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Articles 1  30 of 180
FullText Articles in Physics
Generalized Magnetoelectronic Circuit Theory And Spin Relaxation At Interfaces In Magnetic Multilayers, G. G. Baez Flores, Alexey Kovalev, Mark Van Schilfgaarde, K. D. Belashchenko
Generalized Magnetoelectronic Circuit Theory And Spin Relaxation At Interfaces In Magnetic Multilayers, G. G. Baez Flores, Alexey Kovalev, Mark Van Schilfgaarde, K. D. Belashchenko
Faculty Publications, Department of Physics and Astronomy
Spin transport at metallic interfaces is an essential ingredient of various spintronic device concepts, such as giant magnetoresistance, spintransfer torque, and spin pumping. Spinorbit coupling plays an important role in many such devices. In particular, spin current is partially absorbed at the interface due to spinorbit coupling. We develop a general magnetoelectronic circuit theory and generalize the concept of spinmixing conductance, accounting for various mechanisms responsible for spinflip scattering. For the special case when exchange interactions dominate, we give a simple expression for the spinmixing conductance in terms of the contributions responsible for spin relaxation (i.e., spin memory loss ...
Interfacial Contributions To SpinOrbit Torque And Magnetoresistance In Ferromagnet/HeavyMetal Bilayers, Kirill Belashchenko, Alexey Kovalev, Mark Van Schilfgaarde
Interfacial Contributions To SpinOrbit Torque And Magnetoresistance In Ferromagnet/HeavyMetal Bilayers, Kirill Belashchenko, Alexey Kovalev, Mark Van Schilfgaarde
Faculty Publications, Department of Physics and Astronomy
The thickness dependence of spinorbit torque and magnetoresistance in ferromagnet/heavymetal bilayers is studied using the ﬁrstprinciples nonequilibrium Green’s function formalism combined with the Anderson disorder model. A systematic expansion in orthogonal vector spherical harmonics is used for the angular dependence of the torque. The dampinglike torque in Co/Pt and Co/Au bilayers can be described as a sum of the spinHall contribution, which increases with thickness in agreement with the spindiffusion model, and a comparable interfacial contribution. The magnetoconductance in the plane perpendicular to the current in Co/Pt bilayers is of the order of a conductance ...
Intrinsic Spin Nernst Effect Of Magnons In A Noncollinear Antiferromagnet, Bo Li, Shane Sandhoefner, Alexey Kovalev
Intrinsic Spin Nernst Effect Of Magnons In A Noncollinear Antiferromagnet, Bo Li, Shane Sandhoefner, Alexey Kovalev
Faculty Publications, Department of Physics and Astronomy
We investigate the intrinsic magnon spin current in a noncollinear antiferromagnetic insulator. We introduce a deﬁnition of the magnon spin current in a noncollinear antiferromagnet and ﬁnd that it is in general nonconserved, but for certain symmetries and spin polarizations the averaged effect of nonconserving terms can vanish. We formulate a general linear response theory for magnons in noncollinear antiferromagnets subject to a temperature gradient and analyze the effect of symmetries on the response tensor. We apply this theory to singlelayer potassium iron jarosite KFe3(OH)6(SO4)2 and predict a measurable spin current response.
Magnonic Analog Of The Edelstein Effect In Antiferromagnetic Insulators, Bo Li, Alexander Mook, Aldo Raeliarijaona, Alexey Kovalev
Magnonic Analog Of The Edelstein Effect In Antiferromagnetic Insulators, Bo Li, Alexander Mook, Aldo Raeliarijaona, Alexey Kovalev
Faculty Publications, Department of Physics and Astronomy
We investigate the nonequilibrium spin polarization due to a temperature gradient in antiferromagnetic insulators, which is the magnonic analog of the inverse spingalvanic effect of electrons. We derive a linearresponse theory of a temperaturegradientinduced spin polarization for collinear and noncollinear antiferromagnets, which comprises both extrinsic and intrinsic contributions. We apply our theory to several noncentrosymmetric antiferromagnetic insulators, i.e., to a onedimensional antiferromagnetic spin chain, a single layer of kagome noncollinear antiferromagnet,e.g.,KFe3(OH)6(SO4)2,and a noncollinear breathing pyrochlore antiferromagnet, e.g., LiGaCr4O8. The shapes of our numerically evaluated response tensors agree with those implied ...
