O. P. Polyakov

Chaos and self-organization in an open nonconservative system of two plane coplanar magnetized bodies with moments of inertia

Numerical analysis is used to study the nonlinear oscillation processes in an open nonconservative system of two plane coplanar magnetized bodies with moments of inertia. Bifurcation diagrams that illustrate different dynamic regimes of the system in an oscillating magnetic field, as well as the possibility of transitions from one regime to another due to variations in the parameters of the external action, are obtained. It is established that, for the regimes corresponding to infinite phase trajectories, in the general case, an asymmetry occurs in the choice of the rotation direction of the magnetized bodies.

Control of chaotic and deterministic magnetization dynamics regimes by means of sample shape varying

Effect of demagnetization field on chaotic and deterministic nonlinear magnetization dynamics regimes formation in the presence of oscillating and constant external magnetic fields is studied using the Landau–Lifshitz–Gilbert approach. The uniformly magnetized sample is considered to be an axially symmetric particle described by demagnetization factors and to have uniaxial crystallographic anisotropy formed some angle with an applied field direction. The equations of magnetic moment motion are considered to be the synergetic equations and the system behavior is examined on the phase plane. It is investigated as to how the change in particle shape and its orientation with respect to the external field (system’s configuration) can cause the transition between chaos and regular magnetization dynamics. Moreover, the way to completely suppress chaotic dynamics of magnetic moments in such sample is proposed. To produce a regular study, all results are presented in the form of bifurcation diagrams for all suffic...

Fractal structure of the phase equilibrium curve of a system of two oscillating magnetic moments

The fractal structure of the phase equilibrium curve of a system of two interacting magnetic moments in the presence of a uniform low-frequency bias magnetic field is found by numerical methods. It is established that as frequency increases, the phase equilibrium curve becomes smooth. For that case an exact solution of the dynamical equations is found which gives a good description of the numerical results.

Tuning an Atomic Switch on a Surface with Electric and Magnetic Fields.

Controllable switching an adatom position and its magnetization could lead to a single-atom memory. Our theoretical studies show that switching adatom between different surface sites by the quantum tunneling, discovered in several experiments, can be controlled by an external electric field. Switching a single spin by magnetic fields is found to be strongly site-dependent on a surface. This could enable to control a spin-dynamics of adatom.

Complex domain structure in a magnetic film with oblique anisotropy

Analytical formulas have been derived to calculate the distortion of the stripe domain structure in a ferromagnetic film under the action of a bubble domain formed in this film. On the basis of the formulas obtained, an experimentally obtained domain configuration has been calculated. The results of the calculation coincide with the observation data within the experimental error.

Impact of surface strain on the spin dynamics of deposited Co nanowires

Tailoring the magnetic properties at atomic-scale is essential in the engineering of modern spintronics devices. One of the main concerns in the novel nanostructured materials design is the decrease of the paid energy in the way of functioning, but allowing to switch between different magnetic states with a relative low-cost energy at the same time. Magnetic anisotropy (MA) energy defines the stability of a spin in the preferred direction and is a fundamental variable in magnetization switching processes. Transition-metal wires are known to develop large, stable spin and orbital magnetic moments together with MA energies that are orders of magnitude larger than in the corresponding solids. Different ways of controlling the MA have been exploited such as alloying, surface charging, and external electrical fields. Here we investigate from a first-principle approach together with dynamic calculations, the surface strain driven mechanism to tune the magnetic properties of deposited nanowires. We consider as a...

Electronic and magnetic properties at the edges of nanostructures in an electric field: ab initio study

State of the art ab initio calculations of the electronic and magnetic properties at the edges of magnetic nanostructures in an external electric field are presented in this paper. Our results for the Fe stripes on Fe(0 0 1) reveal the existence of spin-polarized edge states. A spatially inhomogeneous electronic structure is found at the edge. We demonstrate that the spin-dependent screening density varies greatly at the atomic scale. Tuning of the spin-polarization by the external electric field is demonstrated.

Frequency characteristics of the one-layer anisotropic magnetoresistive sensitive nanoelements

The high-frequency characteristics of the one-layer anisotropic magnetoresistive strip—the magnetosensitive nanoelement of the magnetic field sensor—were analyzed on the basis of the Landau-Livshits-Hilbert equation. The results of this study were shown to coincide completely with the linear microwave theory. The strip frequency characteristics were analyzed for low-anisotropy and high-anisotropy FeNiCo ferromagnetic films of various thickness, strip width, easy magnetization direction, and fixed external magnetic field.

A Permanent Spherical Magnet with Inhomogeneous Magnetization

Inhomogeneously distributed magnetization that induces a strong magnetic field in a predetermined local area is established in finite permanent magnets. The maximum possible magnetic induction in the vicinity of a magnet’s center is found analytically for a perfect spherical magnet.

Analytical theory of magnetization of fine particles in external alternating field

Nonlinear dynamics of a spherical magnetic particle and an ensemble of such particles in an external oscillating magnetic field have been studied analytically and numerically in terms of the Landau-Lifshitz-Gilbert equation. The exact analytical formulas have been obtained allowing the calculation of the projections of the mean-in-time magnetization of the system on the frequency of an external field and initial orientation of magnetic moments. The behavior of the system in the limiting cases of low and high frequencies has been considered. The analytical solutions obtained agree well with the direct numerical calculations of the Landau-Lifshitz-Gilbert equation. The analytical theory of the effect of the nonlinear dynamic polarization has been developed, and its applicability for designing devises of magnetic memory has been discussed.