Yu. I. Dzhezherya

Magnetic Ordering in Granular System

The conditions of the formation of different magnetic structures with ferromagnetic (FM) and antiferromagnetic (AFM) ordering in granular materials containing a subsystem of ferromagnetic granules are considered within the phenomenological approach. It is supposed that the magnetostatic field and the exchange interaction between conduction electrons and magnetic ions are responsible for the formation of magnetic structure.

Features of the motion of a 180° domain boundary in a thin ferromagnetic film with defects

For a thin ferromagnetic film, the braking process of a 180° domain boundary in a field of randomly distributed point defects is studied using perturbation theory. It is established that, for low velocities, the motion of the boundary is nonsteady-state. It is shown that the critical velocity of steady-state motion depends substantially on film thickness and the defect concentration.

Energy dissipation of a 180° domain wall in a defect field. Influence of film thickness

An effective equation of motion for a 180° domain wall, taking account of energy losses due to the excitation of flexural waves of the wall when it interacts with point defects, is derived for a ferromagnetic film of arbitrary thickness. The domain wall is studied in the potential well produced by a nonuniform magnetic field. The influence of defects on the motion of a wall with constant velocity and small forced oscillations of the wall are investigated on the basis of exact particular solutions of the equation derived.

Influence of the domain structure in a magnetizing field on the high-frequency susceptibility of a ferromagnet

The high-frequency properties of a biaxial domain-containing bulk ferromagnet in an external magnetic field with a modulated amplitude are investigated on the basis of the Landau-Lifshitz equations. The components of the frequency-dependent magnetic susceptibility tensor and the dependence of the resonant frequency of the uniform pulsation modes of a stripe domain on the amplitude of the external magnetic field are determined.

Ferromagnetic resonance in nanostructures with temperature-controlled interlayer interaction

This study is a comprehensive analysis of a multilayer F1/f(d)/F2pin structures magnetic resonance properties, wherein F1 and F2pin are the free and exchange-coupled strong magnetic layers, and f is the weakly magnetic layer with a Curie point in the room temperature region. Depending on the magnetic state of the spacer f (ferromagnetic or paramagnetic) the exchange interaction between the F2 and F2pin layers becomes a function of the temperature, which opens up opportunities for practical applications. The obtained results show that the interlayer exchange coupling can be enhanced by decreasing the thickness of the spacer d, or by lowering the temperature. Strengthening the exchange coupling leads to a stronger manifestation of unidirectional anisotropy in the ferromagnetic resonance layer F1, as well as to a broadening of the resonance line that is atypical for thin films. The observed features are analyzed in the context of comparing the effects of two different natures: the influence of the spacer d ...

Spiral magnetic configuration in a thin film with biaxial anisotropy

The conditions for the existence of a spiral magnetic configuration are determined for a thin ferromagnetic film with biaxial anisotropy.

Effect of the inner structure of domain walls on the stability of an isolated stripe domain in a pulsed field

This paper studies the effect of the inner structure of domain walls on the stability of an isolated stripe domain localized in a thin ferromagnetic film against a pulse of magnetic field applied perpendicularly to the film surface. It is found that the value of the critical amplitude of the pulsed signal strongly depends on the value of the magnetizing field in which the system was initially placed. It is also established that the difference on stability of domains with unipolar and bipolar walls in pulsed fields diminishes as the amplitude of the magnetizing field decreases. Finally, the dependence of the region of stability in a pulse field on the parameters of the system is determined for various domain types.

Effect of the micromagnetic structure of domain walls on the properties of an isolated domain in a thin magnetic film

The effect of the inner structure of domain walls on the time-independent parameters of an isolated stripe domain in a thin ferromagnetic film is studied. The adopted variant of the perturbation theory makes it possible to account, within a unified approach, for the contributions of the magnetostatic and exchange interactions.