar, E-mail: sksaha@mpi-halle.mpg.de; Stepanyuk, Valeri S.; Kirschner, Jürgen

    2014-11-14

    Our first-principles study has revealed unexpected spin polarization of the Pd(001) substrate in contact with antiferromagnetic CoO overlayers. We give an evidence that the ferromagnetism of Pd is caused by the zigzag positions of Co atoms with respect to the Pd interface, resulted from the lattice-mismatch driven structural relaxation. Because of the itinerant nature of its 4d electrons, we see that the ferromagnetic properties of Pd are highly sensitive to the local environment and can be enhanced further by increasing the thickness of CoO overlayer film or/and by applying an additional uniaxial pressure along c-axis exerted externally on the bottom layers of the Pd substrate. Our finding provides new functionality for the interfacial moments of the CoO/Pd system, which can be accessed experimentally, e.g., by the magneto-optical Kerr effect (MOKE) or/and by element-resolved X-ray magnetic circular dichroism (XMCD) measurement.

  2. Ferromagnetism of Pd(001) substrate induced by antiferromagnetic CoO

    Science.gov (United States)

    Saha, Srijan Kumar; Stepanyuk, Valeri S.; Kirschner, Jürgen

    2014-11-01

    Our first-principles study has revealed unexpected spin polarization of the Pd(001) substrate in contact with antiferromagnetic CoO overlayers. We give an evidence that the ferromagnetism of Pd is caused by the zigzag positions of Co atoms with respect to the Pd interface, resulted from the lattice-mismatch driven structural relaxation. Because of the itinerant nature of its 4d electrons, we see that the ferromagnetic properties of Pd are highly sensitive to the local environment and can be enhanced further by increasing the thickness of CoO overlayer film or/and by applying an additional uniaxial pressure along c-axis exerted externally on the bottom layers of the Pd substrate. Our finding provides new functionality for the interfacial moments of the CoO/Pd system, which can be accessed experimentally, e.g., by the magneto-optical Kerr effect (MOKE) or/and by element-resolved X-ray magnetic circular dichroism (XMCD) measurement.

  3. Unidirectional spin Hall magnetoresistance in topological insulator/ferromagnetic layer heterostructures

    Science.gov (United States)

    Kally, James; Lv, Yang; Zhang, Delin; Lee, Joon Sue; Samarth, Nitin; Wang, Jian-Ping; Department of Electrical; Computer Engineering, University of Minnesota, Minneapolis Collaboration; Department of Physics, Pennsylvania State University Collaboration

    The surface states of topological insulators offer a potentially very efficient way to generate spins and spin-orbit torques to magnetic moments in proximity. The switching by spin-orbit torque itself only requires two terminals so that a charge current can be applied. However, a third terminal with additional magnetic tunneling junction structure is needed to sense the magnetization state if such devices are used for memory and logic applications. The recent discovery of unidirectional spin Hall magnetoresistance in heavy metal/ferromagnetic and topological insulator/magnetically doped topological insulator systems offers an alternative way to sense magnetization while still keeping the number of terminals to minimal two. The unidirectional spin Hall magnetoresistance in topological insulator/strong ferromagnetic layer heterostructure system has yet not been reported. In this work, we report our experimental observations of such magnetoresistance. It is found to be present and comparable to the best result of the previous reported Ta/Co systems in terms of magnetoresistance per current density per total resistance.

  4. Unidirectional spin-Hall and Rashba-Edelstein magnetoresistance in topological insulator-ferromagnet layer heterostructures.

    Science.gov (United States)

    Lv, Yang; Kally, James; Zhang, Delin; Lee, Joon Sue; Jamali, Mahdi; Samarth, Nitin; Wang, Jian-Ping

    2018-01-09

    The large spin-orbit coupling in topological insulators results in helical spin-textured Dirac surface states that are attractive for topological spintronics. These states generate an efficient spin-orbit torque on proximal magnetic moments. However, memory or logic spin devices based upon such switching require a non-optimal three-terminal geometry, with two terminals for the writing current and one for reading the state of the device. An alternative two-terminal device geometry is now possible by exploiting the recent discovery of the unidirectional spin Hall magnetoresistance in heavy metal/ferromagnet bilayers and unidirectional magnetoresistance in magnetic topological insulators. Here, we report the observation of such unidirectional magnetoresistance in a technologically relevant device geometry that combines a topological insulator with a conventional ferromagnetic metal. Our devices show a figure of merit (magnetoresistance per current density per total resistance) that is more than twice as large as the highest reported values in all-metal Ta/Co bilayers.

  5. Multiple collinear magnetic arrangements in thin Mn films supported on Fe(001). Antiferromagnetic versus ferromagnetic behavior

    International Nuclear Information System (INIS)

    Martinez, E.; Vega, A.; Robles, R.; Vazquez de Parga, A.L.

    2005-01-01

    We present a theoretical study of the magnetic properties of thin Mn films of 6 and 7 monolayers supported on Fe(001). The ab-initio tight binding linear muffin tin orbital (TB-LMTO) method was used to investigate the competition between ferromagnetic (F) and antiferromagnetic (AF) couplings within the system. We found several collinear magnetic solutions that may coexist at room temperature. The most stable configurations are characterized by AF coupling between the surface and subsurface Mn layers together with F coupling between Mn and Fe at the interface. The ground state arrangements for the 6 and 7 Mn films display opposite sign of the surface magnetic moment relative to the Fe substrate. The implications of these results in the possible onset of non-collinear magnetism when a step is present at the interface are discussed in comparison with Cr/Fe systems where non-collinear magnetism has been recently reported

  6. Pressure dependence of the magnetic properties of various weakly ferromagnetic transition metal alloys

    International Nuclear Information System (INIS)

    Buis, N.

    1979-01-01

    A large number of experimental results are summarized obtained in an apparatus designed for the measurement of magnetization under high pressures (up to 5k bar gas pressure), at temperatures from 4.2K to room temperature and in magnetic fields up to 5.1 T. Two alloy systems studied were Zr (Fesub(1-x)Cosub(x)) 2 and Y(Fesub(x)Cosub(1-x)) 2 and no consistent picture could be deduced from the large pressure effects on the magnetization. Apparently, one cannot apply the model for weak itinerant ferromagnetism on Zr(Fesub(1-x)Cosub(x)) 2 or a simple giant moment model on Y(Fesub(x)Cosub(1-x)) 2 with small iron content, because the magnetic behaviour of both systems is too complicated. (C.F.)

  7. Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite

    KAUST Repository

    Lin, Aigu L.; Rodrigues, J. N B; Su, Chenliang; Milletari, M.; Loh, Kian Ping; Wu, Tao; Chen, Wei; Neto, A. H Castro; Adam, Shaffique; Wee, Andrew T S

    2015-01-01

    Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m2/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite. © 2015 Scientific Reports.

  8. Tunable room-temperature ferromagnet using an iron-oxide and graphene oxide nanocomposite

    KAUST Repository

    Lin, Aigu L.

    2015-06-23

    Magnetic materials have found wide application ranging from electronics and memories to medicine. Essential to these advances is the control of the magnetic order. To date, most room-temperature applications have a fixed magnetic moment whose orientation is manipulated for functionality. Here we demonstrate an iron-oxide and graphene oxide nanocomposite based device that acts as a tunable ferromagnet at room temperature. Not only can we tune its transition temperature in a wide range of temperatures around room temperature, but the magnetization can also be tuned from zero to 0.011 A m2/kg through an initialization process with two readily accessible knobs (magnetic field and electric current), after which the system retains its magnetic properties semi-permanently until the next initialization process. We construct a theoretical model to illustrate that this tunability originates from an indirect exchange interaction mediated by spin-imbalanced electrons inside the nanocomposite. © 2015 Scientific Reports.

  9. Experimental study of the spin density of metastable fcc ferromagnetic Fe-Cu alloys

    International Nuclear Information System (INIS)

    Bove, L. E.; Petrillo, C.; Sacchetti, F.; Mazzone, G.

    2000-01-01

    Magnetization density measurements on metastable Fe x Cu 1-x alloys at four compositions (x=20, 40, 50, and 60 at. %) and at 5 K temperature were carried out by means of polarized neutron diffraction. The samples were produced by high-energy ball milling and characterized by x-ray diffraction and fluorescence measurements. Additional bulk magnetization measurements were carried out on the two samples at high Fe concentration. Over the present concentration region, the Fe-Cu system is ferromagnetic and the four samples were found to be in the fcc phase. Fe-Cu is therefore a very suitable system to investigate the magnetic state of Fe in an fcc environment. Other than confirming that the Fe-Cu system is not a simple dilution alloy, the present results were compatible with a two-state model for fcc Fe--that is, two different coexisting electronic states associated with different magnetic moments and form factors

  10. Proof Nets for Lambek Calculus

    NARCIS (Netherlands)

    Roorda, Dirk

    1992-01-01

    The proof nets of linear logic are adapted to the non-commutative Lambek calculus. A different criterion for soundness of proof nets is given, which gives rise to new algorithms for proof search. The order sensitiveness of the Lambek calculus is reflected by the planarity condition on proof nets;

  11. Net metering: zero electricity bill

    International Nuclear Information System (INIS)

    Mangi, A.; Khan, Z.

    2011-01-01

    Worldwide move towards renewable energy sources, environmental concerns and decentralization of the power sector have made net metering an attractive option for power generation at small scale. This paper discusses the net metering, economical issues of renewable sources in Pakistan, technical aspects, installation suitability according to varying terrain, existing utility rules and formulation of legislation for net metering making it economically attractive. (author)

  12. The Net Advance of Physics

    Science.gov (United States)

    THE NET ADVANCE OF PHYSICS Review Articles and Tutorials in an Encyclopædic Format Established 1995 [Link to MIT] Computer support for The Net Advance of Physics is furnished by The Massachusetts Newest Additions SPECIAL FEATURES: Net Advance RETRO: Nineteenth Century Physics History of Science

  13. Spin-flip scattering effect on the current-induced spin torque in ferromagnet-insulator-ferromagnet tunnel junctions

    International Nuclear Information System (INIS)

    Zhu Zhengang; Su Gang; Jin Biao; Zheng Qingrong

    2003-01-01

    We have investigated the current-induced spin transfer torque of a ferromagnet-insulator-ferromagnet tunnel junction by taking the spin-flip scatterings into account. It is found that the spin-flip scattering can induce an additional spin torque, enhancing the maximum of the spin torque and giving rise to an angular shift compared to the case when the spin-flip scatterings are neglected. The effects of the molecular fields of the left and right ferromagnets on the spin torque are also studied. It is found that τ Rx /I e (τ Rx is the spin-transfer torque acting on the right ferromagnet and I e is the tunneling electrical current) does vary with the molecular fields. At two certain angles, τ Rx /I e is independent of the molecular field of the right ferromagnet, resulting in two crossing points in the curve of τ Rx /I e versus the relevant orientation for different molecular fields

  14. Horizontal ichthyoplankton tow-net system with unobstructed net opening

    Science.gov (United States)

    Nester, Robert T.

    1987-01-01

    The larval fish sampler described here consists of a modified bridle, frame, and net system with an obstruction-free net opening and is small enough for use on boats 10 m or less in length. The tow net features a square net frame attached to a 0.5-m-diameter cylinder-on-cone plankton net with a bridle designed to eliminate all obstructions forward of the net opening, significantly reducing currents and vibrations in the water directly preceding the net. This system was effective in collecting larvae representing more than 25 species of fish at sampling depths ranging from surface to 10 m and could easily be used at greater depths.

  15. Moment-to-moment dynamics of ADHD behaviour

    Directory of Open Access Journals (Sweden)

    Aase Heidi

    2005-08-01

    learning long behavioural sequences may ultimately lead to deficient development of verbally governed behaviour and self control. The study represents a new approach to analyzing the moment-to-moment dynamics of behaviour, and provides support for the theory that reinforcement processes are altered in ADHD.

  16. Spin-resolved x-ray photoemission studies of ferromagnetic metals

    International Nuclear Information System (INIS)

    Klebanoff, L.E.

