Description:

Professor Takeshi Mizushima, Osaka University, Japan

Title: Anomalous transport phenomena in nematic and Weyl superconductors

Abstract: Transport phenomena in topological superconductors (SCs) exhibit striking deviation from those of conventional SCs as their low-energy physics is governed by two characteristic ingredients: long-lived bosons and topological fermions. The former involves a coherent motion of a macroscopic fraction of particles, while the latter leads to a variety of topological phenomena including chiral anomaly and axion electrodynamics. In this seminar, I will discuss anomalous transport in nematic and Weyl SCs. Nematic superconductivity, which spontaneously breaks the crystalline symmetry of parent materials, has been observed in the family of doped topological insulators. I will show that along-lived Higgs boson, which involves the fluctuation of chirality (or orbital angular momentum of Cooper pairs) in the superconducting vacuum, softens when the 3D Fermi surface evolves into 2D cylindrical one. The softening is a signal of the nematic-to-Weyl superconducting phase transition, which is turned out to be detectable through the anomalous absorption of electromagnetic waves. I will further present new transport phenomena mediated by Weyl-Bogoliubov quasiparticles in Weyl SCs. This includes the “torsional” chiral magnetic effect due to the real-space skyrmion texture of Weyl points and negative magneto-thermal transport.

Host: Jim Sauls