R&D: Influence of Anisotropy Constant on Writability in Heated-Dot Magnetic Recording

Journal of the Magnetics Society of Japan has published an article written by T. Kobayashi, Graduate School of Engineering, Mie Univ., Y. Nakatani, Graduate School of Informatics and Engineering, Univ. of Electro-Communications, and I. Tagawa, Electrical and Electronic Engineering, Tohoku Institute of Technology.

Abstract: “We discuss the influence of the anisotropy constant on writability, taking account of 10 years of archiving and adjacent track interference in 4 Tbpsi shingled heated-dot magnetic recording (HDMR), using our stochastic calculation employing the Néel-Arrhenius model with a Stoner-Wohlfarth dot. The bit error rate is calculated and the result is analyzed using the mean magnetization reversal number per unit time as a function of the writing time. We confirm the stochastic calculation result by employing a micromagnetic simulation. HDMR has a certain margin for erasure-after-write, since half of the writing time determined by field is for the magnetic dot and the rest is for the nonmagnetic spacing. HDMR also has a certain margin for the dot aspect ratio, since the dot is relatively large. Therefore, the combination of a small anisotropy constant and a large dot volume can be used to improve write-error. When we choose a small anisotropy constant, the mean magnetization reversal number per unit time in the opposite direction to the recording direction is negligible. Furthermore, the writing time determined by medium is longer. Therefore, the bit error rate caused by write-error is low for a small anisotropy constant.“