Thermo-magneto-mechanical analysis of head–disk interface in heat assisted magnetic recording

Abstract

Heat Assisted Magnetic Recording (HAMR) is achieved by heating high-stability magnetic media while applying a magnetic field. Exposure to such a thermal load subjects the head–disk interface to intense thermal strain/stress fields, which can cause transient head–disk contact, failures such as plastic deformation, layer–substrate delamination and surface cracking of the head and disk. Furthermore, the stress field alters the preferred direction of magnetization and changes the shape of the magnetization curve below saturation, thereby affecting the magnetic performance such as the permeability in the head. Several 3D boundary/finite element based thermo-magneto-mechanical models are developed to investigate these reliability issues of the HAMR head–disk interface. The temperature elevations and the associated thermal strains and stresses, and their effects on HAMR mechanical and magnetic performances are predicted. Transfer functions are derived, which allow the specification of HAMR material's thermo-mechanical properties to alter the distributions of stresses and distortions, without changing the temperature elevation. An optimal head–disk interface design is predicted based on the simulation results.