Quantum materials have recently exhibited many unique spin-dependent properties, which could be promising material candidates for spintronics [1]. On the other hand, pure spin current, flow of spin angular momentum without the company of any charge current, can be a useful probe for interesting quantum materials/states.

In this talk, I will present our recent experimental results on using pure spin current as a probe for topological insulators, spin superfluid ground states, and the interface at ferromagnetic-superconductor heterostructures. I will first talk about the pure spin current in SmB6 and resonant magnon absorption in (BixSb1-x)2Te3, which are consistent with the spin-momentum locked properties of the topological surface states [2,3]. Then I will discuss the pure spin current transport in canted antiferromagnet Cr2O3, suggesting the existence of spin superfluid ground state at low temperatures [4]. The last part of my talk will talk about the spin dynamics in an s-wave superconductor in the heterostructures of ferromagnet/superconductor [5], from which the superconducting gap properties at the interface could be inferred. 
 
References:
[1] W. Han*, Y. Otani, and S. Maekawa, npj Quantum Materials, 3, 27 (2018).
[2] Q. Song, J. Mi, D. Zhao, T. Su, W. Yuan, W. Xing, Y. Chen, T. Wang, T. Wu, X. H. Chen, X. C. Xie, C. Zhang*, J. Shi*, and W. Han*, Nat. Commun. 7:13485 (2016).
[3] C. Tang#, Q. Song#, C. Chang, Y. Ohnuma, M. Matsuo, Y. Liu, W. Yuan, Y. Yao, J. S. Moodera, S. Maekawa, W. Han, and J. Shi*, Science Advances, 4, eaas8660 (2017).
[4] W. Yuan, Q. Zhu, T. Su, Y. Yao, W. Xing, Y. Chen, Y. Ma, X. Lin, J. Shi*, R. Shindou, X. C. Xie*, and W. Han*, Science Advances, 4, eeat1098 (2018).
[5] Y. Yao, Q. Song, Y. Takamura, J. Cascales, W. Yuan, Y. Ma, Y. Yun, X. C. Xie, J. S. Moodera, and W. Han*, Phys. Rev. B, in press (2018), arXiv:1710.10833.

韩伟简介
北京大学量子材料科学中心研究员，博士研究生导师。2006年获得中国科学技术大学获得材料物理本科学。2012年1月获得University of California, Riverside物理学博士学位。2012年1月至2014 年09月在IBM Almaden Research Center进行博士后研究工作。2014 年09月入职北京大学量子材料科学中心，并在2015年初获得中组部青年千人计划资助。主要研究方向是自旋电子学和量子材料。荣获2012年美国物理学会优秀博士论文奖和2016年国际纯粹与应用物理学联合会（IUPAP） 青年科学家奖。