Testing Quantum Coherence In Stochastic Electrodynamics With Squeezed Schrödinger Cat States, Wayne ChengWei Huang, Herman Batelaan
Testing Quantum Coherence In Stochastic Electrodynamics With Squeezed Schrödinger Cat States, Wayne ChengWei Huang, Herman Batelaan
Faculty Publications, Department of Physics and Astronomy
The interference pattern in electron doubleslit diffraction is a hallmark of quantum mechanics. A longstanding question for stochastic electrodynamics (SED) is whether or not it is capable of reproducing such effects, as interference is a manifestation of quantum coherence. In this study, we used excited harmonic oscillators to directly test this quantum feature in SED. We used two counterpropagating dichromatic laser pulses to promote a groundstate harmonic oscillator to a squeezed Schrödinger cat state. Upon recombination of the two wellseparated wavepackets, an interference pattern emerges in the quantum probability distribution but is absent in the SED probability distribution. We thus ...
ValleyDependent Lorentz Force And AharonovBohm Phase In Strained Graphene PN Junction, Sanjay Prabhakar, Rabindra Nepal, Roderick Melnik, Alexey Kovalev
ValleyDependent Lorentz Force And AharonovBohm Phase In Strained Graphene PN Junction, Sanjay Prabhakar, Rabindra Nepal, Roderick Melnik, Alexey Kovalev
Faculty Publications, Department of Physics and Astronomy
Veselago lens focusing in graphene p−n junction is promising for realizations of new generation electron optics devices. However, the effect of the straininduced AharonovBohm interference in a p−n junction has not been discussed before. We provide an experimentally feasible setup based on the Veselago lens in which the presence of strain can result in both the valleydependent Lorentz force and AharonovBohm interference. In particular, by employing the Green's function and tightbinding methods, we study the strain induced by dislocations and line defects in a p−n junction and show how the resulting AharonovBohm phase and interference can ...
Systems And Methods For Scalable Perovskite Device Fabrication, Jinsong Huang, Qingfeng Dong, Yuchuan Shao
Systems And Methods For Scalable Perovskite Device Fabrication, Jinsong Huang, Qingfeng Dong, Yuchuan Shao
Faculty Publications, Department of Physics and Astronomy
Continuous processes for fabricating a perovskite device are described that include forming a perovskite layer or film on a substrate using a linear deposition device , and optionally using a conductive tape lamination process to form an anode or a cathode layer on the perovskite device .
Magnetoelectric Control Of Topological Phases In Graphene, Hiroyuki Takenaka, Shane Sandhoefner, Alexey Kovalev, Evgeny Tsymbal
Magnetoelectric Control Of Topological Phases In Graphene, Hiroyuki Takenaka, Shane Sandhoefner, Alexey Kovalev, Evgeny Tsymbal
Faculty Publications, Department of Physics and Astronomy
Topological antiferromagnetic (AFM) spintronics is an emerging field of research, which involves the topological electronic states coupled to the AFM order parameter known as the Néel vector. The control of these states is envisioned through manipulation of the Néel vector by spinorbit torques driven by electric currents. Here we propose a different approach favorable for lowpower AFM spintronics, where the control of the topological states in a twodimensional material, such as graphene, is performed via the proximity effect by the voltage induced switching of the Néel vector in an adjacent magnetoelectric AFM insulator, such as chromia. Mediated by the symmetry ...