    1996-01-01

    Recent spin-resolved x-ray photoelectron spectroscopy (SRXPS) studies of ferromagnetic metals are reviewed. SRXPS studies of metallic Fe, Co, Co 66 Fe 4 Ni 1 B 14 Si 15 , and Ni demonstrate that core-level photoemission, and the itinerant electron response to core-hole creation, are highly spin-dependent. The exchange splitting of the Fe 2p 3/2 level is found to be 0.48±0.05 eV. Lifetime broadening results for the Fe 2p 3/2 N↑ (majority spin) and N↓ (minority spin) components indicate conservation of spin in core-hole filling processes involving the valence band. SRXPS study of the Fe 2p 3/2 peak asymmetry α reveals a dependence of electron endash hole excitation on the spin of the core hole. Spin analysis of the Fe 3s XPS line shape shows it to be a three-component spectrum, rather than the two-component line shape assumed previously. A photon energy dependence of one of the Fe 3s components explains disagreement among previous Fe 3s XPS results. Comparisons of SRXPS from Co metal and Co 66 Fe 4 Ni 1 B 14 Si 15 directly demonstrate the effect of a reduced atomic magnetic moment on the spin dependence of core-level XPS. The behavior of lifetime broadenings for the N↑ and N↓ Co 2p 3/2 components show that the reduced Co magnetic moment found in the Co 66 Fe 4 Ni 1 B 14 Si 15 amorphous glass is due to the transfer of ↑-spin valence electron density to the ↓-spin valence band upon glass formation. SRXPS also allows investigation of spin-dependent core-hole screening processes and satellite production, as demonstrated in SRXPS studies of ferromagnetic Ni. Future directions of SRXPS are also explored. copyright 1996 American Vacuum Society

  17. Master Robotic Net

    Directory of Open Access Journals (Sweden)

    Vladimir Lipunov

    2010-01-01

    Full Text Available The main goal of the MASTER-Net project is to produce a unique fast sky survey with all sky observed over a single night down to a limiting magnitude of 19-20. Such a survey will make it possible to address a number of fundamental problems: search for dark energy via the discovery and photometry of supernovae (including SNIa, search for exoplanets, microlensing effects, discovery of minor bodies in the Solar System, and space-junk monitoring. All MASTER telescopes can be guided by alerts, and we plan to observe prompt optical emission from gamma-ray bursts synchronously in several filters and in several polarization planes.

  18. Preparation of Boron Nitride Nanoparticles with Oxygen Doping and a Study of Their Room-Temperature Ferromagnetism.

    Science.gov (United States)

    Lu, Qing; Zhao, Qi; Yang, Tianye; Zhai, Chengbo; Wang, Dongxue; Zhang, Mingzhe

    2018-04-18

    In this work, oxygen-doped boron nitride nanoparticles with room-temperature ferromagnetism have been synthesized by a new, facile, and efficient method. There are no metal magnetic impurities in the nanoparticles analyzed by X-ray photoelectron spectroscopy. The boron nitride nanoparticles exhibit a parabolic shape with increase in the reaction time. The saturation magnetization value reaches a maximum of 0.2975 emu g -1 at 300 K when the reaction time is 12 h, indicating that the Curie temperature ( T C ) is higher than 300 K. Combined with first-principles calculation, the coupling between B 2p orbital, N 2p orbital, and O 2p orbital in the conduction bands is the main origin of room-temperature ferromagnetism and also proves that the magnetic moment changes according the oxygen-doping content change. Compared with other room temperature ferromagnetic semiconductors, boron nitride nanoparticles have widely potential applications in spintronic devices because of high temperature oxidation resistance and excellent chemical stability.

  19. Limitations of shallow nets approximation.

    Science.gov (United States)

    Lin, Shao-Bo

    2017-10-01

    In this paper, we aim at analyzing the approximation abilities of shallow networks in reproducing kernel Hilbert spaces (RKHSs). We prove that there is a probability measure such that the achievable lower bound for approximating by shallow nets can be realized for all functions in balls of reproducing kernel Hilbert space with high probability, which is different with the classical minimax approximation error estimates. This result together with the existing approximation results for deep nets shows the limitations for shallow nets and provides a theoretical explanation on why deep nets perform better than shallow nets. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Shielding calculations for NET

    International Nuclear Information System (INIS)

    Verschuur, K.A.; Hogenbirk, A.

    1991-05-01

    In the European Fusion Technology Programme there is only a small activity on research and development for fusion neutronics. Never-the-less, looking further than blanket design now, as ECN is getting involved in design of radiation shields for the coils and biological shields, it becomes apparent that fusion neutronics as a whole still needs substantial development. Existing exact codes for calculation of complex geometries like MCNP and DORT/TORT are put over the limits of their numerical capabilities, whilst approximate codes for complex geometries like FURNACE and MERCURE4 are put over the limits of their modelling capabilities. The main objective of this study is just to find out how far we can get with existing codes in obtaining reliable values for the radiation levels inside and outside the cryostat/shield during operation and after shut-down. Starting with a 1D torus model for preliminary parametric studies, more dimensional approximation of the torus or parts of it including the main heterogeneities should follow. Regular contacts with the NET-Team are kept, to be aware of main changes in NET design that might affect our calculation models. Work on the contract started 1 July 1990. The technical description of the contract is given. (author). 14 refs.; 4 figs.; 1 tab

  1. Ab initio calculations of half-metallic ferromagnetism in Cr-doped MgSe and MgTe semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Noor, N.A. [Department of Physics, University of the Punjab, Quaid-e-Azam Campus, 54590 Lahore (Pakistan); Alay-e-Abbas, S.M. [Department of Physics, University of Sargodha, Sargodha 40100 (Pakistan); Department of Physics, GC University Faisalabad, Allama Iqbal Road, Faisalabad 38000 (Pakistan); Sohaib, M.U. [Lahore Development Authority, 54590 Lahore (Pakistan); Ghulam Abbas, S.M. [Department of Chemistry, University of Agriculture, Faisalabad 38040 (Pakistan); Shaukat, A., E-mail: schaukat@gmail.com [Department of Physics, University of Sargodha, Sargodha 40100 (Pakistan)

    2015-01-15

    The full-potential linear-augmented-plane-waves plus local-orbitals (FP-LAPW+lo) method has been employed for investigation of half-metallic ferromagnetism in Cr-doped ordered zinc-blende MgSe and MgTe semiconductors. Calculations of exchange and correlation (XC) effects have been carried out using generalized gradient approximation (GGA) and orbital independent modified Becke–Johnson potential coupled with local (spin) density approximation (mBJLDA). The thermodynamic stability of the compounds and their preferred magnetic orders have been analyzed in terms of the heat of formation and minimum total energy difference in ferromagnetic (FM) and anti-ferromagnetic (AFM) ordering, respectively. Calculated electronic properties reveal that the Cr-doping induces ferromagnetism in MgSe and MgTe which gives rise to a half-metallic (HM) gap at Fermi level (E{sub F}). Further, the electronic band structure is discussed in terms of s (p)–d exchange constants that are consistent with typical magneto-optical experiment and the behavior of charge spin densities is presented for understanding the bonding nature. Our results demonstrate that the higher effective potential for the spin-down case is responsible for p–d exchange splitting. Total magnetic moment (mainly due to Cr-d states) of these compounds is 4µ{sub B}. Importantly, the electronic properties and HM gap obtained using mBJLDA show remarkable improvement as compared to the results obtained using standard GGA functional. - Highlights: • Spin effect theoretical study on Cr-doped MgSe and MgTe is performed. • Half-metallic ferromagnetism in Cr{sub x}Mg{sub 1−x}Se and Cr{sub x}Mg{sub 1−x}Te is established. • Results of WC-GGA and mBJLDA are compared for performance. • HM gaps for Cr{sub x}Mg{sub 1−x}Se and Cr{sub x}Mg{sub 1−x}Te show nonlinear variation with x. • Important values of exchange splitting/constants and moments are reported.

  2. Radical-lanthanide ferromagnetic interaction in a T bIII bis-phthalocyaninato complex

    Science.gov (United States)

    Komijani, Dorsa; Ghirri, Alberto; Bonizzoni, Claudio; Klyatskaya, Svetlana; Moreno-Pineda, Eufemio; Ruben, Mario; Soncini, Alessandro; Affronte, Marco; Hill, Stephen

    2018-02-01

    Recent studies have highlighted the importance of organic ligands in the field of molecular spintronics, via which delocalized electron-spin density can mediate magnetic coupling to otherwise localized 4 f moments of lanthanide ions, which show tremendous potential for single-molecule device applications. To this end, high-field/high-frequency electron paramagnetic resonance (EPR) spectroscopy is employed to study a neutral terbium bis-phthalocyaninato metalorganic complex, [TbPc2 ] 0, with the aim of understanding the magnetic interaction between the Ising-like moment of the lanthanide ion and the unpaired spin density on the coordinating organic radical ligand. The measurements were performed on a previously unknown [TbPc2 ] 0 structural phase crystallizing in the Pnma space group. EPR measurements on powder samples of [TbPc2 ] 0 reveal an anisotropic spectrum, which is attributed to the spin-1/2 radical coupled weakly to the EPR-silent T bIII ion. Extensive double-axis rotation studies on a single crystal reveal two independent spin-1/2 signals with differently oriented (albeit identical) uniaxial g -tensors, in complete agreement with x-ray structural studies that indicate two molecular orientations within the unit cell. The easy-axis nature of the radical EPR spectra thus reflects the coupling to the Ising-like T bIII moment. This is corroborated by studies of the isostructural [YPc2 ] 0 analog (where Y is nonmagnetic yttrium), which gives a completely isotropic radical EPR signal. The experimental results for the terbium complex are well explained on the basis of an effective model that introduces a weak ferromagnetic Heisenberg coupling between an isotropic spin-1/2 and an anisotropic spin-orbital moment, J =6 , that mimics the known, strong easy-axis Tb ⋯P c2 crystal-field interaction.

  3. Perfect GMR effect in gapped graphene-based ferromagnetic normal ferromagnetic junctions

    Institute of Scientific and Technical Information of China (English)

    Hossein Karbaschi; Gholam Reza Rashedi

    2015-01-01

    We investigate the quantum transport property in gapped graphene-based ferromagnetic/normal/ferromagnetic (FG/NG/FG) junctions by using the Dirac–Bogoliubov–de Gennes equation. The graphene is fabricated on SiC and BN substrates separately, so carriers in FG/NG/FG structures are considered as massive relativistic particles. Transmission prob-ability, charge, and spin conductances are studied as a function of exchange energy of ferromagnets (h), size of graphene gap, and thickness of normal graphene region (L) respectively. Using the experimental values of Fermi energy in the normal graphene part (EFN∼400 meV) and energy gap in graphene (260 meV for SiC and 50 meV for BN substrate), it is shown that this structure can be used for both spin-up and spin-down polarized current. The latter case has different behavior of gapped FG/NG/FG from that of gapless FG/NG/FG structures. Also perfect charge giant magnetoresistance is observed in a range of EFN−mv2F

  4. ''Soft'' Anharmonic Vortex Glass in Ferromagnetic Superconductors

    International Nuclear Information System (INIS)

    Radzihovsky, Leo; Ettouhami, A. M.; Saunders, Karl; Toner, John

    2001-01-01

    Ferromagnetic order in superconductors can induce a spontaneous vortex (SV) state. For external field H=0 , rotational symmetry guarantees a vanishing tilt modulus of the SV solid, leading to drastically different behavior than that of a conventional, external-field-induced vortex solid. We show that quenched disorder and anharmoinc effects lead to elastic moduli that are wave-vector dependent out to arbitrarily long length scales, and non-Hookean elasticity. The latter implies that for weak external fields H , the magnetic induction scales universally like B(H)∼B(0)+cH α , with α∼0.72 . For weak disorder, we predict the SV solid is a topologically ordered glass, in the ''columnar elastic glass'' universality class

  5. Room temperature ferromagnetic gadolinium silicide nanoparticles

    Science.gov (United States)

    Hadimani, Magundappa Ravi L.; Gupta, Shalabh; Harstad, Shane; Pecharsky, Vitalij; Jiles, David C.

    2018-03-06

    A particle usable as T1 and T2 contrast agents is provided. The particle is a gadolinium silicide (Gd5Si4) particle that is ferromagnetic at temperatures up to 290 K and is less than 2 .mu.m in diameter. An MRI contrast agent that includes a plurality of gadolinium silicide (Gd.sub.5Si.sub.4) particles that are less than 1 .mu.m in diameter is also provided. A method for creating gadolinium silicide (Gd5Si4) particles is also provided. The method includes the steps of providing a Gd5Si4 bulk alloy; grinding the Gd5Si4 bulk alloy into a powder; and milling the Gd5Si4 bulk alloy powder for a time of approximately 20 minutes or less.

  6. Muon spin relaxation in ferromagnets. Pt. 1

    International Nuclear Information System (INIS)

    Lovesey, S.W.; Karlsson, E.B.

    1991-04-01

    Expressions for the dipolar and hyperfine contributions to the relaxation rate of muons implanted in a ferromagnet are presented and analysed using the Heisenberg model of spin-waves including dipolar and Zeeman energies. Calculations for EuO indicate that relaxation is likely to be dominated by the hyperfine mechanism, even if the ratio of the hyperfine and dipolar coupling constants is small. The hyperfine mechanism is sensitive to the dipolar energy of the atomic spins, whereas the dipolar mechanisms depend essentially on the exchange energy. For both mechanisms there is an almost quadratic dependence on temperature, throughout much of the ordered magnetic phase, which reflects two-spin-wave difference events from the Raman-type relaxation processes. (author)

  7. Ferromagnetic rollers in a harmonic confinement

    Science.gov (United States)

    Kaiser, Andreas; Snezhko, Alexey; Aranson, Igor S.

