Efficient charge-spin conversion and magnetization switching through the Rashba effect at topological-insulator/Ag interfaces

作     者：Shuyuan Shi Aizhu Wang Yi Wang Rajagopalan Ramaswamy Lei Shen Jisoo Moon Dapeng Zhu Jiawei Yu Seongshik Oh Yuanping Feng Hyunsoo Yang 

作者机构：Department of Electrical and Computer Engineering National University of Singapore Singapore 117576 Singapore Department of Physics National University of Singapore Singapore 117542 Singapore Department of Mechanical Engineering & Engineering Science Programme National University of Singapore Singapore 117575 Singapore Department of Physics and Astronomy Rutgers The State University of New Jersey Piscataway New Jersey 08854 USA 

出 版 物：《Physical Review B》 (Phys. Rev. B)

年 卷 期：2018年第97卷第4期

页      面：041115(R)-041115(R)页

核心收录：

基　　金：Agency for Science  Technology and Research  A*STAR 

主　　题：First-principles calculations Magnetotransport Spin current Spin-orbit coupling Spintronics Surface states Topological materials Topological phases of matter 

摘      要：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 (TSSs) in the Bi2Se3 layer and plays a dominant role in the charge-to-spin conversion in the Bi2Se3/Ag/CoFeB system. Based on first-principles calculations, we attribute our observation to the large Rashba splitting bands which wrap the TSS band and have the same net spin polarization direction as the TSS of Bi2Se3. Subsequently, we demonstrate Rashba-induced magnetization switching in Bi2Se3/Ag/Py with a low current density of 5.8×105A/cm2.