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The 332nd forum: Proximitized Materials

Date: 2018-05-23
Time: 15:00
Venue: 中科院物理研究所M楼236报告厅
Speaker: Professor Igor Zutic

University at Buffalo, the State University of New York

Igor ?uti? received his Ph.D. in theoretical physics at the University of Minnesota in 1998, after undergraduate studies at the University of Zagreb, Croatia. He was a postdoc at the University of Maryland and the Naval Research Lab. In 2005 he joined the State University of New York at Buffalo where he is a Full Professor. His review Spintronics: Fundamentals and Applications, for Reviews of Modern Physics is currently among the most cited articles on spin transport and magnetism. ?uti?’s work spans topics from high-temperature superconductors, Majorana fermions, unconventional magnetism, to prediction of various spin-based devices that are not limited to the concept of magnetoresistance. He has published over 100 refereed articles and given over 140 invited presentations on spintronics, magnetism, and superconductivity. Igor ?uti? is a recipient of 2006 National Science Foundation CAREER Award, and a Fellow of American Physical Society.

Proximity effects can transform a given material through its adjacent regions to become superconducting, magnetic, or topologically nontrivial[1]. In bulk materials, the sample size often greatly exceeds the characteristic lengths of proximity effects allowing their neglect. However, in 2D materials such as graphene, transition-metal dichalcogenides (TMDs) and 2D electron gas (2DEG), the situation is drastically different. Even short-range magnetic proximity effects exceed their thickness and strongly modify spin transport and optical properties[2,3]. Experimental confirmation[4] of our prediction for bias-controlled spin polarization reversal in Co/h- BN/graphene[2] suggests that magnetic proximity effects may overcome the need for an applied magnetic field and a magnetization reversal to implement spin logic[5]. In TMDs, where robust excitons dominate their optical response, magnetic proximity effects cannot be described by the single-particle description. We predict a conversion between optically inactive and active excitons by rotating the magnetization of the substrate[3]. Combined magnetic and superconducting proximity effects could enable elusive Majorana bounds states (MBS) for fault-tolerant quantum computing. Exchanging (braiding) MBS yields a noncommutative phase, a sign of non-Abelian statistics and nonlocal degrees of freedom protected from local perturbations. MBS could be manipulated and braided in proximity-induced superconductivity in a 2DEG with magnetic textures from the fringing fields of magnetic tunnel junctions[6].
[1] I. ?uti? et al., Materials Today, in press.
[2] P. Lazi?, K. Belashchenko, I. ?uti?, PRB 93, 241401(R) (2016).
[3] B. Scharf et al., PRL 119, 127403 (2017).
[4] J. Xu et al., arXiv:1802.07790, Nat. Commun., in press.
[5] H. Wen et al., Phys. Rev. Appl. 5, 044003 (2016).
[6] G. Fatin et al., PRL 117, 077002 (2016).

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