Duality And Free Energy Analyticity Bounds For FewBody Ising Models With Extensive Homology Rank, Yi Jiang, Ilya Dumer, Alexey Kovalev, Leonid Pryadko
Duality And Free Energy Analyticity Bounds For FewBody Ising Models With Extensive Homology Rank, Yi Jiang, Ilya Dumer, Alexey Kovalev, Leonid Pryadko
Faculty Publications, Department of Physics and Astronomy
We consider pairs of fewbody Ising models where each spin enters a bounded number of interaction terms (bonds) such that each model can be obtained from the dual of the other after freezing k spins on largedegree sites. Such a pair of Ising models can be interpreted as a twochain complex with k being the rank of the first homology group. Our focus is on the case where k is extensive, that is, scales linearly with the number of bonds n. Flipping any of these additional spins introduces a homologically nontrivial defect (generalized domain wall). In the presence of bond ...
Boundary Twists, Instabilities, And Creation Of Skyrmions And Antiskyrmions, Aldo Raeliarijaona, Rabindra Nepal, Alexey Kovalev
Boundary Twists, Instabilities, And Creation Of Skyrmions And Antiskyrmions, Aldo Raeliarijaona, Rabindra Nepal, Alexey Kovalev
Faculty Publications, Department of Physics and Astronomy
We formulate and study the general boundary conditions dictating the magnetization profile in the vicinity of an interface between magnets with dissimilar properties. Boundary twists in the vicinity of an edge due to DzyaloshinskiiMoriya interactions have been first discussed by Wilson et al. [Phys. Rev. B 88, 214420 (2013)] and by Rohart and Thiaville [Phys. Rev. B 88, 184422 (2013)]. We show that in general case the boundary conditions lead to the magnetization profile corresponding to the Néel, Bloch, or intermediate twist. We explore how such twists can be utilized for creation of skyrmions and antiskyrmions, e.g., in a ...
FirstPrinciples Calculation Of The SpinOrbit Torques In A Co/Pt Bilayer, K. D. Belashchenko, Alexey A. Kovalev, M. Van Schilfgaarde
FirstPrinciples Calculation Of The SpinOrbit Torques In A Co/Pt Bilayer, K. D. Belashchenko, Alexey A. Kovalev, M. Van Schilfgaarde
Faculty Publications, Department of Physics and Astronomy
The spinorbit torque in a disordered Co/Pt bilayer is calculated using a firstprinciples nonequilibrium Green's function formalism. The torque is formally split in the Fermisea and Fermisurface contributions. The Fermisea term is important at low temperatures, but the Fermisurface term dominates at room temperature. In addition to the usual dampinglike and fieldlike terms, the odd torque contains a sizeable planar Halllike term (m . E)m x (z x m) which contributes to damping. While the torques that contribute to damping are almost entirely due to spinorbit coupling on the Pt atoms, the fieldlike torque does not require it.
Probing Tunneling Spin Injection Into Graphene Via Bias Dependence, Tiancong Zhu, Simranjeet Singh, Jyoti Katoch, Hua Wen, Kirill Belashchenko, Igor Zutic, Roland K. Kawakami
Probing Tunneling Spin Injection Into Graphene Via Bias Dependence, Tiancong Zhu, Simranjeet Singh, Jyoti Katoch, Hua Wen, Kirill Belashchenko, Igor Zutic, Roland K. Kawakami
Faculty Publications, Department of Physics and Astronomy
The bias dependence of spin injection in graphene lateral spin valves is systematically studied to determine the factors affecting the tunneling spin injection efficiency. Three types of junctions are investigated, including MgO and hexagonal boron nitride (hBN) tunnel barriers and direct contacts. A dc bias current applied to the injector electrode induces a strong nonlinear bias dependence of the nonlocal spin signal for both MgO and hBN tunnel barriers. Furthermore, this signal reverses its sign at a negative dc bias for both kinds of tunnel barriers. The analysis of the bias dependence for injector electrodes with a wide range of ...
Numerical And Analytical Bounds On Threshold Error Rates For HypergraphProduct Codes, Alexey Kovalev, Sanjay Prabhakar, Ilya Dumer, Leonid P. Pryadko
Numerical And Analytical Bounds On Threshold Error Rates For HypergraphProduct Codes, Alexey Kovalev, Sanjay Prabhakar, Ilya Dumer, Leonid P. Pryadko
Faculty Publications, Department of Physics and Astronomy
We study analytically and numerically decoding properties of finiterate hypergraphproduct quantum low density paritycheck codes obtained from random (3,4)regular Gallager codes, with a simple model of independent X and Z errors. Several nontrivial lower and upper bounds for the decodable region are constructed analytically by analyzing the properties of the homological difference, equal minus the logarithm of the maximumlikelihood decoding probability for a given syndrome. Numerical results include an upper bound for the decodable region from specific heat calculations in associated Ising models and a minimumweight decoding threshold of approximately 7%.
