Physics Department - Orbital Pairing Symmetry: From Sr2RuO4 to UTe2
Supporting the below United Nations Sustainable Development Goals:支持以下聯合國可持續發展目標：支持以下联合国可持续发展目标：
Abstract
A hallmark of unconventional superconductivity, which can be understood as a macroscopic quantum phenomenon associated with superconducting pairing in which symmetries beyond the U(1) symmetry are broken, is the non-s-wave orbital pairing symmetry, the mathematical characteristics of the orbital part of the superconducting order parameter (OP). Sr2RuO4 and UTe2 are two promising candidates for establishing experimentally the exotic orbital pairing symmetry of odd party, which implies for these two materials also the spin-triplet pairing due to the presence of an inversion symmetry. While Sr2RuO4 is the first and for a long time the only layered perovskite superconductor without the presence of Cu, whose superconductivity was found in the 90’s, UTe2 is a heavy fermion superconductor discovered more recently. The normal electronic states on the Fermi surface in Sr2RuO4 were shown to evolve primarily from 4d orbitals of Ru, forming a highly anisotropic, cylindrical Fermi surface. However, the electronic properties in UTe2 are dominated by strongly correlated 5f electrons of U. In this talk I will give a brief overview of the superconducting properties of Sr2RuO4 and UTe2 and discuss our own work on the phase-sensitive determination of the orbital pairing symmetries of these two superconductors. I will also comment briefly on the ongoing debate on the symmetry properties of the spin part of the OP in Sr2RuO4.
Ying Liu, a professor of physics at the Pennsylvania State University, received his BS degree from Peking University in 1982. He earned a MS degree from Institute of Physics, Chinese Academy of Sciences in 1984 and received his Ph.D. degree from the University of Minnesota, Twin Cities in 1991. After three-year postdoctoral research at University of Colorado, Boulder, Prof. Liu joined the faculty of Department of Physics of the Pennsylvania State University in 1994 and became a tenured full professor in 2005. His research is focused on the study of low-dimensional and unconventional superconductors, ferroelectricity, and related quantum phenomena. Professor Liu received an NSF Career Award in 1997 and was selected as a fellow of the American Physical Society in 2006.