arXiv subjects

Ya. B. Bazaliy

Publications and source records attributed to Ya. B. Bazaliy.

At least 19 recordsLinked to original sources

arXiv2026

Electric excitation of spin resonance in altermagnetic and antiferromagnetic conductors

We predict electric-dipole spin resonance (EDSR) in altermagnetic conductors: in a magnetic field ${\mathbf H}_\perp$, perpendicular to the magnetization axis, an AC electric field will induce a \textit{spin} resonance peak above the lower threshold frequency $ω_- = 2H_\perp$. In sufficiently clean samples, this peak shall be clearly visible on the background of ohmic absorption. EDSR can thus serve as a diagnostic of altermagnetism in conducting materials and as a means to distinguish it from higher-symmetry antiferromagnetic order.

cond-mat.str-el↗

arXiv2026

Classical diamagnetism at large magnetic fields

Many textbooks discuss the diamagnetic response of a ``classical atom'' to a small, adiabatically slowly applied magnetic field. Here we solve this problem for an arbitrarily large field. This gives a more satisfying justification for the assumptions made in the small field regime, explains the role of adiabaticity, identifies the symmetries persisting at large fields, and illustrates the range of applicability of the Larmor's theorem.

physics.ed-ph↗

arXiv2025

Numeric simulations build a bridge from a two-slit experiment to the basics of X-ray diffraction and coherent optics

Numeric simulations based on the Huygens-Fresnel method allow one to develop intuition about the behavior of coherent light in diffraction and interference experiments. They give an opportunity to numerically observe and appreciate a number important phenomena, while avoiding the need to deal with the intricacies of their analytic descriptions. In an introductory teaching lab, they help to build a matrix of ideas, into which many optical demonstration experiments fall nicely and to the benefit of a student.

physics.optics↗

arXiv2024

Alternating current Hanle effect as poor man's paramagnetic resonance

It is shown that in spin injection experiments the interplay between external magnetic field and alternating current can be observed already on a single ferromagnet/normal metal interface. The interface resistance is predicted to exhibit prominent features whenever the frequency of spin precession in the applied field becomes equal to the frequency of the driving current. Using these features, material-specific g-factors of electrons in normal metals can be measured with less effort, albeit also with less precision.

cond-mat.mtrl-sci↗

arXiv2023

Spin transfer exchange torque in ferromagnet/ferromagnet structures made of half metals with large exchange gaps

Spin torques in magnetic multilayers are produced by spin polarization $P$ of ferromagnetic (F) layers, and increase with growing $P$. The latter, however, cannot exceed the $P=1$ value found in half metals. We study the $P=1$ case to find what other parameters still influence spin torques in this extreme limit. It is found that the ratio of exchange gap to Fermi energy strongly affects the properties of the torque. For large values of the gap the magnitude of exchange spin torque exhibits a sharp peak at very small misalignment angles between magnetizations. This behavior is found to be linked to a transition between Ohmic and tunneling transport regimes through the F/F boundary.

cond-mat.mtrl-sci↗

arXiv2020

Understanding spintronics in F/N/F structures through a mechanical analogy

A mechanical equivalent system is introduced to mimic the behavior of multilayer structures with diffusive spin transport. The analogy allows one to use existing mechanical intuition to predict the influence of various parameters on spin torques and spin-dependent magnetoresistance. In particular, it provides an understanding of the sign-changing behavior of spin torque in asymmetric F/N/F spin valves. It further helps to uncover the physical reason behind the singular behavior of spin magnetoresistance in devices with ultra-thin N-layers.

cond-mat.mes-hall↗

arXiv2019

Closed-loop electric currents and non-local resistance measurements with wide F/I/N tunnel contacts