    We present the emergence of flocking and global rotation in a system of rolling ferromagnetic microparticles energized by a vertical alternating magnetic field confined in a harmonic potential. By combing experiments and discrete particle simulations, we have identified primary physical mechanisms leading to the emergence of large-scale collective motion: spontaneous symmetry breaking of the clock / counterclockwise particle rotation, collisional alignment of particle velocities, and random particle re-orientations due to shape imperfections. We also emphasize a subtle role of rotational noise: While the low-frequency flocking appears to be noise-insensitive, the reentrant flocking happens to be noise-activated. Moreover, we uncover a new relation between collective motion and synchronisation.

  8. Quantum stability for the Heisenberg ferromagnet

    International Nuclear Information System (INIS)

    Bargheer, Till; Beisert, Niklas; Gromov, Nikolay

    2008-01-01

    Highly spinning classical strings on RxS 3 are described by the Landau-Lifshitz model or equivalently by the Heisenberg ferromagnet in the thermodynamic limit. The spectrum of this model can be given in terms of spectral curves. However, it is a priori not clear whether any given admissible spectral curve can actually be realized as a solution to the discrete Bethe equations, a property which can be referred to as stability. In order to study the issue of stability, we find and explore the general two-cut solution or elliptic curve. It turns out that the moduli space of this elliptic curve shows a surprisingly rich structure. We present the various cases with illustrations and thus gain some insight into the features of multi-cut solutions. It appears that all admissible spectral curves are indeed stable if the branch cuts are positioned in a suitable, non-trivial fashion.

  9. Critical behavior of ferromagnetic Ising thin films

    International Nuclear Information System (INIS)

    Cossio, P.; Mazo-Zuluaga, J.; Restrepo, J.

    2006-01-01

    In the present work, we study the magnetic properties and critical behavior of simple cubic ferromagnetic thin films. We simulate LxLxd films with semifree boundary conditions on the basis of the Monte Carlo method and the Ising model with nearest neighbor interactions. A Metropolis dynamics was implemented to carry out the energy minimization process. For different film thickness, in the nanometer range, we compute the temperature dependence of the magnetization, the magnetic susceptibility and the fourth order Binder's cumulant. Bulk and surface contributions of these quantities are computed in a differentiated fashion. Additionally, according to finite size scaling theory, we estimate the critical exponents for the correlation length, magnetic susceptibility, and magnetization. Results reveal a strong dependence of critical temperature and critical exponents on the film thickness. The obtained critical exponents are finally compared to those reported in literature for thin films

  10. Surface effects in the Potts ferromagnet

    International Nuclear Information System (INIS)

    Tsallis, C.; Sarmento, E.F.

    1984-01-01

    Within a real space renormalisation group framework, the phase diagram of a semi-infinite cubic-lattice q-state Potts ferromagnet is studied, in which the free surface coupling constant J sub(S) = (1+Δ)J sub(B) might be different from the bulk one J sub(B). The starting value Δ sub(c) (q) is calculated above which surface order is possible even if bulk order is absent. Our results can be alternatively seen as approximate for the simple cubic lattice (as a matter of fact, the Ising value Δ sub(c) (2) obtained approaches the series result better than any other theory known consequently Δ sub(c) (q) is expected to be quite satisfactory even for q not= 2) or as exact for a well defined diamond-like hierarchical lattice. In the q →0 limit, Δ sub(c) diverges as 1/√q. (Author) [pt

  11. Heat exchanges in a quenched ferromagnet

    Energy Technology Data Exchange (ETDEWEB)

    Corberi, Federico; Zannetti, Marco [Dipartimento di Fisica ' E.R. Caianiello' , and CNISM, Unita di Salerno, Universita di Salerno, via Ponte don Melillo, I-84084 Fisciano, SA (Italy); Gonnella, Giuseppe; Piscitelli, Antonio [Dipartimento di Fisica, Universita di Bari and INFN, Sezione di Bari, via Amendola 173, I-70126 Bari (Italy)

    2013-02-01

    The off-equilibrium probability distribution of the heat exchanged by a ferromagnet in a time interval after a quench below the critical point is calculated analytically in the large-N limit. The distribution is characterized by a singular threshold Q{sub C} < 0, below which a macroscopic fraction of heat is released by the k = 0 Fourier component of the order parameter. The mathematical structure producing this phenomenon is the same responsible for the order parameter condensation in the equilibrium low temperature phase. The heat exchanged by the individual Fourier modes follows a non-trivial pattern, with the unstable modes at small wave vectors warming up the modes around a characteristic finite wave vector k{sub M}. Two internal temperatures, associated with the k = 0 and k = k{sub M} modes, rule the heat currents through a fluctuation relation similar to the one for stationary systems in contact with two thermal reservoirs. (fast track communication)

  12. The Critical Moment of Transition

    DEFF Research Database (Denmark)

    Svalgaard, Lotte

    2018-01-01

    By providing a holding environment to acknowledge sensitivities and address emotions, leadership programmes prove to be powerful spaces for increasing self- and social awareness. However, the challenge is for one to maintain the newly gained self- and social awareness after leaving the holding...... – within the context of an international MBA program – of MBA students applying their knowledge from a Leadership Stream in an International Consultancy Project. This paper contributes to the theory and practice of management learning by providing lenses to understand subjective experiences of critical...... moments of transition, developing the notion of “mindful avoidance,” and pointing out a major and neglected potential space in the design of management education....

  13. Neutron depolarization study of static and dynamic magnetic properties of ferromagnets

    International Nuclear Information System (INIS)

    Stuesser, N.

    1986-01-01

    In this thesis neutron depolarization experiments are performed on amorphous and crystalline ferromagnetic materials. The subjects studied are concerned with 'domain structure in magnetically weak uniaxial amorphous ferromagnetic ribbons', 'static critical behaviour at the ferromagnetic-paramagnetic phase transition', 'small magnetic anisotropy in nickel near T c ', and 'magnetization reversal in conducting ferromagnets'. 87 refs.; 37 figs.; 3 tabs

  14. Single-magnon tunneling through a ferromagnetic nanochain

    International Nuclear Information System (INIS)

    Petrov, E.G.; Ostrovsky, V.

    2010-01-01

    Magnon transmission between ferromagnetic contacts coupled by a linear ferromagnetic chain is studied at the condition when the chain exhibits itself as a tunnel magnon transmitter. It is shown that dependently on magnon energy at the chain, a distant intercontact magnon transmission occurs either in resonant or off-resonant tunneling regime. In the first case, a transmission function depends weakly on the number of chain sites whereas at off-resonant regime the same function manifests an exponential drop with the chain length. Change of direction of external magnetic field in one of ferromagnetic contacts blocks a tunnel transmission of magnon.

  15. Ferromagnetic properties of Mn-doped AlN

    International Nuclear Information System (INIS)

    Li, H.; Bao, H.Q.; Song, B.; Wang, W.J.; Chen, X.L.; He, L.J.; Yuan, W.X.

    2008-01-01

    Mn-doped AlN polycrystalline powders with a wurtzite structure were synthesized by solid-state reactions. A red-orange band at 600 nm, due to Mn 3+ incorporated into the AlN lattice, is observed in the photoluminescence (PL) spectrum at room temperature (RT). Magnetic measurements show the samples possess hysteresis loops up to 300 K, indicating that the obtained powders are ferromagnetic at around RT. The Mn concentration-induced RT ferromagnetism is less than 1 at%. Our results confirm that the RT ferromagnetism can be realized in Mn-doped AlN

  16. Flux penetration in a ferromagnetic/superconducting bilayer

    Energy Technology Data Exchange (ETDEWEB)

    Adamus, Z.; Cieplak, M.Z.; Abal' Oshev, A. [Polish Acad Sci, Inst Phys, PL-02668 Warsaw, (Poland); Konczykowski, M. [CEA/DSM/DRECAM, Laboratoire des Solides Irradies, F-91191 Gif Sur Yvette, (France); Konczykowski, M. [Ecole Polytech, CNRS - UMR 7642, F-91128 Palaiseau, (France); Cheng, X.M.; Zhu, L.Y.; Chien, C.L. [Johns Hopkins Univ, Dept Phys and Astron, Baltimore, MD 21218 (United States)

    2007-07-01

    An array of miniature Hall sensors is used to study the magnetic flux penetration in a ferromagnetic/superconducting bilayer consisting of Nb as a superconducting layer and Co/Pt multilayer with perpendicular magnetic anisotropy as a ferromagnetic layer, separated by an amorphous Si layer to avoid the proximity effect. It is found that the magnetic domains in the ferromagnetic layer create a large edge barrier in the superconducting layer which delays flux penetration. The smooth flux profiles observed in the absence of magnetic pinning change into terraced profiles in the presence of domains. (authors)

  17. Ni substitution effect on magnetic and transport properties in metallic ferromagnet Co3Sn2S2

    Science.gov (United States)

    Kubodera, Takashi; Okabe, Hirotaka; Kamihara, Yoichi; Matoba, Masanori

    2006-05-01

    We investigated the magnetic and transport properties of polycrystalline (Co1-xNix)3Sn2S2(0⩽x⩽1) to ascertain the magnetism of the new metallic ferromagnet Co3Sn2S2. In Co3Sn2S2 magnetization does not saturate up to 5.5 T at 10 K, and the estimated saturation moment ( ps) is small ( ≅0.2μB per Co atom). In ( Co1-xNix)3Sn2S2, the electrical resistivity shows metallic behavior without a hump but has a kink at TC. The TC and magnetic susceptibility gradually decrease with increasing x, and there is no antiferromagnetic phase throughout the full range of composition. These results indicate that Co3Sn2S2 is a weak itinerant ferromagnet; while, the same order of the Rhodes-Wohlfarth pc/ps value as CoS2 suggests the existence of a localized moment.

  18. The equivalency between logic Petri workflow nets and workflow nets.

    Science.gov (United States)

    Wang, Jing; Yu, ShuXia; Du, YuYue

    2015-01-01

    Logic Petri nets (LPNs) can describe and analyze batch processing functions and passing value indeterminacy in cooperative systems. Logic Petri workflow nets (LPWNs) are proposed based on LPNs in this paper. Process mining is regarded as an important bridge between modeling and analysis of data mining and business process. Workflow nets (WF-nets) are the extension to Petri nets (PNs), and have successfully been used to process mining. Some shortcomings cannot be avoided in process mining, such as duplicate tasks, invisible tasks, and the noise of logs. The online shop in electronic commerce in this paper is modeled to prove the equivalence between LPWNs and WF-nets, and advantages of LPWNs are presented.

  19. The Equivalency between Logic Petri Workflow Nets and Workflow Nets

    Science.gov (United States)

    Wang, Jing; Yu, ShuXia; Du, YuYue

    2015-01-01

    Logic Petri nets (LPNs) can describe and analyze batch processing functions and passing value indeterminacy in cooperative systems. Logic Petri workflow nets (LPWNs) are proposed based on LPNs in this paper. Process mining is regarded as an important bridge between modeling and analysis of data mining and business process. Workflow nets (WF-nets) are the extension to Petri nets (PNs), and have successfully been used to process mining. Some shortcomings cannot be avoided in process mining, such as duplicate tasks, invisible tasks, and the noise of logs. The online shop in electronic commerce in this paper is modeled to prove the equivalence between LPWNs and WF-nets, and advantages of LPWNs are presented. PMID:25821845

  20. Effects of Rashba and Dresselhaus spin-orbit couplings on itinerant ferromagnetism

    Science.gov (United States)

    Liu, Mengnan; Xu, Liping; Wan, Yong; Yan, Xu

    2018-02-01

    Based on Stoner model for itinerant ferromagnet, effects of spin-orbit coupling (SOC) on ferromagnetism were investigated at zero temperature. It was found that SOC will enhance the critical ferromagnetic exchange interaction for spontaneous magnetization, and then suppress ferromagnetism. In case of the coexistence of Rashba and Dresselhaus SOCs, the mixture of the two spin-orbit couplings showed stronger suppressed effect on ferromagnetism than only one kind of SOC alone. When the two SOCs mixed with equal magnitude, ferromagnetism in itinerant ferromagnet was suppressed to minimum.

  1. Art/Net/Work

    DEFF Research Database (Denmark)

    Andersen, Christian Ulrik; Lindstrøm, Hanne

    2006-01-01

    The seminar Art|Net|Work deals with two important changes in our culture. On one side, the network has become essential in the latest technological development. The Internet has entered a new phase, Web 2.0, including the occurrence of as ‘Wiki’s’, ‘Peer-2-Peer’ distribution, user controlled...... on the ‘network’ itself as a phenomenon and are often using technological networks as a mean of production and distribution. This changes the artistic practice and the distribution channels of art works – and the traditional notions of ‘work’, ‘origin’ and ‘rights’ are increasingly perceived as limiting...... the praxis of the artist. We see different kinds of interventions and activism (including ‘hacktivism’) using the network as a way of questioning the invisible rules that govern public and semi-public spaces. Who ‘owns’ them? What kind of social relationships do they generate? On what principle...

