Asymmetric Josephson Effect in WTe2 Weyl Semimetal

WTe₂ is predicted to be Type-II Weyl semimetal, hosting Weyl nodes at the contact of electron and hole pockets in a momentum space. We studied electronic transport properties of the Josephson effects mediated by WTe2 Weyl semimetal. Proximity Josephson junctions were fabricated by depositing a pair of superconducting electrodes on exfoliated WTe2 layers. Perpendicular magnetic field dependence of Josephson critical current, I_c(B), (so-called Fraunhofer pattern) exhibited anomalous behaviors: 1) Slow decay of I_c lobes as B increases indicates that the transport is dominated by edge channels of WTe₂ layer. 2) Asymmetric Fraunhofer pattern, i.e. I_c(B)≠I_c(-B), suggests asymmetric Fermi velocity of each edge channel due to the inversion symmetry breaking of WTe₂.