Electrical Detection of Spin-Polarized Surface States Conduction in (Bi0.53Sb0.47)2Te3 Topological Insulator

详细信息    查看全文

• 作者：Jianshi Tang ; Li-Te Chang ; Xufeng Kou ; Koichi Murata ; Eun Sang Choi ; Murong Lang ; Yabin Fan ; Ying Jiang ; Mohammad Montazeri ; Wanjun Jiang ; Yong Wang ; Liang He ; Kang L. Wang
• 刊名：Nano Letters
• 出版年：2014
• 出版时间：September 10, 2014
• 年：2014
• 卷：14
• 期：9
• 页码：5423-5429
• 全文大小：527K
• ISSN：1530-6992

文摘

Strong spin鈥搊rbit interaction and time-reversal symmetry in topological insulators enable the spin-momentum locking for the helical surface states. To date, however, there has been little report of direct electrical spin injection/detection in topological insulator. In this Letter, we report the electrical detection of spin-polarized surface states conduction using a Co/Al₂O₃ ferromagnetic tunneling contact in which the compound topological insulator (Bi_0.53Sb_0.47)₂Te₃ was used to achieve low bulk carrier density. Resistance (voltage) hysteresis with the amplitude up to about 10 惟 was observed when sweeping the magnetic field to change the relative orientation between the Co electrode magnetization and the spin polarization of surface states. The two resistance states were reversible by changing the electric current direction, affirming the spin-momentum locking in the topological surface states. Angle-dependent measurement was also performed to further confirm that the abrupt change in the voltage (resistance) was associated with the magnetization switching of the Co electrode. The spin voltage amplitude was quantitatively analyzed to yield an effective spin polarization of 1.02% for the surface states conduction in (Bi_0.53Sb_0.47)₂Te₃. Our results show a direct evidence of spin polarization in the topological surface states conduction. It might open up great opportunities to explore energy-efficient spintronic devices based on topological insulators.

Keywords:

Topological insulator; spin polarization; surface states; spin-momentum locking; spin detection