Interface Superconductivity in a Dirac Semimetal NiTe2

Abstract

We experimentally investigated charge transport through a single planar junction between a NiTe (Formula presented.) Dirac semimetal and a normal gold lead. At milli-Kelvin temperatures, we observe non-Ohmic (Formula presented.) behavior resembling Andreev reflection at a superconductor–normal metal interface, while NiTe (Formula presented.) bulk remains non-superconducting. The conclusion on superconductivity is also supported by the suppression of the effect by temperature and magnetic field. In analogy with the known results for Cd (Formula presented.) As (Formula presented.) Dirac semimetal, we connect this behavior with interfacial superconductivity due to the flat-band formation at the Au-NiTe (Formula presented.) interface. Since the flat-band and topological surface states are closely connected, the claim on the flat-band-induced superconductivity is also supported by the Josephson current through the topological surface states on the pristine NiTe (Formula presented.) surface. We demonstrate the pronounced Josephson diode effect, which results from the momentum shift of the topological surface states of NiTe (Formula presented.) under an in-plane magnetic field.