Two-dimensional superconductors with intrinsic p-wave pairing or nontrivial band topology

Abstract

Over the past fifteen years, tremendous efforts have been devoted to realizing topological superconductivity in realistic materials and systems, predominately propelled by their promising application potentials in faulttolerant quantum information processing. In this article, we attempt to give an overview on some of the main developments in this field, focusing in particular on two-dimensional crystalline superconductors that possess either intrinsic p-wave pairing or nontrivial band topology. We first classify the three different conceptual schemes to achieve topological superconductor (TSC), enabled by real-space superconducting proximity effect, reciprocal-space superconducting proximity effect, and intrinsic TSC. Whereas the first scheme has so far been most extensively explored, the subtle difference between the other two remains to be fully substantiated. We then move on to candidate intrinsic or p-wave superconductors, including Sr 2 RuO 4 , UTe 2 , Pb 3 Bi, and graphenebased systems. For TSC systems that rely on proximity effects, the emphases are mainly on the coexistence of superconductivity and nontrivial band topology, as exemplified by transition metal dichalcogenides, cobalt pnictides, and stanene, all in monolayer or few-layer regime. The review completes with discussions on the three dominant tuning schemes of strain, gating, and ferroelectricity in acquiring one or both essential ingredients of the TSC, and optimizations of such tuning capabilities may prove to be decisive in our drive towards braiding of Majorana zero modes and demonstration of topological qubits.

Toward large-scale, ordered and tunable Majorana-zero-modes lattice on iron-based superconductors

“…The interesting topological band structure puts FeTe 0.55 Se 0.45 a promising candidate for realizing MZM [81]. This type of Majorana platform has been referred to as connate [75,82] or reciprocal-space superconducting proximity effectinduced topological superconductor [83]. The topological superconductivity on the surface serves as a consequence of conventional bulk superconductivity and the non-trivial topology on some part of the band structures (figure 1(c)).…”

Controllable superconducting to semiconducting phase transition in topological superconductor 2M-WS2

“…Approaches for achieving topological superconductors can be divided into three categories [4]: (i) real-space superconducting proximity effectinduced topological superconductivity, exemplified by Bi 2 Te 3 /NbSe 2 [5]; (ii) reciprocal-space superconducting proximity effect-induced topological superconductivity, as observed in doped threedimensional topological insulators [6,7] and ironbased superconductors [8][9][10][11][12]; (iii) intrinsic topological superconductivity, as seen in Sr 2 RuO 4 [13], UTe 2 [14], and Pb 3 Bi [15]. In recent years, substantial progress has been made in exploring realistic material systems that can support robust topological superconductivity [16,17], and researchers have also been working to develop the theoretical foundation for constructing topological qubits as critical components [18][19][20].…”

Majorana zero mode and its lattice construction in iron-based superconductors

“…有趣的拓扑能带结构使FeTe 0.55 Se 0.45 成为马 约拉纳零能模的可能承载平台 [63,[69][70][71][72] . FeTe 0.55 Se 0.4 的拓扑超导电性来源于拓扑表面态与体态近邻 的超导电性, 因此也被称作倒易空间近邻效应.…”