Chiral Topological Insulator Of Magnons, Bo Li, Alexey Kovalev
Chiral Topological Insulator Of Magnons, Bo Li, Alexey Kovalev
Faculty Publications, Department of Physics and Astronomy
We propose a magnon realization of 3D topological insulator in the AIII (chiral symmetry) topological class. The topological magnon gap opens due to the presence of DzyaloshinskiiMoriya interactions. The existence of the topological invariant is established by calculating the bulk winding number of the system. Within our model, the surface magnon Dirac cone is protected by the sublattice chiral symmetry. By analyzing the magnon surface modes, we confirm that the backscattering is prohibited. By weakly breaking the chiral symmetry, we observe the magnon Hall response on the surface due to opening of the gap. Finally, we show that by changing ...
Proximitized Materials, Igor Žutić, Alex MatosAbiague, Benedikt Scharf, Hanan Dery, Kirill Belashchenko
Proximitized Materials, Igor Žutić, Alex MatosAbiague, Benedikt Scharf, Hanan Dery, Kirill Belashchenko
Faculty Publications, Department of Physics and Astronomy
Advances in scaling down heterostructures and having an improved interface quality together with atomically thin twodimensional materials suggest a novel approach to systematically design materials. A given material can be transformed through proximity effects whereby it acquires properties of its neighbors, for example, becoming superconducting, magnetic, topologically nontrivial, or with an enhanced spinorbit coupling. Such proximity effects not only complement the conventional methods of designing materials by doping or functionalization but can also overcome their various limitations. In proximitized materials it is possible to realize properties that are not present in any constituent region of the considered heterostructure. While the ...
Origin Of Spin Reorientation Transitions In Antiferromagnetic MnptBased Alloys, P.H. Chang, I. A. Zhuravlev, K. D. Belashchenko
Origin Of Spin Reorientation Transitions In Antiferromagnetic MnptBased Alloys, P.H. Chang, I. A. Zhuravlev, K. D. Belashchenko
Faculty Publications, Department of Physics and Astronomy
Antiferromagnetic MnPt exhibits a spin reorientation transition (SRT) as a function of temperature, and offstoichiometric MnPt alloys also display SRTs as a function of concentration. The magnetocrystalline anisotropy in these alloys is studied using firstprinciples calculations based on the coherent potential approximation and the disordered local moment method. The anisotropy is fairly small and sensitive to the variations in composition and temperature due to the cancellation of large contributions from different parts of the Brillouin zone. Concentration and temperaturedriven SRTs are found in reasonable agreement with experimental data. Contributions from specific bandstructure features are identified and used to explain the ...
Magnetic Skyrmion Bubble Motion Driven By Surface Acoustic Waves, Rabindra Nepal, Utkan Güngördü, Alexey Kovalev
Magnetic Skyrmion Bubble Motion Driven By Surface Acoustic Waves, Rabindra Nepal, Utkan Güngördü, Alexey Kovalev
Faculty Publications, Department of Physics and Astronomy
We study the dynamical control of a magnetic skyrmion bubble by using counterpropagating surface acoustic waves (SAWs) in a ferromagnet. First, we determine the bubble mass and derive the force due to SAWs acting on a magnetic bubble using Thiele's method. The force that pushes the bubble is proportional to the strain gradient for the major strain component. We then study the dynamical pinning and motion of magnetic bubbles by SAWs in a nanowire. In a disk geometry, we propose a SAWsdriven skyrmion bubble oscillator with two resonant frequencies.
