2019年第80回応用物理学会秋季学術講演会

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コードシェアセッション » 【CS.8】 10.1 新物質・新機能創成(作製・評価技術)、10.2 スピン基盤技術・萌芽的デバイス技術、10.3 スピンデバイス・磁気メモリ・ストレージ技術、10.4 半導体スピントロニクス・超伝導・強相関のコードシェアセッション

[20a-E216-7~13] 【CS.8】 10.1 新物質・新機能創成(作製・評価技術)、10.2 スピン基盤技術・萌芽的デバイス技術、10.3 スピンデバイス・磁気メモリ・ストレージ技術、10.4 半導体スピントロニクス・超伝導・強相関のコードシェアセッション

2019年9月20日(金) 10:45 〜 12:30 E216 (E216)

谷口 知大(産総研)

11:00 〜 11:15

[20a-E216-8] Spin-orbit torque magnetization switching in a perpendicularly magnetized ferromagnetic-semiconductor single layer: Damping like torque and field like torque

〇(D)Miao JIANG1、Hirokatsu Asahara1、Shoichi Sato1、Shinobu Ohya1,2,3、Masaaki Tanaka1,2 (1.Dept. of Electrical Engineering, The Univ. of Tokyo、2.CSRN, Graduate School of Engineering, The Univ. of Tokyo、3.Institute of Engineering Innovation, Graduate School of Engineering, The Univ. of Tokyo)

キーワード:spin-orbit torque switching, damping like torque, field like torque

Spin-orbit torque (SOT) magnetization switching, which is induced by a spin current generated by a charge current, is a promising phenomenon that can be used to improve the performance of magnetoresistive random access memory. In our previous study, we achieved a highly efficient full SOT magnetization reversal in a GaMnAs single layer by applying a very low current density (Jc) of 3.4×105 A cm-2, which is two orders of magnitude smaller than that required in the conventional SOT systems. According to the Landau–Lifshitz–Gilbert (LLG) equation, the SOT is contributed by two parts; damping like torque (DLT) and field like torque (FLT). By fitting simulated results using the LLG equation to the experimental results, we clarified that the DLT is dominant during the magnetization switching in the 7-nm-thick GaMnAs single layer.
Here, we explore the contributions of DLT and FLT by inducing the SOT switching in perpendicularly magnetized GaMnAs single layers with different thicknesses; d = 5 nm, 7 nm, 10 nm, and 15 nm. In the GaMnAs single layer with d = 5nm, SOT magnetization switching (dominated by DLT) is observed with Jc = 1.6×105 A cm-2, which is even smaller than that of our previous paper. With the increase of d, the FLT starts to act on the magnetization switching and competes with the DLT. When d < 15 nm, Jc increases as d increases, which is caused by the enhancement of the contribution of FLT. At d = 15 nm, the switching polarity is totally reversed, indicating that the FLT becomes dominant. This result is understandable, considering that the acting direction of FLT is opposite to that of DLT. Our finding will advance the understanding on the contributions of DLT and FLT during the SOT switching in GaMnAs single layer, which will promote the development of SOT devices in the practical application.