Visualization of Dynamic Vortex Structures in Magnetic Films with Uniaxial Anisotropy (Micromagnetic Simulation)

Three-dimensional computer simulation of dynamic processes in a moving domain boundary separating domains in a soft magnetic uniaxial film with planar anisotropy is performed by numerical solution of Landau-Lifshitz-Gilbert equations. The developed visualization methods are used to establish the connection between the motion of surface vortices and antivortices, singular (Bloch) points, and core lines of intrafilm vortex structures. A relation between the character of magnetization dynamics and the film thickness is found. The analytical models of spatial vortex structures for imitation of topological properties of the structures observed in micromagnetic simulation are constructed.     

Effects of the Gravitational Interaction of a Scalar Field and Magnetic and Electric Vortex Fields

Russian Physics Journal - The combined action of self-gravitating magnetic and electric vortex fields and a self-gravitating scalar field is considered. The properties of wormholes formed as a...     

Peculiarities of the Gravitational Interaction of Electrical and Magnetic Vortex Fields with Nonlinear Vortex-Free Fields

Russian Physics Journal - Within the framework of GRT, the properties of the gravitational interaction of magnetic and electric vortex fields with self-gravitating nonvortex fields are...     

Exploitable Magnetic Anisotropy of Magnetic CrBr3 Monolayer

JETP Letters - We investigated the influence of Li and F adsorption on the ferromagnetism and magnetic anisotropy energy of CrBr3 monolayer based on the first-principles calculations. It is...     

Optical Anisotropy of Biaxial Magnetic Crystals

The two–dimensional orthogonal representation of electromagnetic waves in crystals is developed. Simple expressions determining the directions of optical axes and dependence of group and phase velocities and polarization vectors on the direction, in the general case, of triclinic crystals of magnetic dielectrics are obtained. A solution of the Maxwell equations in the form of two isonormal harmonic waves is found to be directly related to the exponential, two–dimensional spinor, and three–dimensional tensor representations.     

Interaction of a Plasma Beam with a Transverse Magnetic Barrier

The interaction of an energetic He plasma beam with a quasi step-like transverse magnetic barrier is reported. When the rate of flow of momentum in the incident beam is less than the pressure of the magnetic field, a collisionless electrostatic shock is observed to form in front of the barrier as a result of the drastic compression of the plasma. The initially cold plasma is substantially thermalized by the shock and the electron density is increased by a factor of four. In the opposite limit the plasma penetrates the barrier in a flute-like manner.     

Interaction of a charged extended body with Magnetic field

It is shown that the conventional energy expressions need modification for the interaction of a charged extended body with a magnetic field. It is also shown that the correction term arises as a result of the rotation of the charged extended body about its centre of mass in a magnetic field. This can provide us with an additional source of energy that can be tapped with a suitable energy conversion device.     

Magnetic Vortex Tubes in Astrophysics

The viscous forces on electrons and ions in a differentially rotating plasma drive an azimuthal current density j?, with axial magnetic field Bz which is shown to be proportional to plasma vorticity. Field strengths in agreement with those observed for both stars and galaxies are obtained, assuming that reactive forces prevent radial drifts of electrons or ions. Hierarchical vorticity is required in order to reconcile the small-scale length required for field changes with the large-scale length of observed fields. A vortex tube with magnetic field (magnetic vortex tube-MVT) becomes the basic entity for the origin of magnetic fields. Twisting of field lines by differential rotation causes (1?,Bz,) ?(jz, B?,). When jzB?, > j?, Bz the MVT suffers magnetic pinch, and the axial current in the pinch flows through a cylindrical sheath with a radial electric field due to plasma polarization. An instability of drift velocity denudes a length R of the current channel of free charges, and the inductively maintained current then requires a displacement current in R and hence a growing axial electric field Ez, Ez is limited by transfer of the energy in B?, to Ez, and thereafter the energy oscillates between the fields. On the stellar scale, evidence for polar MVT's comes from young stars with bipolar outflows of gas and jets. It is argued that end-on viewing of polar MVT's accounts for the kilogauss fields of Ap stars and the 1-100-MG fields of magnetic white dwarfs.     

Capabilities of Magnetic Pseudoresonance in Studies of Thin Ferromagnetic Films with Uniaxial Magnetic Anisotropy

Technical Physics - Possibilities of magnetic pseudoresonance (a non-resonance peak of magnetic susceptibility) were studied and compared with the ferromagnetic resonance (FMR) in measuring the...     