Stabilization And Control Of Majorana Bound States With Elongated Skyrmions, Utkan Güngördü, Shane Sandhoefner, Alexey Kovalev
Stabilization And Control Of Majorana Bound States With Elongated Skyrmions, Utkan Güngördü, Shane Sandhoefner, Alexey Kovalev
Faculty Publications, Department of Physics and Astronomy
We show that elongated magnetic skyrmions can host Majorana bound states in a proximitycoupled twodimensional electron gas sandwiched between a chiral magnet and an swave superconductor. Our proposal requires stable skyrmions with unit topological charge, which can be realized in a wide range of multilayer magnets, and it allows quantum information transfer by using standard methods in spintronics via skyrmion motion. We also show how braiding operations can be realized in our proposal.
Spin Hall And Nernst Effects Of Weyl Magnons, Vladimir Zyuzin, Alexey Kovalev
Spin Hall And Nernst Effects Of Weyl Magnons, Vladimir Zyuzin, Alexey Kovalev
Faculty Publications, Department of Physics and Astronomy
In this paper, we present a simple model of a threedimensional insulating magnetic structure which represents a magnonic analog of the layered electronic system described by A. A. Burkov and L. Balents [Phys. Rev. Lett. 107, 127205 (2011)]. In particular, our model realizes Weyl magnons as well as surface states with a Dirac spectrum. In this model, the DzyaloshinskiiMoriya interaction is responsible for the separation of opposite Weyl points in momentum space. We calculate the intrinsic (due to the Berry curvature) transport properties of Weyl and socalled anomalous Hall effect magnons. The results are compared with fermionic analogs.
MagnetoElectric Logic Devices Using Semiconductor Channel With Large SpinOrbit Coupling (U.S. Patent Application), Dmitri E. Nikonov, Christian Binek, Xia Hong, Jonathan P. Bird, Kang L. Wang, Peter Dowben
MagnetoElectric Logic Devices Using Semiconductor Channel With Large SpinOrbit Coupling (U.S. Patent Application), Dmitri E. Nikonov, Christian Binek, Xia Hong, Jonathan P. Bird, Kang L. Wang, Peter Dowben
Faculty Publications, Department of Physics and Astronomy
Antiferromagnetic magnetoelectric spinorbit read (AFSOR) logic devices are presented. The devices include a voltagecontrolled magnetoelectric (ME) layer that switches polarization in response to an electric field from the applied voltage and a narrow channel conductor of a spinorbit coupling (SOC) material on the ME layer. One or more sources and one or more drains, each optionally formed of ferromagnetic material, are provided on the SOC material.
LaserInduced Electron Emission From Au Nanowires: A Probe For Orthogonal Polarizations, Eric R. Jones, Wayne ChengWei Huang, Gobind Basnet, Bret N. Flanders, Herman Batelaan
LaserInduced Electron Emission From Au Nanowires: A Probe For Orthogonal Polarizations, Eric R. Jones, Wayne ChengWei Huang, Gobind Basnet, Bret N. Flanders, Herman Batelaan
Faculty Publications, Department of Physics and Astronomy
Photoelectron field emission, induced by femtosecond laser pulses focused on metallic nanotips, provides spatially coherent and temporally short electron pulses. The properties of the photoelectron yield give insight into both the material properties of the nanostructure and the exciting laser focus. Ultralong nanoribbons, grown as a single crystal attached to a metallic taper, are sources of electron field emission that have not yet been characterized. In this report, photoemission from gold nanoribbon samples is studied and compared to emission from tungsten and gold tips. We observe that the emission from sharp tips generally depends on one transverse component of the ...
Phase Stability, Ordering Tendencies, And Magnetism In SinglePhase Fcc AuFe Nanoalloys, I. A. Zhuravlev, S. V. Barabash, J. M. An, K. D. Belashchenko
Phase Stability, Ordering Tendencies, And Magnetism In SinglePhase Fcc AuFe Nanoalloys, I. A. Zhuravlev, S. V. Barabash, J. M. An, K. D. Belashchenko
Faculty Publications, Department of Physics and Astronomy
Bulk AuFe alloys separate into Aubased fcc and Febased bcc phases, but L10 and L12 orderings were reported in singlephase AuFe nanoparticles. Motivated by these observations, we study the structural and ordering energetics in this alloy by combining density functional theory (DFT) calculations with effective Hamiltonian techniques: a cluster expansion with structural filters, and the configurationdependent lattice deformation model. The phase separation tendency in AuFe persists even if the fccbcc decomposition is suppressed. The relative stability of disordered bcc and fcc phases observed in nanoparticles is reproduced, but the fully ordered L10 AuFe, L12 Au3Fe, and L12 AuFe3 structures are ...
