2017年第78回応用物理学会秋季学術講演会

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10 スピントロニクス・マグネティクス » 10.3 スピンデバイス・磁気メモリ・ストレージ技術

[8a-A413-1~7] 10.3 スピンデバイス・磁気メモリ・ストレージ技術

10.1と10.2と10.3のコードシェアセッションあり

2017年9月8日(金) 09:00 〜 10:45 A413 (413)

小山 知弘(東大)

09:15 〜 09:30

[8a-A413-2] Theory for bias voltage effects on spin-dependent transport properties in Fe/MgAl2O4/Fe(001) junctions

Keisuke Masuda1、Yoshio Miura1,2 (1.NIMS、2.KIT)

キーワード:magnetic tunneling junctions, bias voltage effects

In this work, we theoretically study bias voltage effects on tunneling magnetoresistive properties in Fe/MgAl2O4/Fe(001) magnetic tunneling junctions (MTJs) by comparing them with those in typical Fe/MgO/Fe(001) MTJs. We calculated bias voltage dependences of magnetoresistance (MR) ratios in both the MTJs by using the density-functional theory and the nonequilibrium Green’ function method. We see that in both the MTJs, the MR ratio decreases as the bias voltage V increases and eventually vanishes at a critical value Vc. We also see that the MgAl2O4-based MTJ has a larger Vc than the MgO-based one. Since the in-plane lattice constant of Fe/MgAl2O4/Fe(001) is twice as that of Fe/MgO/Fe(001), the Fe electrodes in the MgAl2O4-based MTJ have an identical band structure to that obtained by folding the Fe band structure of the MgO-based MTJs. From detailed analyses of band-resolved transmittances, we clarified that the difference in Vc between the MgAl2O4- and MgO-based MTJs is attributed to such a band-folding effect.