Chirality Josephson current due to a novel quantum anomaly in Weyl semimetals

DIPC Seminars

Speaker

Björn Trauzettel, Würzburg University, Germany

When

2019/09/03
14:00

Place

Donostia International Physics Center

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We study Josephson junctions based on inversion-asymmetric but time-reversal symmetric Weyl semimetals under the influence of Zeeman fields. We find that, due to distinct spin textures, the Weyl nodes of opposite chirality respond differently to an external magnetic field. Remarkably, a Zeeman field perpendicular to the junction direction results in a phase shift of opposite sign in the current-phase relations of opposite chirality, similar to a phi_0 junction. This leads to a finite chirality Josephson current (CJC) even in the absence of a phase difference across the junction. In the long junction and zero temperature limit, the CJC embodies a novel quantum anomaly of Goldstone bosons at a phase difference of pi which is associated with a Z2 symmetry at low energies. We argue that it can be detected experimentally via an anomalous Fraunhofer pattern. Host: Sebastian Bergeret