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 (⁠|$\sim 60{\rm{\ nm}})$|⁠, the supercurrent is uniformly distributed by bulk states with symmetric Josephson effect (⁠|$| {I_c^ + ( B )} | {=} | {I_c^ - ( B )} |\ $|⁠). In thin WTe₂ (10 nm), however, the supercurrent becomes confined to the edge and its width reaches up to |$1.4{\rm{\ \mu m\ }}$|and exhibits non-symmetric behavior |$| {I_c^ + ( B )} | \ne | {I_c^ - ( B )} |$|⁠. 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.

中文翻译：

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多层WTe2约瑟夫森结中的边缘超导性

WTe ₂作为II 型外尔半金属，在(001) 表面上具有2D 费米弧，在其单层中具有1D 螺旋边缘状态。这些特征最近在凝聚态物理中引起了广泛关注。然而，在块体和单层之间的中间状态中，由于其闭合带隙使块体状态占主导地位，边缘态尚未解决。在这里，我们通过多层 WTe ₂ Josephson 结中的超导量子干涉测量报告了边缘超导性的特征，并且我们直接映射了局部超电流。在厚的 WTe ₂ ( ⁠|$\sim 60{\rm{\ nm}})$|⁠ 中，超电流由具有对称约瑟夫森效应的体态均匀分布⁠|$| {I_c^ + ( B )} | {=} | {I_c^ - ( B )} |\ $|⁠ )。然而，在薄的 WTe ₂ (10 nm) 中，超电流被限制在边缘，其宽度达到|$1.4{\rm{\ \mu m\ }}$| 并表现出非对称行为|$| {I_c^ + ( B )} | \n | {I_c^ - ( B )} |$|⁠。通过改变厚度和边缘超导性来调整边缘控制的能力使 WTe ₂成为具有奇异量子相和丰富物理特性的有前途的拓扑系统。