Monte Carlo simulation of thermal fluctuation in magnetization of longitudinal and perpendicular magnetic recording media

Thermal stability in longitudinal thin film media

“…Table I shows the media parameters. The distribution of the grain sizes was assumed to follow a -Gaussian distribution [4] (2)…”

“…It has not been fully clarified, however, whether media that have identical values of will have the same signal decay ratios. In this work, a Monte-Carlo simulation [4], [5] was performed to clarify these points. First, the mechanism that connects the signal decay ratio with the recording density is studied, with consideration of the magnetic fields applied on grains.…”

Dependence of prefactor on the angle between an applied field and the easy axis for single-domain particles

“…For the thermally reinforced reversal of magnetization crossing an energy barrier, the reversal rate is proportional to the prefactor with the Arrhenius formula. Furthermore, the prefactor is a key factor for the micromagnetic simulation with the Monte Carlo method [1]. The relaxation time of the magnetization of uniaxial singledomain ferromagnetic particles has been studied by Kalmykov for barrier height parameter sð ¼ K u v=k B T, here K u : the anisotropy energy, v: the volume of the particle, k B : the Boltzmann constant, T: the temperature) of less than 15 and the applied field of less than 0.3 with respect to the anisotropy field [2].…”

Time dependence of readout signal and media noise

“…T HE INFLUENCE of thermal fluctuation on magnetic recording media is considered to be an important factor which limits recording density and has been investigated by experiments and computer simulations [1], [2], [4]. Although the decay with time in the readout signal was mainly reported in these investigations, the change in the media noise with time has not yet been reported.…”