Nodeless Superconductivity in Kagome Metal CsV₃Sb₅ with and without Time Reversal Symmetry Breaking

Abstract

The kagome metal CsV3Sb5 features an unusual competition between the charge-density-wave (CDW) order and superconductivity. Evidence for time reversal symmetry breaking (TRSB) inside the CDW phase has been accumulating. Hence, the superconductivity in CsV3Sb5 emerges from a TRSB normal state, potentially resulting in an exotic superconducting state. To reveal the pairing symmetry, we first investigate the effect of nonmagnetic impurity. Our results show that the superconducting critical temperature is insensitive to disorder, pointing to conventional s-wave superconductivity. Moreover, our measurements of the self-field critical current (I c,sf ), which is related to the London penetration depth, also confirm conventional s-wave superconductivity with strong coupling. Finally, we measure I c,sf where the CDW order is removed by pressure and superconductivity emerges from the pristine normal state. Our results show that s-wave gap symmetry is retained, providing strong evidence for the presence of conventional s-wave superconductivity in CsV3Sb5 irrespective of the presence of the TRSB.

Anomalous Hall effect and two-dimensional Fermi surfaces in the charge-density-wave state of kagome metal RbV3Sb5

“…However, both KV 3 Sb 5 and RbV 3 Sb 5 should also be investigated to build an overall picture to understandthis family of V-based kagome superconductors. For instance, a µSR experiment shows that the superconducting energy gap can be tuned from nodal at ambient pressure to nodeless under pressure in RbV 3 Sb 5 and KV 3 Sb 5 [32], but this tunability is absent in CsV 3 Sb 5 , where the gap is found to be nodeless over a large pressure range [37,38]. Whether the observed nodal gap is related to TRSB needs to be addressed.…”

Charge-loop current order and Z3 nematicity mediated by bond order fluctuations in kagome metals

“…1 b, which is the even-parity modulation in the hopping integral (=real) 6 – 12 . Below the BO transition temperature T BO , superconductivity (SC) with highly anisotropic gap emerges for A = Cs 13 , 14 , and the gap structure changes to isotropic by introducing impurities. Also, nodal to nodeless crossover is induced by the external pressure in A = Rb,K 15 .…”

Insight into the quantum anomalous Hall states in two-dimensional kagome Cr3Se4 and Fe3S4 monolayers

“…46,47 In this work, we investigate Cr 3 Se 4 and Fe 3 S 4 monolayers with kagome structures, which is ignited by the discovery of kagome bulk materials ATM 3 X 5 (A = K, Cs, Rb), which are identified to hold excellent physical properties, such as superconductivity, large anomalous Hall conductivity, and nontrivial topology. [48][49][50] However, most TM 3 X 5 monolayers have been determined to be dynamically unstable. Alternatively, we further eliminated the X atom at the center of hexagons to form…”