Proceedings Article | 19 September 2017
KEYWORDS: Graphene, Dielectrics, Magnetism, Spintronics, Metals, Europium, Zeeman effect, Quantum information, Quantum physics, Quantum information processing
Topological insulators and graphene, the two representative 2D Dirac electron systems, have both been widely studied for spintronics applications. On the one hand, strong spin-orbit coupling in topological insulators makes them obvious spin source candidates. On the other hand, minute spin-orbit coupling in graphene makes it a promising spin transport channel. In this talk, I will first present our work on the charge-spin conversion in topological insulators. Our data demonstrate orders of magnitude improvement over conventional spin-Hall metals [1][2]. Furthermore, they indicate that the high spin generation efficiency originates from the spin-momentum locking of the topological surface states. In the second part of the talk, I will discuss the charge-spin conversion in graphene, when proximity coupled to a model magnetic insulator EuS. The interfacial exchange coupling produces a substantial Zeeman field (>= 14 T) in graphene, which yields orders-of-magnitude enhancement in spin generation by the Zeeman spin-Hall effect. Furthermore, the strong exchange field lifts the spin degeneracy in the graphene quantum Hall regime, which leads to novel spin-polarized edge transport features, potentially interesting for classical and quantum information processing [3].
[1] Luqiao Liu, A. Richardella, Ion Garate, Yu Zhu, N. Samarth, and Ching-Tzu Chen, Physical Review B 91, 235437 (2015).
[2] Luqiao Liu, Ching-Tzu Chen, and J. Z. Sun, Nature Physics 10, 561--566 (2014).
[3] Peng Wei, Sunwoo Lee, Florian Lemaitre, Lucas Pinel, Davide Cutaia , Wujoon Cha , Ferhat Katmis, Yu Zhu, Donald Heiman, James Hone, Jagadeesh S. Moodera, and Ching-Tzu Chen, Nature Materials 15, 711 (2016).
