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Condensed Matter Seminar – Takeshi Mizushima (Osaka University)
Chiral Anomaly Phenomena in Weyl Superconductors
The Bogoliubov quasiparticles of Weyl superconductors/superfluids are a condensed matter realization of Weyls fermions. Weyl fermions are characterized by nonzero Berry curvature in momentum space which stems from monopole charges at Weyl points. In Weyl “semimetals”, this feature results in various intriguing electromagnetic response associated with chiral anomaly. This includes the chiral magnetic effect, anomalous quantum Hall effect, and negative magnetoresistivity. In Weyl “superconductors”, including the superfluid 3He-A and U-based superconductors, however, the chiral anomaly phenomena cannot be realized by simply applying electromagnetic fields as Weyl-Bogoliubov quasiparticle cannot carry definite charges. In this talk, I will propose two chiral anomaly phenomena in Weyl superfluids/superconductors: torsional chiral magnetic effect  and negative thermal magnetoresistivity . Order parameter textures, e.g., vortices and skyrmions, generate emergent magnetic fields directly acting on Weyl fermions. I will demonstrate that equilibrium mass flow in superfluid 3He-A with skyrmion texture is attributed to the chiral anomaly induced by a torsional magnetic field . In addition, an emergent magnetic field induced by vortex textures in Weyl superconductors results in the negative magnetoresistivity of longitudinal thermal currents along vortices. The chiral anomaly contribution of thermal conductivity exhibits characteristic temperature dependence, which can be a smoking-gun signature of Weyl superconductivity.
 Y. Ishihara, T. Mizushima, A. Tsuruta, and S. Fujimoto, Phys. Rev. B 99, 024513 (2019).
 T. Kobayashi, T. Matsushita, T. Mizushima, A. Tsuruta, and S. Fujimoto, Phys. Rev. Lett. 121, 207002 (2018).