Lateral spin valves are used to generate and characterize pure spin currents. Non-local voltage measured in such structures provides information about spin polarization and spin decay rates. For wide high-transparency F/N contacts it was shown that the Johnson-Silsbee non-local effect is substantially enriched by closed-loop electric currents driven by local spin injection in the electrically dangling part of the valve. For valves with low-transparency F/I/N tunnel contacts such circular currents are strongly suppressed, yet we show that the voltage modifications persist, may be significant, and must be accounted for in the data analysis.

cond-mat.mes-hall↗

arXiv2018

Reciprocity in diffusive spin-current circuits

Similarly to their purely electric counterparts, spintronic circuits may be presented as networks of lumped elements. Due to interplay between spin and charge currents, each element is described by a matrix conductance. We establish reciprocity relations between the entries of the conductance matrix of a multi-terminal linear device, comprising normal metallic and strong ferromagnetic elements with spin-inactive interfaces between them. In particular, reciprocity equates the spin transmissions through a two-terminal element in the opposite directions. When applied to "geometric spin ratchets", reciprocity shows that certain effects, announced for such devices, are, in fact, impossible. Finally, we discuss the relation between our work and the spintronic circuit theory formalism.

cond-mat.mes-hall↗

arXiv2017

Local injection of pure spin current generates electric current vortices

We show that local injection of pure spin current into an electrically disconnected ferromagnetic - normal-metal sandwich induces electric currents, that run along closed loops inside the device, and are powered by the source of the spin injection. Such electric currents may significantly modify voltage distribution in spin-injection devices and induce long-range tails of spin accumulation.

cond-mat.mes-hall↗

arXiv2015

Phase diagram and optimal switching induced by spin Hall effect in a perpendicular magnetic layer

In a ferromagnet/heavy-metal bilayer device with strong spin Hall effect an in-plane current excites magnetic dynamics through spin torque. We analyze bilayers with perpendicular magnetization and calculate three-dimensional phase diagrams describing switching by external magnetic field at a fixed current. We then concentrate on the case of a field applied in the plane formed by the film normal and the current direction. Here we analytically study the evolution of both the conventional "up"/"down" magnetic equilibria and the additional equilibria created by the spin torque. Expressions for the stability regions of all equilibria are derived, and the nature of switching at each critical boundary is discussed. The qualitative picture obtained this way predicts complex hysteresis patterns that should occur in bilayers. By analyzing the phase portraits of the system we show that when the spin torque induced equilibrium exists, switching between "up" and "down" states proceeds through it as an intermediate state. Using numeric simulations we analyze the switching time and compare it to that of a conventional spin torque device with collinear magnetizations of the polarizer and the free layer.

cond-mat.mes-hall↗

arXiv2011

Planar approximation for the frequencies of spin transfer oscillators

A large class of spin transfer oscillators use the free layer with a strong easy plane anisotropy, which forces its magnetization to move close to the plane. We show that in this situation the effective planar approximation provides a fast and accurate way of calculating the oscillator frequency.

cond-mat.mtrl-sci↗

arXiv2011

Planar approximation for spin transfer systems with application to tilted polarizer devices

Planar spin-transfer devices with dominating easy-plane anisotropy can be described by an effective one-dimensional equation for the in-plane angle. Such a description provides an intuitive qualitative understanding of the magnetic dynamics. We give a detailed derivation of the effective planar equation and use it to describe magnetic switching in devices with tilted polarizer.

cond-mat.mtrl-sci↗

arXiv2011

Ballistic (precessional) contribution to the conventional magnetic switching

We consider a magnetic moment with an easy axis anisotropy energy, switched by an external field applied along this axis. Additional small, time-independent bias field is applied perpendicular to the axis. It is found that the magnet's switching time is a non-monotonic function of the rate at which the field is swept from "up" to "down". Switching time exhibits a minimum at a particular optimal sweep time. This unusual behavior is explained by the admixture of a ballistic (precessional) rotation of the moment caused by the perpendicular bias field in the presence of a variable switching field. We derive analytic expressions for the optimal switching time, and for the entire dependence of the switching time on the field sweep time. The existence of the optimal field sweep time has important implications for the optimization of magnetic memory devices.

