Josephson Junctions of Weyl Semimetal WTe2 Induced by Spontaneous Nucleation of PdTe Superconductor

We report on the fabrication of Josephson junction devices with weak links utilizing the Weyl and higher-order topological semimetal WTe2. We show that the WTe2/Pd contact annealed at a low temperature of 80 °C did not exhibit superconducting properties because neither WTe2 nor Pd are superconductors in the ground state. Upon 180 °C annealing, spontaneous formation of superconducting PdTe due to Pd diffusion enabled us to obtain the interface between WTe2 and superconductor suitable for the Josephson junction. This result is a facile technique to make a Josephson junction and induce Cooper pairs into topological telluride semimetals.