強磁性体/Al-Oxide/Co接合のトンネル磁気抵抗効果の印加電圧及び温度依存性

抄録

Ferromagnetic tunneling junctions with various thicknesses of the first ferromagnetic layer were fabricated. Co and Ni₈₀Fe₂₀ were used as the first ferromagnetic layer, and their thicknesses were varied between 10 and 200 Å. The voltage and temperature dependence of the tunneling magnetoresistance (TMR) ratio and conductance characteristic were investigated for these junctions. A drastic decrease in the conductance near the zero bias in the conductance-voltage characteristics (zero-bias anomaly) was observed in some junctions. A rapid decrease in the TMR ratio below 5 mV and 50 K was also observed in the same junctions. A slight decrease in the TMR ratio above 10 mV and 100 K was observed in all junctions. We investigated the origin of the voltage and temperature dependence of the TMR ratio by taking account of the magnetic impurity and magnon effect.