Thermal effects induced lateral head shift of thermal flying height control perpendicular magnetic recording head

Abstract

In this paper, we report a lateral shift of the read/write head due to thermal actuated protrusion by heating currents as well as writing currents as experimentally observed by atomic force microscopy. It was found that the shift amplitude is approximately proportional to the heating power within working range before saturation, which is consistent with the relationship between reduction of flying height and heating power. Scanning thermal microscopy (SThM) was further used to measure the magnitude of temperature change before and after thermal activation as well as the localized temperature distribution around the active region. The measured temperature change as large as ∼66 K by SThM gave a reasonable explanation for the observed significant lateral shift for non-flying conditions (as large as ∼758 nm along the down-track direction and ∼347 nm along the cross-track direction for heater power ∼16 mW). The asymmetry in fabricated head structures/heating profiles of the working head is proposed to be the cause of the observed lateral shift. The thermal activation induced off-track and down-track effect and the asymmetry may need to be considered in the design of thermal actuated flying height control and in accurate positioning control as areal density of disks increases.