Seminar: Two-dimensional topological superconducting phases emerged from d-wave superconductors in proximity to antiferromagnets

Time:
4:00pm, Thursday, May 18^th, 2017

Location:
Room 242, East 4 teaching building, Zijingang Campus

Guang-Ming Zhang

Department of Physics, Tsinghua University, Beijing, China

Abstract

Motivated by the recent observations of nodeless superconductivity in the monolayer CuO₂ grown on the Bi₂Sr₂CaCu₂O_8+d substrates, we study the two-dimensional superconducting (SC phases described by the two-dimensional t-J model in proximity to an antiferromagnetic (AF) insulator. We found that (i) he nodal d-wave SC state can be driven via a continuous transition into a nodeless d-wave pairing state by the proximity induced AF field. (ii) The energetically favorable pairing states in the strong field regime have extended s-wave symmetry and can be nodal or nodeless. (iii) Between the pure d-wave and s-wave paired phases, there emerge two topologically distinct SC phases with (s+id) symmetry, i.e., the weak and strong pairing phases, and the weak pairing phase is found to be a Z₂ topological superconductor protected by valley symmetry, exhibiting robust gapless non-chiral edge modes. These finding strongly suggest that the high-T_c superconductors in proximity to antiferromagnets can realize fully gapped symmetry protected topological SC.

 

Biography of Prof. Guang-Ming Zhang

Guang-Ming Zhang was born n Beijing on he 18th of October, 1963. He graduated from Shanghai Jiaotong University and got his Ph. D. degree in Physics in 1991. From 1992 to 1994, h worked at ICTP, Trieste, Italy as a research fellow, and then he moved to Imperial College of London, UK as a research associate until 1997. At the end of 1997, he took a research scientist position at Center for Advanced Study in Tsinghua University. Starting from 2004, he worked at Department of Physics in Tsinghua as a full professor.

The main research interests of Guang-Ming Zhang are on the strongly correlated electron systems. He had made great contributions to the Kondo resonance phenomena in interacting electronic systems and characterizations of topological phases of matter and their phase transitions in low-dimensional correlated systems. In 1999, he was awarded “Outstanding Young Scholar” from Qiu Shi Science and Technologies Foundation. He got the award of “Outstanding Young Scholar Grant” from Natural Science Foundation of China in 2001. In 2005, he was appointed as Changjiang Professorship by Ministry of Education in China. He was awarded “Yeh Chi-Sun Prize for Condensed Matter Physics” by the Chinese Physical Society in 2011.