cond-mat.mtrl-sci↗

arXiv2011

Analytic treatment of the precessional (ballistic) contribution to the conventional magnetic switching

We consider a switching of the magnetic moment with an easy axis anisotropy from an "up" to a "down" direction under the influence of an external magnetic field. The driving field is applied parallel to the easy axis and is continuously swept from a positive to a negative value. In addition, a small constant perpendicular bias field is present. It is shown that while the driving field switches the moment in a conventional way, the perpendicular field creates an admixture of the precessional (ballistic) switching that speeds up the switching process. Precessional contribution produces a non-monotonic dependence of the switching time on the field sweep time with a minimum at a particular sweep time value. We derive an analytic expressions for the optimal point, and for the entire dependence of the switching time on the field sweep time. Our approximation is valid in a wide parameter range and can be used to engineer and optimize of the magnetic memory devices.

cond-mat.mtrl-sci↗

arXiv2009

Anomalous stabilization in a spin-transfer system at high spin polarization

Switching diagrams of nanoscale ferromagnets driven by a spin-transfer torque are studied in the macrospin approximation. We consider a disk-shaped free layer with in-plane easy axis and external magnetic field directed in-plane at 90 degrees to that axis. It is shown that this configuration is sensitive to the angular dependence of the spin-transfer efficiency factor and can be used to experimentally distinguish between different forms of $g(θ)$, in particular between the original Slonczewski form and the constant $g$ approximation. The difference in switching diagrams is especially pronounced at large spin polarizations, with the Slonczewski case exhibiting an anomalous region.

cond-mat.mtrl-sci↗

arXiv2009

Invariant form of spin-transfer switching condition

We derive an invariant form of the current-induced switching condition in spin-transfer devices and show that for energy minima and maxima the "switching ability" of the current is determined by the spin torque divergence. In contrast, energy saddle points are normally stabilized by current-induced merging with other equilibria. Our approach provides new predictions for several experimental setups and shows the limitations of some frequently used approximations.

cond-mat.mtrl-sci↗

arXiv2008

Dynamics of a vortex domain wall in a magnetic nanostrip: an application of the collective coordinate approach

The motion of a vortex domain wall in a ferromagnetic strip of submicron width under the influence of an external magnetic field exhibits three distinct dynamical regimes. In a viscous regime at low fields the wall moves rigidly with a velocity proportional to the field. Above a critical field the viscous motion breaks down giving way to oscillations accompanied by a slow drift of the wall. At still higher fields the drift velocity starts rising with the field again but with a much lower mobility dv/dH than in the viscous regime. To describe the dynamics of the wall we use the method of collective coordinates that focuses on soft modes of the system. By retaining two soft modes, parametrized by the coordinates of the vortex core, we obtain a simple description of the wall dynamics at low and intermediate applied fields that describes both the viscous and oscillatory regimes below and above the breakdown. The calculated dynamics agrees well with micromagnetic simulations at low and intermediate values of the driving field. In higher fields, additional modes become soft and the two-mode approximation is no longer sufficient. We explain some of the significant features of vortex domain wall motion in high fields through the inclusion of additional modes associated with the half-antivortices on the strip edge.

cond-mat.mtrl-sci↗

arXiv2008

Dynamics of domain walls in magnetic nanostrips

We express dynamics of domain walls in ferromagnetic nanowires in terms of collective coordinates generalizing Thiele's steady-state results. For weak external perturbations the dynamics is dominated by a few soft modes. The general approach is illustrated on the example of a vortex wall relevant to recent experiments with flat nanowires. A two-mode approximation gives a quantitatively accurate description of both the steady viscous motion of the wall in weak magnetic fields and its oscillatory behavior in moderately high fields above the Walker breakdown.

cond-mat.mtrl-sci↗