  2. Net4Care

    DEFF Research Database (Denmark)

    Christensen, Henrik Bærbak; Hansen, Klaus Marius

    2012-01-01

    , health centers are getting larger and more distributed, and the number of healthcare professionals does not follow the trend in chronic diseases. All of this leads to a need for telemedical and mobile health applications. In a Danish context, these applications are often developed through local...... (innovative) initiatives with little regards for national and global (standardization) initiatives. A reason for this discrepancy is that the software architecture for national (and global) systems and standards are hard to understand, hard to develop systems based on, and hard to deploy. To counter this, we...... propose a software ecosystem approach for telemedicine applications, providing a framework, Net4Care, encapsulating national/global design decisions with respect to standardization while allowing for local innovation. This paper presents an analysis of existing systems, of requirements for a software...

  3. Noncommutative QED and anomalous dipole moments

    International Nuclear Information System (INIS)

    Riad, I.F.; Sheikh-Jabbari, M.M.

    2000-09-01

    We study QED on noncommutative spaces, NCQED. In particular we present the detailed calculation for the noncommutative electron-photon vertex and show that the Ward identity is satisfied. We discuss that in the noncommutative case moving electron will show electric dipole effects. In addition, we work out the electric and magnetic dipole moments up to one loop level. For the magnetic moment we show that noncommutative electron has an intrinsic (spin independent) magnetic moment. (author)

  4. Electric dipole moment of diatomic molecules

    International Nuclear Information System (INIS)

    Rosato, A.

    1983-01-01

    The electric dipole moment of some diatomic molecules is calculated using the Variational Cellular Method. The results obtained for the molecules CO, HB, HF and LiH are compared with other calculations and with experimental data. It is shown that there is strong dependence of the electric dipole moment with respect to the geometry of the cells. It is discussed the possibility of fixing the geometry of the problem by giving the experimental value of the dipole moment. (Author) [pt

  5. Electric dipole moment of diatomic molecules

    International Nuclear Information System (INIS)

    Rosato, A.

    1983-01-01

    The electric dipole moment of some diatomic molecules is calculated using the Variational Cellular Method. The results obtained for the CO, HB, HF and LiH molecules are compared with other calculations and with experimental data. It is shown that there is strong dependence of the electric dipole moment with respect to the geometry of the cells. The possibility of fixing the geometry of the problem by giving the experimental value of the dipole moment is discussed. (Author) [pt

  6. Restrictions on the neutrino magnetic dipole moment

    International Nuclear Information System (INIS)

    Duncan, M.J.; Sankar, S.U.; Grifols, J.A.; Mendez, A.

    1987-01-01

    We examine mechanisms for producing neutrino magnetic moments from a wide class of particle theories which are extensions of the standard model. We show that it is difficult to naturally obtain a moment greater than ≅ 10 -2 electron Bohr magnetons. Thus models of phenomena requiring moments of order ≅ 10 -10 magnetons, such as those proposed as a resolution to the solar neutrino puzzle, are in conflict with current perceptions in particle physics. (orig.)

  7. W-boson electric dipole moment

    International Nuclear Information System (INIS)

    He, X.; McKellar, B.H.J.

    1990-01-01

    The W-boson electric dipole moment is calculated in the SU(3) C xSU(2) L xU(1) Y model with several Higgs-boson doublets. Using the constraint on the CP-violating parameters from the experimental upper bound of the neutron electric dipole moment, we find that the W-boson electric dipole moment is constrained to be less than 10 -4

  8. Magnetic field concentration using ferromagnetic material to propel a wireless power transfer based micro-robot

    Directory of Open Access Journals (Sweden)

    Dongwook Kim

    2018-05-01

    Full Text Available In this paper, we propose a novel coil structure, using a ferromagnetic material which concentrates the magnetic field, as the propulsion system of a wireless power transfer (WPT based micro-robot. This structure uses an incident magnetic field to induce current during wireless power transfer, to generate a Lorentz force. To prevent net cancelation of the Lorentz force in the load coil, ferrite films were applied to one side of the coil segment. The demonstrated simplicity and effectiveness of the proposed micro-robot showed its suitability for applications. Simulation and experimental results confirmed a velocity of 1.02 mm/s with 6 mW power transfer capacity for the 3 mm sized micro-robot.

  9. Spin-orbit driven ferromagnetic resonance: a nanoscale magnetic characterisation technique

    Czech Academy of Sciences Publication Activity Database

    Fang, D.; Kurebayashi, H.; Wunderlich, Joerg; Výborný, Karel; Zarbo, Liviu; Campion, R. P.; Casiraghi, A.; Gallagher, B. L.; Jungwirth, Tomáš; Ferguson, A.J.

    2011-01-01

    Roč. 6, č. 7 (2011), s. 413-417 ISSN 1748-3387 R&D Projects: GA AV ČR KAN400100652; GA MŠk LC510; GA AV ČR KJB100100802; GA MŠk(CZ) 7E08087 EU Projects: 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 Keywords : ferromagnetic resonance * spin-orbit coupling * nanomagnets Subject RIV: BM - Solid Matter Physics ; Magnet ism Impact factor: 27.270, year: 2011

  10. Magnetic field concentration using ferromagnetic material to propel a wireless power transfer based micro-robot

    Science.gov (United States)

    Kim, Dongwook; Park, Bumjin; Park, Jaehyoung; Park, Hyun Ho; Ahn, Seungyoung

    2018-05-01

    In this paper, we propose a novel coil structure, using a ferromagnetic material which concentrates the magnetic field, as the propulsion system of a wireless power transfer (WPT) based micro-robot. This structure uses an incident magnetic field to induce current during wireless power transfer, to generate a Lorentz force. To prevent net cancelation of the Lorentz force in the load coil, ferrite films were applied to one side of the coil segment. The demonstrated simplicity and effectiveness of the proposed micro-robot showed its suitability for applications. Simulation and experimental results confirmed a velocity of 1.02 mm/s with 6 mW power transfer capacity for the 3 mm sized micro-robot.

  11. How to introduce the magnetic dipole moment

    International Nuclear Information System (INIS)

    Bezerra, M; Kort-Kamp, W J M; Cougo-Pinto, M V; Farina, C

    2012-01-01

    We show how the concept of the magnetic dipole moment can be introduced in the same way as the concept of the electric dipole moment in introductory courses on electromagnetism. Considering a localized steady current distribution, we make a Taylor expansion directly in the Biot-Savart law to obtain, explicitly, the dominant contribution of the magnetic field at distant points, identifying the magnetic dipole moment of the distribution. We also present a simple but general demonstration of the torque exerted by a uniform magnetic field on a current loop of general form, not necessarily planar. For pedagogical reasons we start by reviewing briefly the concept of the electric dipole moment. (paper)

  12. Gross shell structure of moments of inertia

    International Nuclear Information System (INIS)

    Deleplanque, M.A.; Frauendorf, S.; Pashkevich, V.V.; Chu, S.Y.; Unzhakova, A.

    2002-01-01

    Average yrast moments of inertia at high spins, where the pairing correlations are expected to be largely absent, were found to deviate from the rigid-body values. This indicates that shell effects contribute to the moment of inertia. We discuss the gross dependence of moments of inertia and shell energies on the neutron number in terms of the semiclassical periodic orbit theory. We show that the ground-state shell energies, nuclear deformations and deviations from rigid-body moments of inertia are all due to the same periodic orbits

  13. Analysis of scaled-factorial-moment data

    International Nuclear Information System (INIS)

    Seibert, D.

    1990-01-01

    We discuss the two standard constructions used in the search for intermittency, the exclusive and inclusive scaled factorial moments. We propose the use of a new scaled factorial moment that reduces to the exclusive moment in the appropriate limit and is free of undesirable multiplicity correlations that are contained in the inclusive moment. We show that there are some similarities among most of the models that have been proposed to explain factorial-moment data, and that these similarities can be used to increase the efficiency of testing these models. We begin by calculating factorial moments from a simple independent-cluster model that assumes only approximate boost invariance of the cluster rapidity distribution and an approximate relation among the moments of the cluster multiplicity distribution. We find two scaling laws that are essentially model independent. The first scaling law relates the moments to each other with a simple formula, indicating that the different factorial moments are not independent. The second scaling law relates samples with different rapidity densities. We find evidence for much larger clusters in heavy-ion data than in light-ion data, indicating possible spatial intermittency in the heavy-ion events

  14. In-situ XMCD evaluation of ferromagnetic state at FeRh thin film surface induced by 1 keV Ar ion beam irradiation and annealing

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, T. [Research Organization for the 21st Century, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Aikoh, K. [Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan); Sakamaki, M.; Amemiya, K. [High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801 (Japan); Iwase, A. [Graduate School of Engineering, Osaka Prefecture University, Sakai, Osaka 599-8531 (Japan)

    2015-12-15

    Surface ferromagnetic state of FeRh thin films irradiated with 1 keV Ar ion-beam has been investigated by using soft X-ray Magnetic Circular Dichroism (XMCD). It was revealed that the Fe atoms of the samples were strongly spin-polarized after Ar ion-beam irradiation. Due to its small penetration depth, 1 keV Ar ion-beam irradiation can modify the magnetic state at subsurface of the samples. In accordance with the XMCD sum rule analysis, the main component of the irradiation induced ferromagnetism at the FeRh film surface was to be effective spin magnetic moment, and not to be orbital moment. We also confirmed that the surface ferromagnetic state could be produced by thermal annealing of the excessively ion irradiated paramagnetic subsurface of the FeRh thin films. This novel magnetic modification technique by using ion irradiation and subsequent annealing can be a potential tool to control the surface magnetic state of FeRh thin films.

  15. Ferromagnetic ordering in ThSi{sub 2} type CeAu{sub 0.28}Ge{sub 1.72}

    Energy Technology Data Exchange (ETDEWEB)

    Sebastian, C. Peter, E-mail: s-peter@northwestern.ed [Department of Chemistry, Northwestern University, 2145 N. Sheridan Road, Evanston, IL 60208-3113 (United States); Kanatzidis, Mercouri G., E-mail: m-kanatzidis@northwestern.ed [Department of Chemistry, Northwestern University, 2145 N. Sheridan Road, Evanston, IL 60208-3113 (United States)

    2010-04-15

    The compound CeAu{sub 0.28}Ge{sub 1.72} crystallizes in the ThSi{sub 2} structure type in the tetragonal space group I4{sub 1}/amd with lattice parameters a=b=4.2415(6) A c=14.640(3) A. CeAu{sub 0.28}Ge{sub 1.72} is a polar intermetallic compound having a three-dimensional Ge/Au polyanion sub-network filled with Ce atoms. The magnetic susceptibility data show Curie-Weiss law behavior above 50 K. The compound orders ferromagnetically at {approx}8 K with estimated magnetic moment of 2.48 mu{sub B}/Ce. The ferromagnetic ordering is confirmed by the heat capacity data which show a rise at {approx}8 K. The electronic specific heat coefficient (gamma) value obtained from the paramagnetic temperature range 15-25 K is {approx}124(5) mJ/ mol K{sup 2}. The entropy change due to the ferromagnetic transition is {approx}4.2 J/mol K which is appreciably reduced compared to the value of R ln(2) expected for a crystal-field-split doublet ground state and/or Kondo exchange interactions. - Graphical abstract: CeAu{sub 0.28}Ge{sub 1.72} crystallizes in the ThSi{sub 2} structure type in the tetragonal space group I4{sub 1}/amd and orders ferromagnetically at {approx}8 K.

  16. Invariant hip moment pattern while walking with a robotic hip exoskeleton.

    Science.gov (United States)

    Lewis, Cara L; Ferris, Daniel P

    2011-03-15

    Robotic lower limb exoskeletons hold significant potential for gait assistance and rehabilitation; however, we have a limited understanding of how people adapt to walking with robotic devices. The purpose of this study was to test the hypothesis that people reduce net muscle moments about their joints when robotic assistance is provided. This reduction in muscle moment results in a total joint moment (muscle plus exoskeleton) that is the same as the moment without the robotic assistance despite potential differences in joint angles. To test this hypothesis, eight healthy subjects trained with the robotic hip exoskeleton while walking on a force-measuring treadmill. The exoskeleton provided hip flexion assistance from approximately 33% to 53% of the gait cycle. We calculated the root mean squared difference (RMSD) between the average of data from the last 15 min of the powered condition and the unpowered condition. After completing three 30-min training sessions, the hip exoskeleton provided 27% of the total peak hip flexion moment during gait. Despite this substantial contribution from the exoskeleton, subjects walked with a total hip moment pattern (muscle plus exoskeleton) that was almost identical and more similar to the unpowered condition than the hip angle pattern (hip moment RMSD 0.027, angle RMSD 0.134, p<0.001). The angle and moment RMSD were not different for the knee and ankle joints. These findings support the concept that people adopt walking patterns with similar joint moment patterns despite differences in hip joint angles for a given walking speed. Copyright © 2011 Elsevier Ltd. All rights reserved.

  17. High-level Petri Nets

    DEFF Research Database (Denmark)

    various journals and collections. As a result, much of this knowledge is not readily available to people who may be interested in using high-level nets. Within the Petri net community this problem has been discussed many times, and as an outcome this book has been compiled. The book contains reprints...... of some of the most important papers on the application and theory of high-level Petri nets. In this way it makes the relevant literature more available. It is our hope that the book will be a useful source of information and that, e.g., it can be used in the organization of Petri net courses. To make......High-level Petri nets are now widely used in both theoretical analysis and practical modelling of concurrent systems. The main reason for the success of this class of net models is that they make it possible to obtain much more succinct and manageable descriptions than can be obtained by means...

