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Articles 1 - 9 of 9

Full-Text Articles in Physics

Magnon Spin Nernst Effect In Antiferromagnets, Vladimir Zyuzin, Alexey Kovalev Nov 2016

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 magnon-mediated 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 Nov 2016

Theory Of Spin Loss At Metallic Interfaces, Kirill D. Belashchenko, Alexey Kovalev, Mark Van Schilfgaarde

Faculty Publications, Department of Physics and Astronomy

Interfacial spin-flip 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 Valet-Fert model, while treating each interface as a fictitious bulk layer whose thickness is δ times the spin-diffusion length. By employing the properly generalized circuit theory and the scattering matrix approaches, we derive the relation of the parameter δ to the spin-flip transmission and reflection probabilities at an individual interface. It is found that δ is proportional to the square root of the probability of spin-flip scattering. We calculate the spin-flip scattering probabilities ...


Magnetoelectric Domain Wall Dynamics And Its Implications For Magnetoelectric Memory, Kirill D. Belashchenko, Oleg Tchernyshyov, Alexey Kovalev, Oleg A. Tretiakov Jan 2016

Magnetoelectric Domain Wall Dynamics And Its Implications For Magnetoelectric Memory, Kirill D. Belashchenko, Oleg Tchernyshyov, Alexey Kovalev, Oleg A. Tretiakov

Faculty Publications, Department of Physics and Astronomy

Domain wall dynamics in a magnetoelectric antiferromagnet is analyzed, and its implications for magnetoelectric memory applications are discussed. Cr2O3 is used in the estimates of the materials parameters. It is found that the domain wall mobility has a maximum as a function of the electric field due to the gyrotropic coupling induced by it. In Cr2O3, the maximal mobility of 0.1 m/(s Oe) is reached at E = 0.06 V/nm. Fields of this order may be too weak to overcome the intrinsic depinning field, which is estimated for B-doped Cr2 ...


Eikonal Perturbation Theory In Photoionization, F. Cajiao Vélez, Katarzyna Krajewska, J. Z. Kamiński Jan 2016

Eikonal Perturbation Theory In Photoionization, F. Cajiao Vélez, Katarzyna Krajewska, J. Z. Kamiński

Faculty Publications, Department of Physics and Astronomy

The eikonal perturbation theory is formulated and applied to photoionization by strong laser pulses. A special emphasis is put on the first order approximation with respect to the binding potential, which is known as the generalized eikonal approximation [2015 Phys. Rev. A 91 053417]. The ordinary eikonal approximation and its domain of applicability is derived from the generalized eikonal approximation. While the former approach is singular for the electron trajectories which return to the potential center, the generalized eikonal avoids this problem. This property makes it a promising tool for further investigations of rescattering and high-order harmonic generation processes.


Theory Of Magnon Motive Force In Chiral Ferromagnets, Utkan Güngördü, Alexey Kovalev Jan 2016

Theory Of Magnon Motive Force In Chiral Ferromagnets, Utkan Güngördü, Alexey Kovalev

Faculty Publications, Department of Physics and Astronomy

We predict that magnon motive force can lead to temperature dependent, nonlinear chiral damping in both conducting and insulating ferromagnets. We estimate that this damping can significantly influence the motion of skyrmions and domain walls at finite temperatures. We also find that in systems with low Gilbert damping moving chiral magnetic textures and resulting magnon motive forces can induce large spin and energy currents in the transverse direction.


