Enhanced Signal-to-Noise Ratio in Current-Perpendicular-to-Plane Giant-Magnetoresistance Sensors by Suppression of Spin-Torque Effects

We report a ~4 dB enhancement in signal-to-noise ratio of current-perpendicular-to-the-plane giant magnetoresistance sensors with Heusler alloy magnetic layers due to insertion of an In-Zn-O electrically conductive oxide into an Ag-based metallic spacer layer. Signal and noise device characterization at various magnetic bias conditions shows that this enhancement arises from an increase in magnetoresistance signal at higher bias currents without spin-torque-induced magnetic instability. The best obtained signal-to-noise, over 30 dB for 1 GHz bandwidth, promises application of these sensors in magnetic recording heads for hard-disk drives at recording densities above 1 Tbit/in
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