  18. Tunneling time and Hartman effect in a ferromagnetic graphene superlattice

    Directory of Open Access Journals (Sweden)

    Farhad Sattari

    2012-03-01

    Full Text Available Using transfer-matrix and stationary phase methods, we study the tunneling time (group delay time in a ferromagnetic monolayer graphene superlattice. The system we peruse consists of a sequence of rectangular barriers and wells, which can be realized by putting a series of electronic gates on the top of ferromagnetic graphene. The magnetization in the two ferromagnetic layers is aligned parallel. We find out that the tunneling time for normal incident is independent of spin state of electron as well as the barrier height and electron Fermi energy while for the oblique incident angles the tunneling time depends on the spin state of electron and has an oscillatory behavior. Also the effect of barrier width on tunneling time is also investigated and shown that, for normal incident, the Hartman effect disappears in a ferromagnetic graphene superlattice but it appears for oblique incident angles when the x component of the electron wave vector in the barrier is imaginary.

  19. Possible mechanism for d0 ferromagnetism mediated by intrinsic defects

    KAUST Repository

    Zhang, Zhenkui

    2014-01-01

    We examine the effects of several intrinsic defects on the magnetic behavior of ZnS nanostructures using hybrid density functional theory to gain insights into d0 ferromagnetism. Previous studies have predicted that the magnetism is due to a coupling between partially filled defect states. By taking into account the electronic correlations, we find an additional splitting of the defect states in Zn vacancies and thus the possibility of gaining energy by preferential filling of hole states, establishing ferromagnetism between spin polarized S 3p holes. We demonstrate a crucial role of neutral S vacancies in promoting ferromagnetism between positively charged S vacancies. S dangling bonds on the nanoparticle surface also induce ferromagnetism. This journal is

  20. Comment on ``Ferromagnetic film on a superconducting substrate''

    Science.gov (United States)

    Sonin, E. B.

    2002-10-01

    A superconducting substrate is not able to shrink drastically domains in a ferromagnetic film, contrary to the prediction of Bulaevskii and Chudnovsky. This is shown on the basis of the exact solution for the stripe domain structure.

  1. Polarised neutron diffraction studies on weak ferromagnetism - a survey

    International Nuclear Information System (INIS)

    Radhakrishna, P.

    1982-10-01

    The physical basis of the phenomenon of weak ferromagnetism in certain antiferromagnetic insulators is briefly discussed. A survey of the contributions of polarised neutron diffraction towards the elucidation of different aspects of this field is presented

  2. Penetration of magnetic field in ferromagnetic transformer sheet

    Energy Technology Data Exchange (ETDEWEB)

    Sikora, R; Ziolkowski, M

    1981-01-12

    The paper deals with the penetration of magnetic field in a ferromagnetic transformer sheet. The flux-density distribution is computed using Galerkin's procedure. The different boundary conditions and the nonlinear B/H characteristic is taken into account.

  3. Possible mechanism for d0 ferromagnetism mediated by intrinsic defects

    KAUST Repository

    Zhang, Zhenkui; Schwingenschlö gl, Udo; Roqan, Iman S.

    2014-01-01

    We examine the effects of several intrinsic defects on the magnetic behavior of ZnS nanostructures using hybrid density functional theory to gain insights into d0 ferromagnetism. Previous studies have predicted that the magnetism is due to a

  4. Micromagnetic simulation of exchange coupled ferri-/ferromagnetic heterostructures

    Energy Technology Data Exchange (ETDEWEB)

    Oezelt, Harald, E-mail: harald.oezelt@fhstp.ac.at [Industrial Simulation, St. Pölten University of Applied Sciences, Matthias Corvinus-Straße 15, A-3100 St. Pölten (Austria); Kovacs, Alexander; Reichel, Franz; Fischbacher, Johann; Bance, Simon [Industrial Simulation, St. Pölten University of Applied Sciences, Matthias Corvinus-Straße 15, A-3100 St. Pölten (Austria); Gusenbauer, Markus [Center for Integrated Sensor Systems, Danube University Krems, Viktor Kaplan-Straße 2, A-2700 Wiener Neustadt (Austria); Schubert, Christian; Albrecht, Manfred [Institute of Physics, Chemnitz University of Technology, Reichenhainer Straße 70, D-09126 Chemnitz (Germany); Institute of Physics, University of Augsburg, Universitätsstraße 1, D-86159 Augsburg (Germany); Schrefl, Thomas [Industrial Simulation, St. Pölten University of Applied Sciences, Matthias Corvinus-Straße 15, A-3100 St. Pölten (Austria); Center for Integrated Sensor Systems, Danube University Krems, Viktor Kaplan-Straße 2, A-2700 Wiener Neustadt (Austria)

    2015-05-01

    Exchange coupled ferri-/ferromagnetic heterostructures are a possible material composition for future magnetic storage and sensor applications. In order to understand the driving mechanisms in the demagnetization process, we perform micromagnetic simulations by employing the Landau–Lifshitz–Gilbert equation. The magnetization reversal is dominated by pinning events within the amorphous ferrimagnetic layer and at the interface between the ferrimagnetic and the ferromagnetic layer. The shape of the computed magnetization reversal loop corresponds well with experimental data, if a spatial variation of the exchange coupling across the ferri-/ferromagnetic interface is assumed. - Highlights: • We present a model for exchange coupled ferri-/ferromagnetic heterostructures. • We incorporate the microstructural features of the amorphous ferrimagnet. • A distribution of interface exchange coupling is assumed to fit experimental data. • The reversal is dominated by pinning within the ferrimagnet and at the interface.

  5. Net neutrality and audiovisual services

    OpenAIRE

    van Eijk, N.; Nikoltchev, S.

    2011-01-01

    Net neutrality is high on the European agenda. New regulations for the communication sector provide a legal framework for net neutrality and need to be implemented on both a European and a national level. The key element is not just about blocking or slowing down traffic across communication networks: the control over the distribution of audiovisual services constitutes a vital part of the problem. In this contribution, the phenomenon of net neutrality is described first. Next, the European a...

  6. NetView technical research

    Science.gov (United States)

    1993-01-01

    This is the Final Technical Report for the NetView Technical Research task. This report is prepared in accordance with Contract Data Requirements List (CDRL) item A002. NetView assistance was provided and details are presented under the following headings: NetView Management Systems (NMS) project tasks; WBAFB IBM 3090; WPAFB AMDAHL; WPAFB IBM 3084; Hill AFB; McClellan AFB AMDAHL; McClellan AFB IBM 3090; and Warner-Robins AFB.

  7. Observation of strong ferromagnetism in the half-Heusler compound CoTiSb system

    Energy Technology Data Exchange (ETDEWEB)

    Sedeek, K., E-mail: KamiliaSedeek@yahoo.com; Hantour, H.; Makram, N.; Said, Sh. A.

    2016-06-01

    not obey the 18 valence electron/unit cell category of zero magnetic moment. Electronic structure calculations of the prepared stable multiphases CoTiSb is necessary to understand the origin of the detected strong half-metallic ferromagnetic behavior. - Highlights: • Synthesis by direct fusion yields stable multiphases CoTiSb half-Heusler alloy. • A mixture of well-ordered and distorted lattice planes characterizes the alloy. • De-mixing into multiphases altered the semiconducting CoTiSb to strong ferromagnet. • The alloy undergoes more than two ferromagnetic transitions with T{sub c} above 900 °K. • A proposed magnetic field diagram is given for the multiphases CoTiSb nano-system.

  8. The neutron electric dipole moment

    International Nuclear Information System (INIS)

    He, X.G.; McKellar, B.H.J.; Pakvasa, S.

    1989-01-01

    A systematic study was made of the electric dipole moment (EDM) of neutron D n in various models of CP violation. It was found that in the standard KM model with 3 families the neutron EDM is in the range 1.4x10 -33 ≤ D n ≤ 1.6x10 -31 ecm; that the two Higgs doublet model has approximately the same value of D n as the standard model; that D n in the Weinberg model is predicted to satisfy D n > 10 -25 ecm; that in a class of left-right symmetric models D n is of the order of 10 -26-11 ecm; that in supersymmetric models D n is of the order 10 -22 φ ecm with φ being the possible phase difference of the phases of gluino mass and the gluino-quark-smark mixing matrix and that the strong CP parameter θ is found to be θ -9 , using the present experimental limit that D n -25 ecm with 90% confidence. 65 refs., 10 figs

  9. Kant’s Machiavellian Moment

    Directory of Open Access Journals (Sweden)

    Jay Foster

    2015-11-01

    Full Text Available At least two recent collections of essays – Postmodernism and the Enlightenment (2001 and What’s Left of Enlightenment?: A Postmodern Question (2001 – have responded to postmodern critiques of Enlightenment by arguing that Enlightenment philosophes themselves embraced a number of post-modern themes. This essay situates Kant’s essay Was ist Aufklärung (1784 in the context of this recent literature about the appropriate characterization of modernity and the Enlightenment. Adopting an internalist reading of Kant’s Aufklärung essay, this paper observes that Kant is surprisingly ambivalent about who might be Enlightened and unspecific about when Enlightenment might be achieved. The paper argues that this is because Kant is concerned less with elucidating his concept of Enlightenment and more with characterizing a political condition that might provide the conditions for the possibility of Enlightenment. This paper calls this political condition modernity and it is achieved when civil order can be maintained alongside fractious and possibly insoluble public disagreement about matters of conscience, including the nature and possibility of Enlightenment. Thus, the audience for the Aufklärung essay is not the tax collector, soldier or clergyman, but rather the sovereign. Kant enjoins and advises the prince that discord and debate about matters of conscience need not entail any political unrest or upheaval. It is in this restricted (Pocockian sense that the Enlightenment essay is Kant’s Machiavellian moment.

  10. Stereo Correspondence Using Moment Invariants

    Science.gov (United States)

    Premaratne, Prashan; Safaei, Farzad

    Autonomous navigation is seen as a vital tool in harnessing the enormous potential of Unmanned Aerial Vehicles (UAV) and small robotic vehicles for both military and civilian use. Even though, laser based scanning solutions for Simultaneous Location And Mapping (SLAM) is considered as the most reliable for depth estimation, they are not feasible for use in UAV and land-based small vehicles due to their physical size and weight. Stereovision is considered as the best approach for any autonomous navigation solution as stereo rigs are considered to be lightweight and inexpensive. However, stereoscopy which estimates the depth information through pairs of stereo images can still be computationally expensive and unreliable. This is mainly due to some of the algorithms used in successful stereovision solutions require high computational requirements that cannot be met by small robotic vehicles. In our research, we implement a feature-based stereovision solution using moment invariants as a metric to find corresponding regions in image pairs that will reduce the computational complexity and improve the accuracy of the disparity measures that will be significant for the use in UAVs and in small robotic vehicles.

  11. Remote field eddy current testing of ferromagnetic tubes

    International Nuclear Information System (INIS)

    David, B.

    1990-01-01

    In order to test ferromagnetic tubes using internal probes, Intercontrole and the CEA have carried out theoretical and experimental works and developed a method to adapt the Remote Field Eddy Current technique which has been known and used for 30 years now. This document briefly recalls the basic principles of the Remote Field Eddy Current technique, the various steps of the works carried out and mainly describes examples of field inspection of ferromagnetic tubes and pipes [fr

  12. Targets with thin ferromagnetic layers for transient field experiments

    International Nuclear Information System (INIS)

    Gallant, J.L.; Dmytrenko, P.

    1982-01-01

    Multilayer targets containing a central layer sufficiently thin so that all recoil nuclei can traverse it and subsequently stop in a suitable cubic environment have been prepared. Such targets are required in experiments making use of a magnetic field acting on an ion moving through a ferromagnetic material. The preparation and annealing of the ferromagnetic foils (iron and gadolinium) and the fabrication of the multilayer targets are described. (orig.)

  13. Evidence of weak ferromagnetism in chromium(III) oxide particles

    International Nuclear Information System (INIS)

    Vazquez-Vazquez, Carlos; Banobre-Lopez, Manuel; Lopez-Quintela, M.A.; Hueso, L.E.; Rivas, J.

    2004-01-01

    The low temperature (4< T(K)<350) magnetic properties of chromium(III) oxide particles have been studied. A clear evidence of the presence of weak ferromagnetism is observed below 250 K. The magnetisation curves as a function of the applied field show coercive fields due to the canted antiferromagnetism of the particles. Around 55 K a maximum is observed in the zero-field-cooled curves; this maximum can be assumed as a blocking temperature, similarly to ultrafine ferromagnetic particles

  14. Magnetic nesting and co-existence of ferromagnetism and superconductivity

    International Nuclear Information System (INIS)

    Elesin, V.F.; Kapaev, V.V.; Kopaev, Yu.V.

