Simulations of magnetic hysteresis loops at high temperatures

Abstract

Articles you may be interested inEffects of grain microstructure on magnetic properties in FePtAg-C media for heat assisted magnetic recording Magnetic and structural properties of hexagonal-close-packed-CoCrPt-C granular media for high areal density recordingThe kinetic Monte-Carlo algorithm as well as standard micromagnetics are used to simulate MH loops of high anisotropy magnetic recording media at both short and long time scales over a wide range of temperatures relevant to heat-assisted magnetic recording. Microscopic parameters, common to both methods, were determined by fitting to experimental data on single-layer FePt-based media that uses the Magneto-Optic Kerr effect with a slow sweep rate of 700 Oe/s. Saturation moment, uniaxial anisotropy, and exchange constants are given an intrinsic temperature dependence based on published atomistic simulations of FePt grains with an effective Curie temperature of 680 K. Our results show good agreement between micromagnetics and kinetic Monte Carlo results over a wide range of sweep rates. Loops at the slow experimental sweep rates are found to become more square-shaped, with an increasing slope, as temperature increases from 300 K. These effects also occur at higher sweep rates, typical of recording speeds, but are much less pronounced. These results demonstrate the need for accurate determination of intrinsic thermal properties of future recording media as input to micromagnetic models as well as the sensitivity of the switching behavior of thin magnetic films to applied field sweep rates at higher temperatures. V C 2014 AIP Publishing LLC. [http://dx.

Model of advanced recording media: The angular dependence of the coercivity including the effect of exchange interaction

“…There have been several works proposing experimental 6,7 and theoretical [8][9][10] methods to investigate the easy axis distribution. Experimentally, the measurement of crystalline dispersion or c-axis dispersion characterized by the full-width half maximum (FWHM) of the X-ray rocking curve 6,7 is often-used.…”

“…In this paper, we develop an advanced micromagnetic model based on the kinetic Monte Carlo (kMC) approach to simulate media including a realistic approach to the introduction of interactions. This approach allows to investigate the effect of intergranular exchange interaction and dipolar interaction and to study the magnetic behavior for the long time scale associated with thermally assisted grain reversal based on the Arrhenius-Néel Law 8,10,21 . We perform simulations of PRM using the kMC model to investigate theoretically the angular dependence of the coercivity including the influence of exchange interaction.…”