Two superconducting phases induced at point contacts on the Weyl semimetal TaAs

Tip-induced superconductivity commonly existing in the family of transition-metal dipnictides MP n 2 *

“…The points with relatively higher 017304-3 upper critical fields fall into the universal trend of H c2 (0) ∝ T 1.5 c (thicker solid line). [27] It is worth noting that the TISC has been realized on various topological materials, [19][20][21][22][23][24][25][26][27]45] whereas it has been rarely reported on the conventional metals, suggesting that the TISC on topological materials maybe closely related to their topological properties and share the same origin. That is to say, such TISC on MPn 2 family most likely originates from the interface coupling between the tips and samples.…”

“…Intensive theoretical and experimental researches have been carried out in searching for topological superconductors (TSCs), e.g., charge carrier doping, high pressure, and proximity effect. [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Very recently, tip-induced superconductivity (TISC) was observed in a variety of non-superconducting topological semimetals by means of pointcontact (PC), [19][20][21][22][23][24][25][26][27] which had aroused great enthusiasm in the research of topological superconductivity. So far, superconductivity has been induced in various topological materials, however, whether these phenomena share a common mechanism is still in debate.…”

Applications of point-contact spectroscopy in the study of topological materials

“…目前已经证实的可以使用点接触针尖诱导超导的 拓扑半金属材料还包括具有线节点的ZrSiS [127] 、Weyl 半金属TaP [115] 以及弱拓扑绝缘体TaAs 2 , NbAs 2 和 NbSb 2 [128] 等, 其中可以使用磁性针尖诱导超导的拓扑 材料包括TaP [115] , TaAs [114,119] . 另外, 某些形态的Bi本 身可能是超导体 [132] , 而点接触作为一种局部测量手段 有可能探测到夹杂在Bi样品中的超导团簇的信号 [130] .…”

“…[19,134,135] . 然而, 在实现针尖诱导 超导的拓扑半金属材料中, 有些在很高的压力作用下 也没有出现超导, 比如WC, TaAs以及TaAs 2 等 [118] ; 有 些在高压下可以转变为超导体, 但是出现超导的临界 压力一般比较高, 比如TaP在30 GPa出现超导电性 [136] , [119] . 根据H c2 (0)与超导相干 长度之间的关系可以得到干净极限下弱耦合超导体的 H c2 (0)与T c 之间的近似平方关系: 移对称性形成量子阱, 使表面态发生剧烈的重构 [138][139][140][141] , 甚至形成表面二维电子气 [142,143] .…”

Formation of tungsten carbide by focused ion beam process: A route to high magnetic field resilient patterned superconducting nanostructures

“…There has been a number of efforts to find exotic superconductors (e.g FFLO, spin-triplet, topological ) in recent past which might compatible with relatively high magnetic field. Several methods including metal intercalation between layers of a material [5,6], applying high pressure, hard and soft tip contact [7][8][9] and interface between two materials [10,11] has been tried for achieving this. In this paper, we point out an emerging class of materials, composed of Ga and a heavy metal carbide, fabricated using FIB which are undoubtedly granular and highly disordered, but with H c2 significantly above the Pauli limit.…”