ABSTRACT
Symmetry plays a fundamental role in our understanding of both conventional symmetry breaking phases and the more exotic quantum and topological phases of matter. We explore the experimental signatures of symmetry enriched U(1) quantum spin liquids (QSLs) on the pyrochlore lattice. We point out that the Ce local moment of the newly discovered pyrochlore QSL candidate Ce2Sn2O7, is a dipole-octupole doublet. The generic model for these unusual doublets supports two distinct symmetry enriched U(1) QSL ground states in the corresponding quantum spin ice regimes. These two U(1) QSLs are dubbed dipolar U(1) QSL and octupolar U(1) QSL. While the dipolar U(1) QSL has been discussed in many contexts, the octupolar U(1) QSL is rather unique. Based on the symmetry properties of the dipole-octupole doublets, we predict the peculiar physical properties of the octupolar U(1) QSL, elucidating the unique spectroscopic properties in the external magnetic fields. We further predict the Anderson-Higgs transition from the octupolar U(1) QSL driven by the external magnetic fields. We identify the experimental relevance with the candidate material Ce2Sn2O7 and other dipole-octupole doublet systems.
Refs: Yao-Dong Li and Gang Chen, Phys. Rev. B 95, 041106(R) (2017).
BIOGRAPHY
Prof Gang Chen received his bachelor's degree from USTC in 2004 and graduated with the University's highest honor. He received his PhD in 2010 from Univ of California, Santa Barbara, working with Prof Leon Balents from the Kavli Institute for Theoretical Physics. He was appointed the professor position in 2015 at Fudan University, and elected into the 1000-youth-talent program. In 2017, he was awarded the Daniel Tsui Fellowship from The University of Hong Kong. Prof Chen has a broad interest in condensed matter theory, and most of his works are experimentally motivated.