Distance Verification For Classical And Quantum Ldpc Codes, Ilya Dumer, Alexey Kovalev, Leonid P. Pryadko
Distance Verification For Classical And Quantum Ldpc Codes, Ilya Dumer, Alexey Kovalev, Leonid P. Pryadko
Faculty Publications, Department of Physics and Astronomy
The techniques of distance verification known for general linear codes are first applied to the quantum stabilizer codes. Then, these techniques are considered for classical and quantum (stabilizer) lowdensityparitycheck (LDPC) codes. New complexity bounds for distance verification with provable performance are derived using the average weight spectra of the ensembles of LDPC codes. These bounds are expressed in terms of the erasurecorrecting capacity of the corresponding ensemble. We also present a new irreduciblecluster technique that can be applied to any LDPC code and takes advantage of paritychecks’ sparsity for both the classical and quantum LDPC codes. This technique reduces complexity ...
Reversible Spin Texture In Ferroelectric Hfo2, L. L. Tao, Tula R. Paudel, Alexey Kovalev, Evgeny Tsymbal
Reversible Spin Texture In Ferroelectric Hfo2, L. L. Tao, Tula R. Paudel, Alexey Kovalev, Evgeny Tsymbal
Faculty Publications, Department of Physics and Astronomy
Spinorbit coupling effects occurring in noncentrosymmetric materials are known to be responsible for nontrivial spin configurations and a number of emergent physical phenomena. Ferroelectric materials may be especially interesting in this regard due to reversible spontaneous polarization making possible a nonvolatile electrical control of the spin degrees of freedom. Here, we explore a technologically relevant oxide material, HfO2, which has been shown to exhibit robust ferroelectricity in a noncentrosymmetric orthorhombic phase. Using theoretical modelling based on densityfunctional theory, we investigate the spindependent electronic structure of the ferroelectric HfO2 and demonstrate the appearance of chiral spin textures driven by spinorbit coupling ...
Pumping Of Magnons In A DzyaloshinskiiMoriya Ferromagnet, Alexey Kovalev, Vladimir Zyuzin, Bo Li
Pumping Of Magnons In A DzyaloshinskiiMoriya Ferromagnet, Alexey Kovalev, Vladimir Zyuzin, Bo Li
Faculty Publications, Department of Physics and Astronomy
We formulate a microscopic linear response theory of magnon pumping applicable to multiplemagnonicband uniform ferromagnets with DzyaloshinskiiMoriya interactions. From the linear response theory, we identify the extrinsic and intrinsic contributions where the latter is expressed via the Berry curvature of magnonic bands. We observe that in the presence of a timedependent magnetization DzyaloshinskiiMoriya interactions can act as fictitious electric fields acting on magnons. We study various current responses to this fictitious field and analyze the role of Berry curvature. In particular, we obtain an analog of the Halllike response in systems with nontrivial Berry curvature of magnon bands. After identifying ...
TwoColor Multiphoton Emission From Nanotips, Wayne ChengWei Huang, Maria Becker, Joshua Beck, Herman Batelaan
TwoColor Multiphoton Emission From Nanotips, Wayne ChengWei Huang, Maria Becker, Joshua Beck, Herman Batelaan
Faculty Publications, Department of Physics and Astronomy
Twocolor multiphoton emission from polycrystalline tungsten nanotips has been demonstrated using twocolor laser fields. The twocolor photoemission is assisted by a threephoton multicolor quantum channel, which leads to a twofold increase in quantum efficiency. Weakfield control of two color multiphoton emission was achieved by changing the efficiency of the quantum channel with pulse delay. The result of this study complements twocolor tunneling photoemission in strong fields, and has potential applications for nanowirebased photonic devices. Moreover, the demonstrated twocolor multiphoton emission may be important for realizing ultrafast spinpolarized electron sources via optically injected spin current.