Stability Of Skyrmion Lattices And Symmetries Of Quasi-Two-Dimensional Chiral Magnets, Utkan Güngördü, Rabindra Nepal, Oleg A. Tretiakov, Kirill D. Belashchenko, Alexey Kovalev Jan 2016

Stability Of Skyrmion Lattices And Symmetries Of Quasi-Two-Dimensional Chiral Magnets, Utkan Güngördü, Rabindra Nepal, Oleg A. Tretiakov, Kirill D. Belashchenko, Alexey Kovalev

Faculty Publications, Department of Physics and Astronomy

Recently there has been substantial interest in realizations of skyrmions, in particular in quasi-two-dimensional (2D) systems due to increased stability resulting from reduced dimensionality. A stable skyrmion, representing the smallest realizable magnetic texture, could be an ideal element for ultradense magnetic memories. Here we use the most general form of the quasi-2D free energy with Dzyaloshinskii-Moriya interactions constructed from general symmetry considerations reflecting the underlying system. We predict that the skyrmion phase is robust and it is present even when the system lacks the in-plane rotational symmetry. In fact, the lowered symmetry leads to increased stability of vortex-antivortex lattices with ...


Spin Torque And Nernst Effects In Dzyaloshinskii-Moriya Ferromagnets, Alexey Kovalev, Vladimir Zyuzin Jan 2016

Spin Torque And Nernst Effects In Dzyaloshinskii-Moriya Ferromagnets, Alexey Kovalev, Vladimir Zyuzin

Faculty Publications, Department of Physics and Astronomy

We predict that a temperature gradient can induce a magnon-mediated intrinsic torque in systems with a nontrivial magnon Berry curvature. With the help of a microscopic linear response theory of nonequilibrium magnon-mediated torques and spin currents we identify the interband and intraband components that manifest in ferromagnets with Dzyaloshinskii-Moriya interactions and magnetic textures. To illustrate and assess the importance of such effects, we apply the linear response theory to the magnon-mediated spin Nernst and torque responses in a kagome lattice ferromagnet.


Measurement Of The Differential Cross Section And Charge Asymmetry For Inclusive Pp → W± + X Production At √S = 8 Tev, Ekaterina Avdeeva, Rachel Bartek, Kenneth A. Bloom, Suvadeep Bose, Daniel R. Claes, Aaron Dominguez, Caleb Fangmeier, Rebeca Gonzalez Suarez, Rami Kamalieddin, Daniel Knowlton, Ilya Kravchenko, Jose Monroy, F. Meier, F. Ratnikov, J. E. Siado, Gregory Snow, B. Stieger, Cms Collaboration Jan 2016

Measurement Of The Differential Cross Section And Charge Asymmetry For Inclusive Pp → W± + X Production At √S = 8 Tev, Ekaterina Avdeeva, Rachel Bartek, Kenneth A. Bloom, Suvadeep Bose, Daniel R. Claes, Aaron Dominguez, Caleb Fangmeier, Rebeca Gonzalez Suarez, Rami Kamalieddin, Daniel Knowlton, Ilya Kravchenko, Jose Monroy, F. Meier, F. Ratnikov, J. E. Siado, Gregory Snow, B. Stieger, Cms Collaboration

Faculty Publications, Department of Physics and Astronomy

The differential cross section and charge asymmetry for inclusive pp → W± + Xμ±ν + X production at √s = 8 TeV are measured as a function of muon pseudorapidity. The data sample corresponds to an integrated luminosity of 18.8 fb−1 recorded with the CMS detector at the LHC. These results provide important constraints on the parton distribution functions of the proton in the range of the Bjorken scaling variable x from 10−3 to 10−1.


Momentum Exchange In The Electron Double-Slit Experiment, Herman Batelaan, Eric Jones, Wayne Cheng-Wei Huang, Roger Bach Jan 2016

Momentum Exchange In The Electron Double-Slit Experiment, Herman Batelaan, Eric Jones, Wayne Cheng-Wei Huang, Roger Bach

Faculty Publications, Department of Physics and Astronomy

We provide support for the claim that momentum is conserved for individual events in the electron double slit experiment. The natural consequence is that a physical mechanism is responsible for this momentum exchange, but that even if the fundamental mechanism is known for electron crystal diffraction and the Kapitza–Dirac effect, it is unknown for electron diffraction from nano-fabricated double slits. Work towards a proposed explanation in terms of particle trajectories affected by a vacuum field is discussed. The contentious use of trajectories is discussed within the context of oil droplet analogues of double slit diffraction.