Superconductivity with twofold symmetry in Bi ₂ Te ₃ /FeTe _0.55 Se _0.45 heterostructures

Abstract

Superconductivity with twofold symmetry is observed by STM in Bi2Te3/FeTe0.55Se0.45 heterostructures.

Linear correlation between the c-axis lattice constant and superconducting critical temperature in FeSe0.5Te0.5 thin films

“…The 11 type iron-based superconductor (FeSe 1−x Te x ) have drawn much attention in basic research and applications, especially in superconducting mechanism exploration [1,2], because of their simplest crystal structure and non-toxic properties [3,4]. The bulk FeSe showed a superconducting transition temperature (T c ) of about 8K [5], and the superconductivity onset in α-FeSe was reported to attain a broad maximum of 37 K under 7 GPa hydrostatic pressure [6].…”

The direction of the d-vector in a nematic triplet superconductor

“…Note that D x 4 -pairing leads to nodal SC gap, protected by the remaining mirrow symmetry about y (sending x x), while D y 4 -pairing could become fully gapped in the presence of warping effect in the normal state band structure [19]. While the nematicity is observed by various probes, the identified direction of the d-vector varies [17,[20][21][22][23][24][25]. Theoretically [26], direct visualization of the d-vector is possible by quasi-particle interference (QPI) [27] and STM: the leading peak momentum in QPI at sub-gap energies should be along the d-vector, and the STM profile of the vortex at low energies should be elongated also along the d-vector.…”

Proximity-induced superconductivity in a topological crystalline insulator

“…For example, a single unit cell thick film of SnTe is shown to exhibit room-temperature ferroelectricity 14 , while a bulk single crystal of (Pb,Sn)Se is reported to host 1D edge modes propagating along step edges 15,17 . Theory predicts that if a TCI undergoes a superconducting transition, a new topological superconducting phase could emerge [18][19][20][21] distinct from that in proximitized Z2 topological insulators Bi2(Se,Te)3 [22][23][24][25][26][27][28] . The difference is rooted in the unique mirror symmetry protection and multiple Dirac fermions present at the surface of TCIs, which are expected to facilitate novel phenomena emerging at the surface.…”

“…An alternative method to induce superconductivity in a material, without introducing chemical disorder, could entail using the proximity effect 35 . This approach typically involves deposition or exfoliation of thin films on top of superconducting substrates, and it has been widely applied to Z2 topological insulators [22][23][24][25][26][27][28] .…”