Features of a Domain Structure with Asymmetric Magnetic Heterogeneity in Film Materials with High Anisotropy

The theory of magnetic domain ordering in magnetic film materials with asymmetric magnetic heterogeneity is considered, with allowance for changes in the magnetostatic energy and that of the anisotropy of a curved domain boundary. The effect the parameters that determine changes in the energy of the magnetostatic interaction of the domain structure and the energy of the anisotropy of the curved domain boundary have on the shape and value of domain boundary bending is analyzed.     

Preparation of Fe/Pt Films with Perpendicular Magnetic Anisotropy

We have investigated the microstructures and magnetic properties of L1₀ ordered equi-atomic FePt thin films prepared by ion beam sputtering and subsequent annealing. It is observed from X-ray reflectivity and X-ray diffraction measurements that the mixing at Fe/Pt interfaces starts to occur with annealing and leading to the FePt alloy phase formation. The rapid increase in the coercivity values above 275°C, obtained from vibrating sample magnetometer (VSM) measurements, confirms the formation of the ordered L1₀ FCT FePt phase.     

Magnetic Anisotropy and Super-Sensitive Stress-Magnetoimpedance in Microwires with Positive Magnetostriction

Physics of the Solid State - In glass-coated Co71Fe5B11Si10Cr3 amorphous ferromagnetic microwires subjected to current annealing, a record sensitivity of the magnetoimpedance (MI) to mechanical...     

Heat-Treatment Induced Magnetic Anisotropy of GaMnSb Films

Conditions and mechanisms of controlled variation of the magnetic anisotropy of GaMnSb films containing magnetic MnSb nanoinclusions by means of heat treatment have been determined. For this purpose, the temperature and magnetic-field dependences of the magnetic moments of samples before and after thermal annealing were measured using a SQUID magnetometer. It is established that the heat treatment of GaMnSb films leads to a significant increase in the values of characteristics determined by the magnetic anisotropy, including the growth of blocking temperature (from 95 to 390 K) and the magnetic anisotropy field (from 330 to 630 Oe). Results of transmission electron microscopy investigation indicate that a change in the magnetic anisotropy of GaMnSb films as a result of their thermal annealing can be related to a transition of the crystalline structure of magnetic MnSb nanoinclusions from hexagonal (space group P6₂/mmc) to cubic (space group F-43m).     

Viscous Interaction Between a Vortex Tube and a Rotating Spherical Particle

The transient advection of a cylindrical vortex tube in a viscous incompressible flow field and its interaction with a rotating/spinning spherical particle has been investigated numerically at Reynolds numbers in the range of 20≤ Re≤200 for angular velocities of 0≤Ω≤0.5. The effects of vortex parameters such as size, circulation strength and initial position relative to the particle, on the temporal behavior of the lift and drag forces are studied. Vortex‐sphere interactions bring about major changes in the flow field particularly when coupled with particle rotation. It is observed that the forces acting on the particle are significantly influenced during the time that the vortex core is in the vicinity of the particle. The extent of these local changes are about ±30% in the drag coefficient and about ±200% in the lift coefficient as compared to flow over a rotating solid sphere with no vortex interaction. It is also found that a vortex with core radius between one and two particle diameters creates the strongest temporal variations in the lift and drag coefficients. Furthermore, maximum lift variations occur for the vortex‐particle head on collision, while a vortex with an offset distance of about one diameter from the principal flow axis generates the maximum drag variations.     

Anisotropy of Isobaric Instability in a Partially Ionized Plasma in a Magnetic Field

Bulletin of the Lebedev Physics Institute - Linear equations describing the dynamics of small perturbations in partially ionized heat-releasing plasma in an external magnetic field with an...     

Coulomb Interaction in Quantum Dot with a Precessing Magnetic Field

We study electronic transport through a quantum dot （QD） with a precessing magnetic field. By using the Keldysh nonequilibrium Green function method, formulas of local density of states （LDOS） and conductance of QD are derived self-consistently. It shows that the LDOS and conductance have obvious changes with the Coulomb blockade interaction. The intensity and angle of the magnetic field or temperatures, which reflect the mesoscopic structure of the QD are derived. The superiority of this device is that the QD can be controlled easily by the magnetic field, so it is valuable to apply in generating, manipulating and probing spin state.