    2004-01-01

    In the case of providing for the magnetic nesting conditions of the electron spin dispersion law the co-existence of ferromagnetism and superconductivity is possible by any high magnetization. The co-existence of ferromagnetism and superconductivity in the layered cuprate compounds of the RuSr 2 GdCu 2 O 8 -type is explained on this basis, wherein due to the nonstrict provision of the magnetic nesting condition there exists the finite but sufficiently high critical magnetization [ru

  15. Initial CAD investigations for NET

    International Nuclear Information System (INIS)

    Katz, F.; Leinemann, K.; Ludwig, A.; Marek, U.; Olbrich, W.; Schlechtendahl, E.G.

    1985-11-01

    This report summarizes the work done under contract no. 164/84-7/FU-D-/NET between the Commission of the European Communities and KfK during the period from June 1, 1984, through May 31, 1985. The following topics are covered in this report: Initial modelling of NET version NET2A, CAD system extension for remote handling studies, analysis of the CAD information structure, work related to the transfer of CAD information between KfK and the NET team. (orig.) [de

  16. Understanding Net Zero Energy Buildings

    DEFF Research Database (Denmark)

    Salom, Jaume; Widén, Joakim; Candanedo, José

    2011-01-01

    Although several alternative definitions exist, a Net-Zero Energy Building (Net ZEB) can be succinctly described as a grid-connected building that generates as much energy as it uses over a year. The “net-zero” balance is attained by applying energy conservation and efficiency measures...... and by incorporating renewable energy systems. While based on annual balances, a complete description of a Net ZEB requires examining the system at smaller time-scales. This assessment should address: (a) the relationship between power generation and building loads and (b) the resulting interaction with the power grid...

  17. Energy Dependence of Moments of Net-Proton Multiplicity Distributions at RHIC

    Czech Academy of Sciences Publication Activity Database

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C.; Aparin, A. A.; Arkhipkin, D.; Barnovská, Zuzana; Bielčík, J.; Bielčíková, Jana; Chaloupka, P.; Hajková, O.; Pachr, M.; Rusňák, Jan; Šumbera, Michal; Tlustý, David; Vértési, Robert

    2014-01-01

    Roč. 112, č. 3 (2014), 032302 ISSN 0031-9007 R&D Projects: GA ČR GA13-20841S Institutional support: RVO:61389005 Keywords : STAR * heavy ion collisions * proton and antiproton production Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 7.512, year: 2014

  18. Spin Orbit Torque in Ferromagnetic Semiconductors

    KAUST Repository

    Li, Hang

    2016-06-21

    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 be significantly improved. Hence, the manipulation of electron spin in electronic devices becomes more and more appealing for the advancement of microelectronics. In spin-based devices, the manipulation of ferromagnetic order parameter using electrical currents is a very useful means for current-driven operation. Nowadays, most of magnetic memory devices are based on the so-called spin transfer torque, which stems from the spin angular momentum transfer between a spin-polarized current and the magnetic order parameter. Recently, a novel spin torque effect, exploiting spin-orbit coupling in non-centrosymmetric magnets, has attracted a massive amount of attention. This thesis addresses the nature of spin-orbit coupled transport and torques in non-centrosymmetric magnetic semiconductors. We start with the theoretical study of spin orbit torque in three dimensional ferromagnetic GaMnAs. Using the Kubo formula, we calculate both the current-driven field-like torque and anti-damping-like torque. We compare the numerical results with the analytical expressions in the model case of a magnetic Rashba two-dimensional electron gas. Parametric dependencies of the different torque components and similarities to the analytical results of the Rashba two-dimensional electron gas in the weak disorder limit are described. Subsequently we study spin-orbit torques in two dimensional hexagonal crystals such as graphene, silicene, germanene and stanene. In the presence of staggered potential and exchange field, the valley degeneracy can be lifted and we obtain a valley-dependent Berry curvature, leading to a tunable antidamping torque by controlling the valley degree of freedom. This thesis then addresses the influence of the quantum spin Hall

  19. Net joint kinetics in the limbs of pigs walking on concrete floor in dry and contaminated conditions

    DEFF Research Database (Denmark)

    Thorup, Vivi M.; Laursen, Bjarne; Jensen, Bente Rona

    2008-01-01

    In pigs (Sus scrofa), joint disorders are frequent leg problems, and inappropriate pigpen floors and slippery floor conditions may contribute to these problems. Therefore, this study first aimed to quantify the net joint kinetics (net joint moments and net joint reaction forces) in the forelimbs...... and hindlimbs of healthy pigs walking on solid concrete floors. Second, this study aimed to examine the effect of floor condition on the net joint kinetics. Kinematic (50-Hz video recordings) and kinetic (1-kHz force plate measurements) data were collected from 30 pigs and combined with body segment parameters...... from a cadaver study. Net joint kinetics was calculated by using a 2-dimensional inverse dynamic solution. Inverse dynamics have, to our knowledge, not been applied in pigs before. Dry, greasy, and wet floor conditions were tested with 10 pigs each. In the forelimbs, peak joint moment was less (P

  20. Closed forms and multi-moment maps

    DEFF Research Database (Denmark)

    Madsen, Thomas Bruun; Swann, Andrew Francis

    2013-01-01

    We extend the notion of multi-moment map to geometries defined by closed forms of arbitrary degree. We give fundamental existence and uniqueness results and discuss a number of essential examples, including geometries related to special holonomy. For forms of degree four, multi-moment maps are gu...

  1. Magnetic moment of single layer graphene rings

    Science.gov (United States)

    Margulis, V. A.; Karpunin, V. V.; Mironova, K. I.

    2018-01-01

    Magnetic moment of single layer graphene rings is investigated. An analytical expression for the magnetic moment as a function of the magnetic field flux through the one-dimensional quantum rings is obtained. This expression has the oscillation character. The oscillation period is equal to one flux quanta.

  2. 6-quark contribution to nuclear magnetic moments

    International Nuclear Information System (INIS)

    Ito, H.

    1985-01-01

    The magnetic moments of nuclei with LS closed shell +/-1 particle are calculated. Core polarization and meson exchange current are treated realistically in order to single out the 6-quark contribution. Overall agreement with experimental values is quite good. It is shown that the 6-quark system contributes to the respective iso-vector and iso-scalar moments with reasonable magnitudes

  3. D-dimensional moments of inertia

    International Nuclear Information System (INIS)

    Bender, C.M.; Mead, L.R.

    1995-01-01

    We calculate the moments of inertia of D-dimensional spheres and spherical shells, where D is a complex number. We also examine the moments of inertia of fractional-dimensional geometrical objects such as the Cantor set and the Sierpinski carpet and their D-dimensional analogs. copyright 1995 American Association of Physics Teachers

  4. Dynamical moments of inertia for superdeformed nuclei

    International Nuclear Information System (INIS)

    Obikhod, T.V.

    1995-01-01

    The method of quantum groups has been applied for calculation the dynamical moments of inertia for the yrast superdeformed bands in 194 Hg and 192 Hg as well as to calculation of the dynamical moments of inertia of superdeformed bands in 150 Gd and 148 Gd

  5. Polarization electric dipole moment in nonaxial nuclei

    International Nuclear Information System (INIS)

    Denisov, V.Yu.; Davidovskaya, O.I.

    1996-01-01

    An expression for the macroscopic polarization electric dipole moment is obtained for nonaxial nuclei whose radii of the proton and neutron surfaces are related by a linear equation. Dipole transitions associated with the polarization electric dipole moment are analyzed for static and dynamical multipole deformations

  6. Droplet-model electric dipole moments

    International Nuclear Information System (INIS)

    Myers, W.D.; Swiatecki, W.J.

    1991-01-01

    Denisov's recent criticism of the droplet-model formula for the dipole moment of a deformed nucleus as derived by Dorso et al., it shown to be invalid. This helps to clarify the relation of theory to the measured dipole moments, as discussed in the review article by Aberg et al. (orig.)

  7. Teachable Moment: Google Earth Takes Us There

    Science.gov (United States)

    Williams, Ann; Davinroy, Thomas C.

    2015-01-01

    In the current educational climate, where clearly articulated learning objectives are required, it is clear that the spontaneous teachable moment still has its place. Authors Ann Williams and Thomas Davinroy think that instructors from almost any discipline can employ Google Earth as a tool to take advantage of teachable moments through the…

  8. Rare, but challenging tumors: NET

    International Nuclear Information System (INIS)

    Ivanova, D.; Balev, B.

    2013-01-01

    Full text: Introduction: Gastroenteropancreatic Neuroendocrine Tumors (GEP - NET) are a heterogeneous group of tumors with different locations and many different clinical, histological, and imaging performance. In a part of them a secretion of various organic substances is present. The morbidity of GEP - NET in the EU is growing, and this leads to increase the attention to them. What you will learn: Imaging methods used for localization and staging of GEP - NET, characteristics of the study’s protocols; Classification of GEP - NET; Demonstration of typical and atypical imaging features of GEP - NET in patients registered at the NET Center at University Hospital ‘St. Marina’, Varna; Features of metastatic NET, The role of imaging in the evaluation of treatment response and follow-up of the patients. Discussion: The image semiotics analysis is based on 19 cases of GEP - NET registered NET Center at University Hospital ‘St. Marina’. The main imaging method is multidetector CT (MDCT), and magnetic resonance imaging (MRI ) has advantages in the evaluation of liver lesions and the local prevalence of anorectal tumors. In patients with advanced disease and liver lesions the assessment of skeletal involvement (MRI/ nuclear medical method) is mandatory. The majority of GEP - NET have not any specific imaging findings. Therefore it is extremely important proper planning and conducting of the study (MDCT and MR enterography; accurate assessment phase of scanning, positive and negative contrast). Conclusion: GEP - NET is a major diagnostic challenge due to the absence of typical imaging characteristics and often an overlap with those of the tumors of different origin can be observed. Therefore, a good knowledge of clinical and imaging changes occurring at different locations is needed. MDCT is the basis for the diagnosis, staging and follow-up of these neoplasms

  9. Novel superconducting state in ferromagnetic superconductor UCoGe. Microscopic coexistence of ferromagnetism and superconductivity probed by 59Co-NQR measurements

    International Nuclear Information System (INIS)

    Ishida, Kenji; Hattori, Taisuke; Ihara, Yoshihiko; Nakai, Yusuke; Sato, Noriaki K.; Deguchi, Kazuhiko; Tamura, Nobuyuki; Satoh, Isamu

    2010-01-01

    We have investigated the relationship between ferromagnetism and superconductivity in ferromagnetic superconductor UCoGe from 59 Co nuclear quadrupole resonance (NQR) measurements. Our experimental results indicate the microscopic coexistence of ferromagnetism and superconductivity in UCoGe, and suggest a 'self-induced vortex state' in its superconducting state. We also review NQR experiments, which play an important role in this study. (author)

  10. TWO FERROMAGNETIC SPHERES IN HOMOGENEOUS MAGNETIC FIELD

    Directory of Open Access Journals (Sweden)

    Yury A. Krasnitsky

    2018-01-01

    Full Text Available The problem of two spherical conductors is studied quite in detail with bispherical coordinates usage and has numerous appendices in an electrostatics. The boundary-value problem about two ferromagnetic spheres enclosed on homogeneous and infinite environment in which the lack of spheres exists like homogeneous magnetic field is considered. The solution of Laplace's equation in the bispherical system of coordinates allows us to find the potential and field distribution in all spaces, including area between spheres. The boundary conditions in potential continuity and in ordinary density constituent of spheres surfaces induction flux are used. It is supposed that spheres are identical, and magnetic permeability of their material is expressed in  >> 0. The problem about falling of electromagnetic plane wave on the system of two spheres, which possesses electrically small sizes, can be considered as quasistationary. The scalar potentials received as a result of Laplace's equation solution are represented by the series containing Legendre polynomials. The concept of two spheres system effective permeability is introduced. It is equal to the advantage in magnitude of magnetic induction flux vector through a certain system’s section arising due to its magnetic properties. Necessary ratios for the effective permeability referred to the central system’s section are obtained. Particularly, the results can be used during the analysis of ferroxcube core clearance, which influences on the magnetic antenna properties. 

  11. Vortex precession in thin elliptical ferromagnetic nanodisks

    Energy Technology Data Exchange (ETDEWEB)

    Zaspel, C.E., E-mail: craig.zaspel@umwestern.edu

    2017-07-01

    Highlights: • A general form for the magnetostatic energy is calculated for the vortex state in a ferromagnetic ellipse. • The ellipse magnetostatic energy is minimized by conformal mapping the circular disk onto the ellipse. • The gyrotropic precession frequency is obtained in general for a range of ellipticities. - Abstract: The magnetostatic energy is calculated for a magnetic vortex in a noncircular elliptical nanodisk. It is well-known that the energy of a vortex in the circular disk is minimized though an ansatz that eliminates the magnetostatic charge at the disk edge. Beginning with this ansatz for the circular disk, a conformal mapping of a circle interior onto the interior of an ellipse results in the magnetization of the elliptical disk. This magnetization in the interior of an ellipse also has no magnetostatic charge at the disk edge also minimizing the magnetostatic energy. As expected the energy has a quadratic dependence on the displacement of the vortex core from the ellipse center, but reflecting the lower symmetry of the ellipse. Through numerical integration of the magnetostatic integral a general expression for the energy is obtained for ellipticity values from 1.0 to about 0.3. Finally a general expression for the gyrotropic frequency as described by the Thiele equation is obtained.

