Abstract

AP470

Thursday, 6 June 2019 at 3:15 pm

McCullough, First Floor Auditorium, Room #115

Host: Steve Kivelson

Stuart Brown

University of California, Los Angeles

¹⁷O NMR probe of the unconventional superconductivity in strained Sr₂RuO₄

The quasi-two-dimensional Sr₂RuO₄ has long been considered a solid state analog to the archetypal Fermi Liquid ³He, with strong normal state correlations, and odd-parity superconductivity in the ground state that also breaks time reversal symmetry. A split superconducting transition is expected under conditions of in-plane strain along [100], since the distortion removes the degeneracy of the proposed two-component order parameter. Instead, a strong peak in T_c was observed. This and other puzzles motivated our study of the normal and superconducting states using ¹⁷O NMR under stressed conditions. The normal state Knight shifts are consistent with tuning E_F through a van Hove singularity, along with an associated Stoner factor enhancement. A reduced spin polarization is observed in the superconducting state for all strains, eliminating the chiral p-wave state as a possible superconducting order parameter.