A quantum model for the magnetic multi-valued recording

Abstract

We have proposed a quantum model for the magnetic multi-valued recording in this paper. The hysteresis loops of the two-dimensional systems with randomly distributed magnetic atoms have been studied by the quantum theory developed previously. The method has been proved to be exact in this case. We find that the single-ion anisotropies and the densities of the magnetic atoms are mainly responsible for the hysterisis loops. Only if the magnetic atoms contained by the systems are of different (not uniform) anistropies and their density is low, there may be more sharp steps in the hysteresis loops. Such materials can be used as the recording media for the so-called magnetic multi-valued recording. Our result explained the experimental results qualitativly.Comment: 10 pages containing one Table. Latex formatted. 5 figures: those who are interested please contact the authors requiring the figures. Submitted to J. Magn. Magn. Mater. . Email address: zlin@fudan.ihep.ac.c

Quantum approach for magnetic multilayers at finite temperatures

“…[8][9][10][11][12][13][14][15][16] Recently, a quantum theory based on this model was established to calculate the hysteresis loop and the coercivity of a magnetic multilayer, 14 and was applied to give a basic consideration of the magnetic multivalued ͑MMV͒ recording in double-film structures 15 and in magnetic granular film. 16 Some authors have tried to extend their methods to finite temperature, for example, using the molecular-field approximation which is good for the hightemperature case, 9 naively applying the Bose-Einstein statistics which is better for the very-low-temperature case 11 or some other assumptions. 12 On the other hand, some authors were devoted to making the model more realistic by including the long-ranged dipolar interactions in their Hamiltonian.…”