A tunneling magnetoresistance sensor overlaid with a longitudinal bias stack

Abstract In this study, a tunneling magnetoresistance (TMR) sensor overlaid with a longitudinal bias (LB) stack is fabricated, its magnetic and TMR properties are characterized, and its read performance is tested. The TMR sensor comprises Ta/Ni–Fe/Pt–Mn/Co–Fe/Ru/Co–Fe/Al–O/Co–Fe/Ni–Fe/Cu films, and the LB stack comprises Ru/Co–Fe/Pt–Mn/Ta films. A transverse-field anneal is applied to the TMR sensor to develop strong antiferromagnetic/ferromagnetic coupling within the Pt–Mn/Co–Fe films in a transverse direction perpendicular to an air bearing surface (ABS), thereby forming a transverse flux closure within the Co–Fe/Ru/Co–Fe films for operating the TMR sensor properly. A longitudinal-field anneal is applied to the LB stack to develop strong ferromagnetic/antiferromagnetic coupling within the Co–Fe/Pt–Mn films in a longitudinal direction parallel to the ABS, thereby forming a longitudinal flux closure within the Co–Fe/Ni–Fe/Cu/Ru/Co–Fe films for attaining stable TMR responses. The TMR sensor exhibits good magnetic and TMR properties, including low ferromagnetic coupling fields, high pinning fields, low junction resistance-area products, and high TMR coefficients. The TMR sensor overlaid with the LB stack shows stable, highly sensitive TMR responses.