[25a-E201-1~11] 10.3 スピンデバイス・磁気メモリ・ストレージ技術

▲ [25a-E201-2] Giant tunnel magnetoresistance in Fe/Mg₄Al-O_x/Fe(001) magnetic tunnel junctions

Thomas Scheike¹、Zhenchao Wen¹、〇Hiroaki Sukegawa¹、Seiji Mitani¹ (1.NIMS)

キーワード：tunnel magnetoresistance, magnetic tunnel junction

Recently, we demonstrated significantly large TMR ratios using a conventional Fe/MgO/Fe(001) MTJ structure; 417% at room temperature (RT) (914% at 5 K) is almost twice (three times) as large as the typical ratios in Fe/MgO/Fe reports. However, due to the large lattice mismatch between Fe and MgO, many misfit dislocations are introduced at their interfaces, which limits further improvement of the TMR ratio. In this study, we report enhanced TMR ratios using a Mg-rich spinel barrier, Mg₄Al-O_x. We observed the maximum TMR ratio is 429% at RT. At 10 K, the TMR ratio exceeds thousand percent (up to 1,034%), reaching typical theoretical values of Fe/MgO/Fe(001). The TMR ratio shows significant oscillatory behavior with a ~0.31 nm period and a large peak-to-valley difference of 125% at RT. These features may be attributed to improved barrier interfaces by lattice-tuning effect of a spinel MgAl₂O₄-based barrier.