Efficient charge-spin conversion and magnetization switching through the Rashba effect at topological-insulator/Ag interfaces
Efficient charge-spin conversion and magnetization switching through the Rashba effect at topological-insulator/Ag interfaces
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DOI：
10.1103/physrevb.97.041115
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发表时间：
2018-01
影响因子：
3.7
通讯作者：
Shuyuan Shi;Aizhu Wang;Yi Wang;R. Ramaswamy;Lei Shen;J. Moon;D. Zhu;Jiawei Yu;Seongshik Oh;Y. Feng;Hyunsoo Yang
中科院分区：
文献类型：
--
作者：
Shuyuan Shi;Aizhu Wang;Yi Wang;R. Ramaswamy;Lei Shen;J. Moon;D. Zhu;Jiawei Yu;Seongshik Oh;Y. Feng;Hyunsoo Yang
我们报道了利用自旋矩铁磁共振技术在三维拓扑绝缘体（TI）Bi 2Se 3和Ag双层膜中观察到的有效的电荷-自旋转换。Bi 2Se 3/Ag/CoFeB异质结构中的自旋轨道扭矩比随着Ag厚度增加到约2nm而显示出显著增强，并且对于5 nm的Ag达到0.5的值，其在室温下比Bi 2Se 3/CoFeB的自旋轨道扭矩比高约3倍。结果表明，Bi 2Se 3/Ag的界面效应超过了Bi 2Se 3层的拓扑表面态（TSS），并在Bi 2Se 3/Ag/CoFeB系统的电荷-自旋转换中起主导作用.基于第一性原理计算，我们将我们的观察归因于大的Rashba分裂带，它包裹着TSS带，并且与Bi 2Se 3的TSS具有相同的净自旋极化方向。随后，我们第一次证明了在5.8 × 10^5 A/cm 2的低电流密度下Bi 2Se 3/Ag/Py中的Rashba诱导磁化翻转。
We report the observation of efficient charge-to-spin conversion in the three-dimensional topological insulator (TI) Bi2Se3 and Ag bilayer by the spin-torque ferromagnetic resonance technique. The spin orbit torque ratio in the Bi2Se3/Ag/CoFeB heterostructure shows a significant enhancement as the Ag thickness increases to ~2 nm and reaches a value of 0.5 for 5 nm Ag, which is ~3 times higher than that of Bi2Se3/CoFeB at room temperature. The observation reveals the interfacial effect of Bi2Se3/Ag exceeds that of the topological surface states (TSS) in the Bi2Se3 layer and plays a dominant role in the charge-to-spin conversion in the Bi2Se3/Ag/CoFeB system. Based on the first-principles calculations, we attribute our observation to the large Rashba-splitting bands which wrap the TSS band and has the same net spin polarization direction as TSS of Bi2Se3. Subsequently, we demonstrate for the first time the Rashba induced magnetization switching in Bi2Se3/Ag/Py with a low current density of 5.8 X 10^5 A/cm2.