  12. Ferromagnetic resonance studies of lunar core stratigraphy

    Science.gov (United States)

    Housley, R. M.; Cirlin, E. H.; Goldberg, I. B.; Crowe, H.

    1976-01-01

    We first review the evidence which links the characteristic ferromagnetic resonance observed in lunar fines samples with agglutinatic glass produced primarily by micrometeorite impacts and present new results on Apollo 15, 16, and 17 breccias which support this link by showing that only regolith breccias contribute significantly to the characteristic FMR intensity. We then provide a calibration of the amount of Fe metal in the form of uniformly magnetized spheres required to give our observed FMR intensities and discuss the theoretical magnetic behavior to be expected of Fe spheres as a function of size. Finally, we present FMR results on samples from every 5 mm interval in the core segments 60003, 60009, and 70009. These results lead us to suggest: (1) that secondary mixing may generally be extensive during regolith deposition so that buried regolith surfaces are hard to recognize or define; and (2) that local grinding of rocks and pebbles during deposition may lead to short scale fluctuations in grain size, composition, and apparent exposure age of samples.

  13. Nuclear magnetic resonance in ferromagnetic terbium metal

    International Nuclear Information System (INIS)

    Cha, C.L.T.

    1974-01-01

    The magnetic properties of terbium were studied by the method of zero field nuclear magnetic resonance at 1.5 to 4 and 85 to 160 0 K. Two unconventional experimental techniques have been employed: the swept frequency and the swept temperature technique. Near 4 0 K, triplet resonance line structures were found and interpreted in terms of the magnetic domain and wall structures of ferromagnetic terbium. In the higher temperature range, temperature dependence of the resonance frequency and the quadrupole splitting were measured. The former provides a measurement of the temperature dependence of the magnetization M, and it agrees with bulk M measurements as well as the latest spin wave theory of M(T) (Brooks 1968). The latter agrees well with a calculation using a very general single ion density matrix for collective excitations (Callen and Shtrikman 1965). In addition, the small temperature-independent contribution to the electric field gradient at the nucleus due to the lattice and conduction electrons was untangled from the P(T) data. Also an anomalous and unexplained relaxation phenomenon was also observed

  14. Room temperature ferromagnetic gadolinium silicide nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Hadimani, Magundappa Ravi L.; Gupta, Shalabh; Harstad, Shane; Pecharsky, Vitalij; Jiles, David C.

    2018-03-06

    A particle usable as T1 and T2 contrast agents is provided. The particle is a gadolinium silicide (Gd5Si4) particle that is ferromagnetic at temperatures up to 290 K and is less than 2 .mu.m in diameter. An MRI contrast agent that includes a plurality of gadolinium silicide (Gd.sub.5Si.sub.4) particles that are less than 1 .mu.m in diameter is also provided. A method for creating gadolinium silicide (Gd5Si4) particles is also provided. The method includes the steps of providing a Gd5Si4 bulk alloy; grinding the Gd5Si4 bulk alloy into a powder; and milling the Gd5Si4 bulk alloy powder for a time of approximately 20 minutes or less.

  15. Ising-like spin anisotropy and competing antiferromagnetic-ferromagnetic orders in GdBaCo2O5.5 single crystals.

    Science.gov (United States)

    Taskin, A A; Lavrov, A N; Ando, Yoichi

    2003-06-06

    In RBaCo2O5+x compounds (R is rare earth), a ferromagnetic-antiferromagnetic competition is accompanied by a giant magnetoresistance. We study the magnetization of detwinned GdBaCo2O5.5 single crystals and find a remarkable uniaxial anisotropy of Co3+ spins which is tightly linked with the chain oxygen ordering in GdO0.5 planes. Reflecting the underlying oxygen order, CoO2 planes also develop a spin-state order consisting of Co3+ ions in alternating rows of S=1 and S=0 states. The magnetic structure appears to be composed of weakly coupled ferromagnetic ladders with Ising-like moments, which gives a simple picture for magnetotransport phenomena.

  16. Half-metallic ferromagnetism in full-Heusler compounds ACaX2 (A = K and Rb; X = N and O)

    International Nuclear Information System (INIS)

    Umamaheswari, R.; Vijayalakshmi, D.; Yogeswari, M.; Kalpana, G.

    2014-01-01

    Electronic structure and magnetic properties of hypothetical ACaX 2 (A = K and Rb; X= N and O) compounds in full-Heusler phase have been investigated based on density functional theory (DFT) within the local density approximation (LDA). The electronic band structures and density of states of these compounds show that the spin-down electrons have metallic, and the spin-up electrons have a semi conducting gap resulting in stable half-metallic ferromagnetic behaviour. The strong spin polarization of 2p states of N and O atoms is found to be the origin of ferromagnetism which results in a total magnetic moment of 3 μB and 1 μB respectively

  17. Linear Logic on Petri Nets

    DEFF Research Database (Denmark)

    Engberg, Uffe Henrik; Winskel, Glynn

    This article shows how individual Petri nets form models of Girard's intuitionistic linear logic. It explores questions of expressiveness and completeness of linear logic with respect to this interpretation. An aim is to use Petri nets to give an understanding of linear logic and give some apprai...

  18. Net neutrality and audiovisual services

    NARCIS (Netherlands)

    van Eijk, N.; Nikoltchev, S.

    2011-01-01

    Net neutrality is high on the European agenda. New regulations for the communication sector provide a legal framework for net neutrality and need to be implemented on both a European and a national level. The key element is not just about blocking or slowing down traffic across communication

  19. Properties of porous netted materials

    International Nuclear Information System (INIS)

    Daragan, V.D.; Drozdov, B.G.; Kotov, A.Yu.; Mel'nikov, G.N.; Pustogarov, A.V.

    1987-01-01

    Hydraulic and strength characteristics, efficient heat conduction and inner heat exchange coefficient are experimentally studied for porous netted materials on the base of the brass nets as dependent on porosity, cell size and method of net laying. Results of the studies are presented. It is shown that due to anisotropy of the material properties the hydraulic resistance in the direction parallel to the nets plane is 1.3-1.6 times higher than in the perpendicular one. Values of the effective heat conduction in the direction perpendicular to the nets plane at Π>0.45 agree with the data from literature, at Π<0.45 a deviation from the calculated values is marked in the direction of the heat conduction decrease

  20. NET remote workstation

    International Nuclear Information System (INIS)

    Leinemann, K.

    1990-10-01

    The goal of this NET study was to define the functionality of a remote handling workstation and its hardware and software architecture. The remote handling workstation has to fulfill two basic functions: (1) to provide the man-machine interface (MMI), that means the interface to the control system of the maintenance equipment and to the working environment (telepresence) and (2) to provide high level (task level) supporting functions (software tools) during the maintenance work and in the preparation phase. Concerning the man-machine interface, an important module of the remote handling workstation besides the standard components of man-machine interfacing is a module for graphical scene presentation supplementing viewing by TV. The technique of integrated viewing is well known from JET BOOM and TARM control using the GBsim and KISMET software. For integration of equipment dependent MMI functions the remote handling workstation provides a special software module interface. Task level support of the operator is based on (1) spatial (geometric/kinematic) models, (2) remote handling procedure models, and (3) functional models of the equipment. These models and the related simulation modules are used for planning, programming, execution monitoring, and training. The workstation provides an intelligent handbook guiding the operator through planned procedures illustrated by animated graphical sequences. For unplanned situations decision aids are available. A central point of the architectural design was to guarantee a high flexibility with respect to hardware and software. Therefore the remote handling workstation is designed as an open system based on widely accepted standards allowing the stepwise integration of the various modules starting with the basic MMI and the spatial simulation as standard components. (orig./HP) [de

  1. Valley and spin resonant tunneling current in ferromagnetic/nonmagnetic/ferromagnetic silicene junction

    Directory of Open Access Journals (Sweden)

    Yaser Hajati

    2016-02-01

    Full Text Available We study the transport properties in a ferromagnetic/nonmagnetic/ferromagnetic (FNF silicene junction in which an electrostatic gate potential, U, is attached to the nonmagnetic region. We show that the electrostatic gate potential U is a useful probe to control the band structure, quasi-bound states in the nonmagnetic barrier as well as the transport properties of the FNF silicene junction. In particular, by introducing the electrostatic gate potential, both the spin and valley conductances of the junction show an oscillatory behavior. The amplitude and frequency of such oscillations can be controlled by U. As an important result, we found that by increasing U, the second characteristic of the Klein tunneling is satisfied as a result of the quasiparticles chirality which can penetrate through a potential barrier. Moreover, it is found that for special values of U, the junction shows a gap in the spin and valley-resolve conductance and the amplitude of this gap is only controlled by the on-site potential difference, Δz. Our findings of high controllability of the spin and valley transport in such a FNF silicene junction may improve the performance of nano-electronics and spintronics devices.

  2. Electrical detection of ferromagnetic resonance in ferromagnet/n-GaAs heterostructures by tunneling anisotropic magnetoresistance

    Energy Technology Data Exchange (ETDEWEB)

    Liu, C.; Boyko, Y.; Geppert, C. C.; Christie, K. D.; Stecklein, G.; Crowell, P. A., E-mail: crowell@physics.umn.edu [School of Physics and Astronomy, University of Minnesota, Minneapolis, Minnesota 55455 (United States); Patel, S. J. [Department of Materials, University of California, Santa Barbara, California 93106 (United States); Palmstrøm, C. J. [Department of Materials, University of California, Santa Barbara, California 93106 (United States); Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

    2014-11-24

    We observe a dc voltage peak at ferromagnetic resonance (FMR) in samples consisting of a single ferromagnetic (FM) layer grown epitaxially on the n-GaAs (001) surface. The FMR peak is detected as an interfacial voltage with a symmetric line shape and is present in samples based on various FM/n-GaAs heterostructures, including Co{sub 2}MnSi/n-GaAs, Co{sub 2}FeSi/n-GaAs, and Fe/n-GaAs. We show that the interface bias voltage dependence of the FMR signal is identical to that of the tunneling anisotropic magnetoresistance (TAMR) over most of the bias range. Furthermore, we show how the precessing magnetization yields a dc FMR signal through the TAMR effect and how the TAMR phenomenon can be used to predict the angular dependence of the FMR signal. This TAMR-induced FMR peak can be observed under conditions where no spin accumulation is present and no spin-polarized current flows in the semiconductor.

  3. Current-induced damping of nanosized quantum moments in the presence of spin-orbit interaction

    Science.gov (United States)

    Mahfouzi, Farzad; Kioussis, Nicholas

    2017-05-01

    Motivated by the need to understand current-induced magnetization dynamics at the nanoscale, we have developed a formalism, within the framework of Keldysh Green function approach, to study the current-induced dynamics of a ferromagnetic (FM) nanoisland overlayer on a spin-orbit-coupling (SOC) Rashba plane. In contrast to the commonly employed classical micromagnetic LLG simulations the magnetic moments of the FM are treated quantum mechanically. We obtain the density matrix of the whole system consisting of conduction electrons entangled with the local magnetic moments and calculate the effective damping rate of the FM. We investigate two opposite limiting regimes of FM dynamics: (1) The precessional regime where the magnetic anisotropy energy (MAE) and precessional frequency are smaller than the exchange interactions and (2) the local spin-flip regime where the MAE and precessional frequency are comparable to the exchange interactions. In the former case, we show that due to the finite size of the FM domain, the "Gilbert damping" does not diverge in the ballistic electron transport regime, in sharp contrast to Kambersky's breathing Fermi surface theory for damping in metallic FMs. In the latter case, we show that above a critical bias the excited conduction electrons can switch the local spin moments resulting in demagnetization and reversal of the magnetization. Furthermore, our calculations show that the bias-induced antidamping efficiency in the local spin-flip regime is much higher than that in the rotational excitation regime.

  4. On multipole moments in general relativity

    International Nuclear Information System (INIS)

    Hoenselaers, C.

    1986-01-01

    In general situations, involving gravitational waves the question of multiple moments in general relativity restricts the author to stationary axisymmetric situations. Here it has been shown that multipole moments, a set of numbers defined at spatial infinity as far away from the source as possible, determine a solution of Einstein's equations uniquely. With the rather powerful methods for generating solutions one might hope to get solutions with predefined multipole moments. Before doing so, however, one needs an efficient algorithm for calculating the moments of a given solution. Chapter 2 deals with a conjecture pertaining to such a calculational procedure and shows it to be not true. There is another context in which multipole moments are important. Consider a system composed of several objects. To separate, if possible, the various parts of their interaction, one needs a definition for multipole moments of individual members of a many body system. In spite of the fact that there is no definition for individual moments, with the exception of mass and angular momentum, Chapter 3 shows what can be done for the double Kerr solution. The authors can identify various terms in he interaction of two aligned Kerr objects and show that gravitational spin-spin interaction is indeed proportional to the product of the angular momenta

  5. Table of Nuclear Electric Quadrupole Moments

    International Nuclear Information System (INIS)

    Stone, N.J.

