Flat band superconductivity in type-II Weyl-semimetal WTe2 induced by a normal metal contact

Artem Kononov, Martin Endres, Gulibusitan Abulizi, Kejian Qu, Jiaqiang Yan, David G. Mandrus, Kenji Watanabe, Takashi Taniguchi, Christian Schönenberger

Published 2020-07-09Version 1

WTe$_2$ is a material with rich topological properties: it is a 2D topological insulator as a monolayer and a Weyl-semimetal and higher-order topological insulator (HOTI) in the bulk form. Inducing superconductivity in topological materials is a way to obtain topological superconductivity, which lays at the foundation for many proposals of fault tolerant quantum computing. Here, we demonstrate the emergence of superconductivity at the interface between WTe$_2$ and the normal metal palladium. The superconductivity has a critical temperature of about 1.2 K. By studying the superconductivity in perpendicular magnetic field, we obtain the coherence length and the London penetration depth. These parameters hint to a possible origin of superconductivity due to the formation of flat bands. Furthermore, the critical in-plane magnetic field exceeds the Pauli limit, suggesting a non-trivial nature of the superconducting state.