Edge superconductivity in multilayer WTe2 Josephson junction

Ce Huang; Awadhesh Narayan; Enze Zhang; Xiaoyi Xie; Linfeng Ai; Shanshan Liu; Changjiang Yi; Youguo Shi; Stefano Sanvito; Faxian Xiu

doi:10.1093/nsr/nwaa114

Edge superconductivity in multilayer WTe₂ Josephson junction

Natl Sci Rev. 2020 May 30;7(9):1468-1475. doi: 10.1093/nsr/nwaa114. eCollection 2020 Sep.

Authors

Affiliations

¹ State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China.
² SSCU, Indian Institute of Science, Bengaluru 560012, India.
³ Institute of Physics and Beijing National Laboratory for Condensed Matter Physics, Chinese Academy of Sciences, Beijing 100190, China.
⁴ School of Physics, AMBER and CRANN Institute, Trinity College, Dublin 2, Ireland.

Abstract

WTe₂, as a type-II Weyl semimetal, has 2D Fermi arcs on the (001) surface in the bulk and 1D helical edge states in its monolayer. These features have recently attracted wide attention in condensed matter physics. However, in the intermediate regime between the bulk and monolayer, the edge states have not been resolved owing to its closed band gap which makes the bulk states dominant. Here, we report the signatures of the edge superconductivity by superconducting quantum interference measurements in multilayer WTe₂ Josephson junctions and we directly map the localized supercurrent. In thick WTe₂ ([Formula: see text], the supercurrent is uniformly distributed by bulk states with symmetric Josephson effect ([Formula: see text]). In thin WTe₂ (10 nm), however, the supercurrent becomes confined to the edge and its width reaches up to [Formula: see text]and exhibits non-symmetric behavior [Formula: see text]. The ability to tune the edge domination by changing thickness and the edge superconductivity establishes WTe₂ as a promising topological system with exotic quantum phases and a rich physics.

Keywords: Josephson junction; WTe2; Weyl semimetal; edge superconductivity; non-symmetric effect.