Fizika Nizkikh Temperatur: Volume 43, Number 11 (November 2017), p. 1581-1593    ( to contents , go back )

Hysteresis of films with perpendicular anisotropy in an inclined magnetic field

S.M. Ryabchenko1 and V.M. Kalita1,2

1Institute of Physics of the National Academy of Sciences 46 Nauki Ave., Kiev 03028, Ukraine
E-mail: ryabch@iop.kiev.ua, ryabch@voliacable.com; vmkalita@ukr.net

2National Technical University of Ukraine “KPI”, 37 Peremogy Ave., Kiev 03056, Ukraine

Received May 29, 2017

Abstract

Numerical calculations are made of the magnetization reversal loops of nanogranular films with perpendicular anisotropy in an inclined magnetic field at a finite temperature for “quality parameters” of the film, both smaller and greater than unity. The calculation was carried out taking into account the demagnetizing field of the film in the two-level approximation for the energy of the granule. It is obtained that the hysteresis of the transition fields between states with the same direction of the magnetic moments of all the granules and with different directions, narrows with increasing temperature and of the angle of deviation of the field from the normal to the film. With increasing field deviation, this hysteresis vanishes, and the transition occurs from the uniformly magnetized state of the granules to an equilibrium nonuniform state, without hysteresis. In the case of large field deflection angles, at a finite temperature the magnetization consists of three sections. At the center of the magnetization curve, there is a hysteresis region with different direc-tions of the magnetic moments of the particles. As the absolute value of the field increases, it goes over to the region of equilibrium nonhysteretic magnetization with different directions of the magnetic moments of the particles. And after it this hysteresis-free region passes to a state with a homogeneous direction of the magnetic moments of all the particles.

PACS: 75.30.Gw Magnetic anisotropy;
PACS: 75.60.Jk Magnetization reversal mechanisms;
PACS: 75.60.Ej Magnetization curves, hysteresis; Barkhausen and related effects;
PACS: 75.70.Ak Magnetic properties of monolayers and thin films.

Key words: nanogranular film, perpendicular anisotropy, demagnetization field, hysteresis, coercive field.

Published online: September 25, 2017

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