Biaxial strain effect on Josephson supercurrent in a 2D Weyl semimetal

Based on the Weyl–Bogoliubov-de Gennes equation, we investigate the impact of biaxial strain on the Josephson supercurrent in a 2D Weyl semimetal Josephson junction, where the biaxial strain is induced by a piezoelectric film. It is shown that the current phase relation can be attenuated and non-monotonically modulated by the transverse and the longitudinal strain strength, respectively. When both are present, the subgap Andreev bound levels and the resulting Josephson supercurrent are sensitive to the potential energy and the length in the weak link region and the gate voltage (biaxial strain), and an enhancement or weakening of the supercurrent by shifting the Weyl nodes without requiring a magnetic or Zeeman term is induced. It is also revealed that the gate voltage (strain) can cause a supercurrent switch, where the cutoff gate voltage depends on the potential energy in the weak link region. The research also explores the temperature dependence of the supercurrent, noting a monotonic decrease and a logistic-like function with increasing temperature due to the thermal effect on subgap Andreev bound levels. The findings of this study are significant for the understanding of superconducting electronics in 2D Weyl semimetal and offering a new avenue for designing strain tunable quantum devices with all-electrical control.

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