All-metal current-perpendicular-to-plane giant magnetoresistance sensors for narrow-track magnetic recording

Read heads using current-perpendicular-to-plane (CPP) giant magnetoresistance sensors have been fabricated and tested under highdensity recording conditions. A magnetoresistance of 5.5% and shield-to-shield spacing of 45 nm have been achieved by using an all-metal single-spin-valve with Heusler-alloy-based free and reference magnetic layers. Read heads with magnetic read widths ~45 nm were tested on perpendicular media, resulting in signals above 1 mV and signal-to-noise ratio ~30 dB. Linear densities in excess of 1050 kbpi were achieved with thermal fly-height control, compatible with recording areal densities of ~ 400 Gb/in (2). Current-induced spin-torque effects in the recording head were observed to result in rapid performance degradation above a threshold bias voltage of about 75 mV, corresponding to current densities > 10 (8) A/cm (2). Index Terms--CPP-GMR, magnetic recording, read-head, spin-valve.