Structure Evolution And Multiferroic Properties In Cobalt Doped Bi_{4}Ndti_{3}Fe_{1X}Co_{X}O_{15} Bi_{3}Ndti_{2}Fe_{1X}Coxo_{12Δ} Intergrowth Aurivillius Compounds, D. L. Zhang, W. C. Huang, Z. W. Chen, W. B. Zhao, L. Feng, M. Li, Y. W. Yin, S. N. Dong, X. G. Li
Structure Evolution And Multiferroic Properties In Cobalt Doped Bi4Ndti3Fe1XCoXO15 Bi3Ndti2Fe1XCoxo12Δ Intergrowth Aurivillius Compounds, D. L. Zhang, W. C. Huang, Z. W. Chen, W. B. Zhao, L. Feng, M. Li, Y. W. Yin, S. N. Dong, X. G. Li
Faculty Publications, Department of Physics and Astronomy
Here, we report the structure evolution, magnetic and ferroelectric properties in Codoped 4 and 3layered intergrowth Aurivillius compounds Bi_{4}NdTi_{3}Fe_{1x} Co_{x}O_{15}Bi_{3}NdTi_{2}Fe_{1x}Co_{x}O_{12δ}. The compounds suffer a structure evolution from the parent 4layered phase (Bi_{4}NdTi_{3}FeO_{15}) to 3layered phase (Bi_{3}NdTi_{2}CoO_{12δ}) with increasing cobalt doping level from 0 to 1. Meanwhile the remanent magnetization and polarization show opposite variation tendencies against the doping level, and the sample with x = 0.3 has the ...
Dualism Between Optical And Difference Parametric Amplification, Wayne ChengWei Huang, Herman Batelaan
Dualism Between Optical And Difference Parametric Amplification, Wayne ChengWei Huang, Herman Batelaan
Faculty Publications, Department of Physics and Astronomy
Breaking the symmetry in a coupled wave system can result in unusual amplification behavior. In the case of difference parametric amplification the resonant pump frequency is equal to the difference, instead of the sum, frequency of the normal modes. We show that sign reversal in the symmetry relation of parametric coupling give rise to difference parametric amplification as a dual of optical parametric amplification. For optical systems, our result can potentially be used for efficient XUV amplification.
Magnon Spin Nernst Effect In Antiferromagnets, Vladimir Zyuzin, Alexey Kovalev
Magnon Spin Nernst Effect In Antiferromagnets, Vladimir Zyuzin, Alexey Kovalev
Faculty Publications, Department of Physics and Astronomy
We predict that a temperature gradient can induce a magnonmediated spin Hall response in an antiferromagnet with nontrivial magnon Berry curvature. We develop a linear response theory which gives a general condition for a Hall current to be well defined, even when the thermal Hall response is forbidden by symmetry. We apply our theory to a honeycomb lattice antiferromagnet and discuss a role of magnon edge states in a finite geometry.
Theory Of Spin Loss At Metallic Interfaces, Kirill D. Belashchenko, Alexey Kovalev, Mark Van Schilfgaarde
Theory Of Spin Loss At Metallic Interfaces, Kirill D. Belashchenko, Alexey Kovalev, Mark Van Schilfgaarde
Faculty Publications, Department of Physics and Astronomy
Interfacial spinflip scattering plays an important role in magnetoelectronic devices. Spin loss at metallic interfaces is usually quantified by matching the magnetoresistance data for multilayers to the ValetFert model, while treating each interface as a fictitious bulk layer whose thickness is δ times the spindiffusion length. By employing the properly generalized circuit theory and the scattering matrix approaches, we derive the relation of the parameter δ to the spinflip transmission and reflection probabilities at an individual interface. It is found that δ is proportional to the square root of the probability of spinflip scattering. We calculate the spinflip scattering probabilities ...