The Left Hand of the Electron -- Anomalous Hall Transport in Chiral Superconductors

Condensed Matter Physics Seminar, University of California San Diego

Speaker: J. A. Sauls
Center for Applied Physics & Superconducting Technologies, Northwestern University and Fermi National Accelerator Laboratory
Department of Physics & Astronomy, Northwestern University, Evanston, Illinois
June 2, 2021

Abstract: Just over sixty years ago parity violation by the weak force was demonstrated in experiments led by C. S. Wu on the asymmetry of electron currents emitted in the beta decay of polarized 60Co. The asymmetry reflects two broken symmetries - mirror refelctions and time-reversal, the latter imposed by an external magnetic field. That same year Bardeen, Cooper and Schrieffer published the celebrated BCS theory of superconductivity, and soon thereafter Anderson and Morel proposed that the ground-state of liquid 3He was likely a BCS condensate of chiral p-wave Cooper pairs, exhibiting spontaneously broken mirror reflection and time-reversal symmetries. Indeed the high-pressure phase, superfluid 3He-A, discovered in 1972, is the realization of the Anderson-Morel state. However, definitive proof that 3He-A spontaneously breaks mirror and time-reversal symmetry came 41 years later with the observation an anomalous Hall effect for electrons moving in superfluid 3He-A.1 I discuss this discovery and the theory of the anomalous Hall effect for electrons moving in the chiral phase of 3He.2 I explain the origin of the transverse force on an electron moving in the chiral vacuum, and discuss implications of this theory, and its extension, to anomalous Hall transport for the broad class of chiral superconductors, including candidates for chiral superconductivity: Sr2RuO4, UPt3, URu2Si2 UTe2 etc.3

  1. H. Ikegami, Y. Tsutsumi, & K. Kono, Chiral Symmetry in Superfluid 3He-A, Science, 341,59-62, 2013.
  2. O. Shevtsov & J. A. Sauls, Electrons & Weyl Fermions in Superfluid 3He-A, Phys. Rev. B, 94, 064511, 2016.
  3. V. Ngampruetikorn & J. A. Sauls, Anomalous Thermal Hall Effect in Chiral Superconductors, PRL 124, 157002 (2020)

This research was supported by NSF Grant: DMR-1508730

Slides: [PDF]

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