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New ways to detect the pairing symmetry in superconductors

The pairing symmetry, mathematically defined as the representation of the unbroken symmetry group carried by the pairing order parameter, is considered as a classification and characterization of the broken symmetries in a superconductor. In this talk, we will introduce another concept, known as the projective symmetry group (PSG) of a superconductor. We will show that the PSG imposes a strong constraint on the pairing symmetry, and in many cases has a one-to-one correspondence with the pairing symmetry. This map from PSG to pairing symmetry allows us to identify two new ways to detect pairing symmetry in a superconductor: (1) through new selection rules in optical/THz and Raman spectroscopy, (2) through the presence/absence of Majorana zero modes in vortex cores centered at high-symmetry locations of the crystal. I will illustrate the results using examples of superconductors w/ or w/o spin-orbit interactions. 

Host: Hae-Young Kee
Event series  Toronto Quantum Matter Seminars