Adaptive Bias Control for Magnetic Recording Head

Abstract

A method of forming a read head is described where a Tunneling Magnetoresistive (TMR) stack of layers comprised of a free layer (FL) and having sidewalls separated by a cross-track width is formed on a bottom shield. In subsequent steps, a first insulation layer and longitudinal biasing layer are formed on the sidewalls and bottom shield. After a TMR sensor backside is formed that exposes the bottom shield, a second insulation layer and permanent magnet (PM) layer are deposited on exposed portions of the bottom shield. Thereafter, the PM layer magnetization is initialized in a direction that adjusts FL bias point, and shifts sensor asymmetry (Asym) closer to 0% for individual heads at slider or Head Gimbal Assembly level to provide a significant improvement in device yield. Asym is adjusted using different initialization schemes and initialization directions. With individual heads, initialization direction is selected based on a prior asymmetry measurement.

Dependencies are inferred from the claim text.