Time: 10:00am (UTC/GMT+8:00, Beijing/Shanghai), May 21 (Fri.), 2021

Venue: Rm. 830, M Building, Institute of Physics (IOP, CAS)

Speaker: Zheng-Xin Liu (Renmin Univ.)

Abstract:

Quantum spin liquid (QSL) candidates on triangular lattice can promisingly realize U(1) gapless QSL with spinon fermi surface. In this talk, we study the effect of Dzyaloshinskii-Moriya (DM) interaction on the triangular lattice U(1) gapless QSL which is stabilized by ring-exchange interactions. A weak DM interaction introduces a staggered flux to the U(1) QSL state and changes the density of states at the spinon fermi surface. If the DM vector contains in-plane components, then the spinons gain nonzero Berry phase. The resultant thermal conductances κxx and κxy qualitatively agree with the experimental results on the material EtMe3Sb[Pd(dmit)2]2. Furthermore, owing to perfect nesting of the fermi surface, a spin density wave state is triggered by larger DM interactions. On the other hand, when the ring- exchange interaction decreases, another anti-ferromagnetic (AFM) phase with 120◦ order shows up which is proximate to a U(1) Dirac QSL. We discuss the difference of the two AFM phases from their static structure factors and excitation spectra.

About the speaker:

Dr. Zheng-Xin Liu obtained his Ph.D in the Hong Kong University of Science and Technology in 2010. After that he worked in the Institute for Advanced Study in Tsinghua University as a post doctor and then as an associate member. He joined Renmin University of China in 2015 as an associate professor. Dr. Liu's research area includes quantum magnetism, symmetry protected topological phases, and numerical methods in many-body physics. Recently, his interest is focused on magnetic systems, including quantum spin liquids and magnetic semimetals.

Invited by Prof. Zheng Zhu