Bias Voltage Dependence of Tunneling Magnetoresistance and Annealing Effect in Spin Dependent Tunnel Junctions

概要

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Junctions with Al_2O_3 and AIN barriers were fabricated through contact shadow masks (0.25mm^2-size) and by a self-aligned lithography process (9×2μm^2-size).the Al_2O_3 barrier was formed by plasma oxidation. The AIN barrier was prepared by dc reactive magnetron sputtering. Room temperature tunneling magnetoresistance (TMR) is 1.6% for the AIN junctions and up to 24% for the Al_2O_3 junctions. The TMR for all junctions decreases with increase of applied bias voltage and drops to half its initial value at a bias voltage between 116 mV and 437 mV. The weakest bias voltage dependence occurs for junctions with higher barrier heights, and thinner barrier thickness. Annealing at 100〜200℃ leads to a 20% increase of TMR and a 40% decrease of junction resistance for the 9×2μm^2 junctions, leading to a maximum TMR of 27%. Both TMR and junction resistance were increased for the AIN junctions due to annealing.
社団法人日本磁気学会の論文
1999-01-20