    2013-12-01

    This Table is a compilation of experimental measurements of static electric quadrupole moments of ground states and excited states of atomic nuclei throughout the periodic table. To aid identification of the states, their excitation energy, half-life, spin and parity are given, along with a brief indication of the method and any reference standard used in the particular measurement. Experimental data from all quadrupole moment measurements actually provide a value of the product of the moment and the electric field gradient [EFG] acting at the nucleus. Knowledge of the EFG is thus necessary to extract the quadrupole moment. A single recommended value of the moment is given for each state, based, for each element, wherever possible, upon a standard reference moment for a nuclear state of that element studied in a situation in which the electric field gradient has been well calculated. For several elements one or more subsidiary reference EFG/moment references are required and their use is specified. The literature search covers the period to mid-2013. (author)

  6. Theory of nuclear magnetic moments - LT-35

    Energy Technology Data Exchange (ETDEWEB)

    Kerman, A. K.

    1952-09-15

    The purpose of these notes is to give an account of some attempts at interpreting the observed values of nuclear magnetic moments. There is no attempt at a complete summary of the field as that would take much more space than is used here. In many cases the arguments are only outlined and references are given for those interested in further details. A discussion of the theory of nuclear magnetic moments necessitates many excursions into the details of the nuclear models because the magnetic moments have a direct bearing on the validity of these models. However the main emphasis here is on those features which tend to explain the magnetic moments and other evidence is not discussed unless it has a direct bearing on the problem. In the first part of the discussion the Shell Model of the nucleus is used, as this model seems to correlate a large body of data relating to the heavier nuclei. Included here are the modifications proposed to explain the fact that the experimental magnetic moments do not fit quantitatively with the exact predictions of the Shell Model. The next sections deal with some of the more drastic modifications introduced to explain the large nuclear quadrupole moments and the effect of these modifications on the magnetic moments. Finally we turn to more detailed investigations of the light nuclei, in particular the - Conjugate nuclei. (author)

  7. Magnetic behavior of clusters of ferromagnetic transition metals

    DEFF Research Database (Denmark)

    Khanna, S. N.; Linderoth, Søren

    1991-01-01

    The effective magnetic moments of small iron and cobalt clusters have been calculated by assuming that the clusters undergo superparamagnetic relaxation. The effective moments per atom are found to be much below the bulk values, even at low temperatures (100 K). They increase with particle size a...... moments in small clusters compared to bulk as being due to melting of surface spins....

  8. Moments analysis of concurrent Poisson processes

    International Nuclear Information System (INIS)

    McBeth, G.W.; Cross, P.

    1975-01-01

    A moments analysis of concurrent Poisson processes has been carried out. Equations are given which relate combinations of distribution moments to sums of products involving the number of counts associated with the processes and the mean rate of the processes. Elimination of background is discussed and equations suitable for processing random radiation, parent-daughter pairs in the presence of background, and triple and double correlations in the presence of background are given. The theory of identification of the four principle radioactive series by moments analysis is discussed. (Auth.)

  9. Exchange currents for hypernuclear magnetic moments

    International Nuclear Information System (INIS)

    Saito, K.; Oka, M.; Suzuki, T.

    1997-01-01

    The meson (K and π) exchange currents for the hypernuclear magnetic moments are calculated using the effective Lagrangian method. The seagull diagram, the mesonic diagram and the Σ 0 -excitation diagram are considered. The Λ-N exchange magnetic moments for 5 Λ He and A=6 hypernuclei are calculated employing the harmonic oscillator shell model. It is found that the two-body correction is about -9% of the single particle value for 5 Λ He. The π exchange current, induced only in the Σ 0 -excitation diagram, is found to give dominant contribution for the isovector magnetic moments of hypernuclei with A=6. (orig.)

  10. Moment analysis of hadronic vacuum polarization

    Directory of Open Access Journals (Sweden)

    Eduardo de Rafael

    2014-09-01

    Full Text Available I suggest a new approach to the determination of the hadronic vacuum polarization (HVP contribution to the anomalous magnetic moment of the muon aμHVP in lattice QCD. It is based on properties of the Mellin transform of the hadronic spectral function and their relation to the HVP self-energy in the Euclidean. I show how aμHVP is very well approximated by a few moments associated to this Mellin transform and how these moments can be evaluated in lattice QCD, providing thus a series of tests when compared with the corresponding determinations using experimental data.

  11. Moment analysis of hadronic vacuum polarization

    International Nuclear Information System (INIS)

    Rafael, Eduardo de

    2014-01-01

    I suggest a new approach to the determination of the hadronic vacuum polarization (HVP) contribution to the anomalous magnetic moment of the muon a μ HVP in lattice QCD. It is based on properties of the Mellin transform of the hadronic spectral function and their relation to the HVP self-energy in the Euclidean. I show how a μ HVP is very well approximated by a few moments associated to this Mellin transform and how these moments can be evaluated in lattice QCD, providing thus a series of tests when compared with the corresponding determinations using experimental data

  12. Moment analysis of hadronic vacuum polarization

    Energy Technology Data Exchange (ETDEWEB)

    Rafael, Eduardo de

    2014-09-07

    I suggest a new approach to the determination of the hadronic vacuum polarization (HVP) contribution to the anomalous magnetic moment of the muon a{sub μ}{sup HVP} in lattice QCD. It is based on properties of the Mellin transform of the hadronic spectral function and their relation to the HVP self-energy in the Euclidean. I show how a{sub μ}{sup HVP} is very well approximated by a few moments associated to this Mellin transform and how these moments can be evaluated in lattice QCD, providing thus a series of tests when compared with the corresponding determinations using experimental data.

  13. Moment approach to charged particle beam dynamics

    International Nuclear Information System (INIS)

    Channell, P.J.

    1983-01-01

    We have derived the hierarchy of moment equations that describes the dynamics of charged-particle beams in linear accelerators and can truncate the hierarchy at any level either by discarding higher moments or by a cumulant expansion discarding only correlation functions. We have developed a procedure for relating the density expansion linearly to the moments to any order. The relation of space-charge fields to the density has been derived; and an accurate, systematic, and computationally convenient expansion of the resultant integrals has been developed

  14. Dipole moments of the rho meson

    International Nuclear Information System (INIS)

    Hecht, M.B.; McKellar, B.H.P.

    1997-04-01

    The electric and magnetic dipole moments (EDM) of the rho meson are calculated using the propagators and vertices derived from the quantum chromodynamics Dyson-Schwinger equations. Results obtained from using the Bethe-Salpeter amplitude studied by Chappell, Mitchell et. al., and Pichowsky and Lee, are compared. The rho meson EDM is generated through the inclusion of a quark electric dipole moment, which is left as a free variable. These results are compared to the perturbative results to obtain a measure of the effects of quark interactions and confinement. The two dipole moments are also calculated using the phenomenological MIT bag model to provide a further basis for comparison

  15. Moments method in the theory of accelerators

    International Nuclear Information System (INIS)

    Perel'shtejn, Eh.A.

    1984-01-01

    The moments method is widely used for solution of different physical and calculation problems in the theory of accelerators, magnetic optics and dynamics of high-current beams. Techniques using moments of the second order-mean squape characteristics of charged particle beams is shown to be most developed. The moments method is suitable and sometimes even the only technique applicable for solution of computerized problems on optimization of accelerating structures, beam transport channels, matching and other systems with accout of a beam space charge

  16. Intra-event correlations and the statistical moments of the identified particle multiplicity distributions in the RHIC beam energy scan data collected by STAR

    Science.gov (United States)

    Llope, W. J.; STAR Collaboration

    2013-10-01

    Specific products of the statistical moments of the multiplicity distributions of identified particles can be directly compared to susceptibility ratios obtained from lattice QCD calculations. They may also diverge for nuclear systems formed close to a possible QCD critical point due to the phenomenon of critical opalescence. Of particular interest are the moments products for net-protons, net-kaons, and net-charge, as these are considered proxies for conserved quantum numbers. The moments products have been measured by the STAR experiment for Au+Au collisions at seven beam energies ranging from 7.7 to 200 GeV. In this presentation, the experimental results are compared to data-based calculations in which the intra-event correlations of the numbers of positive and negative particles are broken by construction. The importance of intra-event correlations to the moments products values for net-protons, net-kaons, and net-charge can thus be evaluated. Work supported by the U.S. Dept of Energy under grant DE-PS02-09ER09.

  17. Fe magnetic moment formation and exchange interaction in Fe{sub 2}P: A first-principles study

    Energy Technology Data Exchange (ETDEWEB)

    Liu, X.B., E-mail: liuxubo@uta.edu [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Ping Liu, J.; Zhang, Qiming [Department of Physics, University of Texas at Arlington, Arlington, TX 76019 (United States); Altounian, Z. [Center for the Physics of Materials and Department of Physics, McGill University, 3600 University Street, Montreal, Quebec, H3A 2T8 (Canada)

    2013-03-15

    Electronic structure and magnetic properties of Fe{sub 2}P have been studied by a first-principles density functional theory calculation. The ground state is ferromagnetic and the calculated magnetic moments for Fe{sub 1} (3f) and Fe{sub 2} (3g) are 0.83 and 2.30μ{sub B}, respectively. The nearest neighbor inter-site magnetic exchange coupling parameter at the Fe{sub 1} layer (0.02 mRy) is much smaller than that at the Fe{sub 2} layer (1.29 mRy). The Fe moment at the 3f site is metastable and sensitive to the inter-site exchange interaction with its magnetic neighbors, which is responsible for the first order magnetic transition and large magneto-caloric effect around T{sub C}.

  18. Conformal Nets II: Conformal Blocks

    Science.gov (United States)

    Bartels, Arthur; Douglas, Christopher L.; Henriques, André

    2017-08-01

    Conformal nets provide a mathematical formalism for conformal field theory. Associated to a conformal net with finite index, we give a construction of the `bundle of conformal blocks', a representation of the mapping class groupoid of closed topological surfaces into the category of finite-dimensional projective Hilbert spaces. We also construct infinite-dimensional spaces of conformal blocks for topological surfaces with smooth boundary. We prove that the conformal blocks satisfy a factorization formula for gluing surfaces along circles, and an analogous formula for gluing surfaces along intervals. We use this interval factorization property to give a new proof of the modularity of the category of representations of a conformal net.

  19. Pro asynchronous programming with .NET

    CERN Document Server

    Blewett, Richard; Ltd, Rock Solid Knowledge

    2014-01-01

    Pro Asynchronous Programming with .NET teaches the essential skill of asynchronous programming in .NET. It answers critical questions in .NET application development, such as: how do I keep my program responding at all times to keep my users happy how do I make the most of the available hardware how can I improve performanceIn the modern world, users expect more and more from their applications and devices, and multi-core hardware has the potential to provide it. But it takes carefully crafted code to turn that potential into responsive, scalable applications.With Pro Asynchronous Programming

  20. Defect mediated reversible ferromagnetism in Co and Mn doped zinc oxide epitaxial films

    Energy Technology Data Exchange (ETDEWEB)

    Mal, Siddhartha; Nori, Sudhakar; Narayan, J. [Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Mula, Suhrit [Department of Material Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Department of Metallurgical and Materials Engineering, National Institute of Technology, Rourkela 769008 (India); Prater, J. T. [Materials Science Division, Army Research Office, Research Triangle Park, North Carolina 27709 (United States)

    2012-12-01

    We have introduced defects in ZnO (undoped and doped with Co and Mn) epitaxial thin films using laser irradiation from nanosecond laser pulses and thermal annealing in oxygen ambient. In contrast to the as grown samples, the laser irradiated films show a significant increase in conductivity, enhancement in UV emission, while maintaining the same wurtzite crystal structure. Room-temperature ferromagnetism (RTFM) is observed in laser-irradiated samples, which increased with the number of laser pulses up to a certain value where magnetic moment saturates. The induced ferromagnetism as well as the enhanced electrical conductivity can be reversed with thermal annealing in oxygen ambient. The magnetization in Co and Mn doped films was found to be strong function of growth conditions and defect concentration. X-ray diffraction and optical absorption experiments suggested a 2+ valance state and tetrahedral coordination for both Co and Mn ions. There is a simultaneous increase in n-type electrical conductivity with the number of laser pulses and continue to exhibit semiconducting behavior in both undoped and doped films. The saturation magnetization was found to be 0.08 {mu}{sub B}/Co and 0.05 {mu}{sub B}/Mn, much lower than 3.0 {mu}{sub B}/Co and 5.0 {mu}{sub B}/Mn, indicating the prominent role of intrinsic defects in RTFM with some contribution from Co{sup 2+}-oxygen vacancy complexes. We propose a unified mechanism based upon introduction of intrinsic defects to explain RTFM and n-type conductivity enhancements during pulsed laser and thermal annealing.