Effective six-band model and unconventional spin-singlet pairing in Kagome superconductor CsV₃Sb₅

Abstract

Recently synthesized Kagome compounds AV3Sb5 attract great attention due to the unusual coexistence of the topology, charge density wave, and superconductivity. In this work, based on the band structures for CsV3Sb5 in the pristine phase, we construct an effective six-band model for the low-energy processes; utilizing the random phase approximation on the effective six-band model, we show that the E1u ( p wave ) pairing dominates in the region of 0 < U < 0.32 eV, the A2g ( I wave ) in the region of 0.32 < U < 0.75 eV and the E2g ( d wave ) in the region of 0.75 < U < 1 eV. Considering that the correlation in AV3Sb5 is weak or intermediate, these results suggest that pairing symmetry is A2g ( I-wave ) in the CsV3Sb5, which can explain some recent experiments about pairing symmetry.

Commensurate-to-incommensurate transition of charge-density-wave order and a possible quantum critical point in pressurized kagome metal CsV3Sb5

“…10 for the complete phase diagram) 31,32 . Our results suggest that the superconductivity is sustained by the spin fluctuations at high pressures, which seems to be consistent with recent theoretical studies 36,38 . In passing, we also note that a new superconducting state arises above P ~15 GPa with the pressure further increasing 33,34 .…”

“…Although the high-pressure nuclear magnetic resonance (NMR) experiments suggested that the CDW undergoes an evolution to a new phase with a possible stripe-like CDW order with a unidirectional 4a 0 modulation in pressurized CsV 3 Sb 5 35 , information about pressure-dependent CDW fluctuations is still lacking, which is of much significance to clarify its interaction with superconducting symmetry. Besides the CDW fluctuations, spin fluctuations were also proposed to play an important role in the high-pressure superconducting phase 36,38 . But whether spin fluctuations exist or not and how they are affected by pressures are still unclear in the current stage.…”

Manipulating charge density wave state in kagome compound RbV3Sb5

“…2(c), the 2 × 2 modulation is clearly identified as the characteristic of the CDW phase, which is consistent with the previous studies. [13,[15][16][17][18] The dI/dV spectra taken on the Sb terminated plane is plotted in Fig. 2(d).…”

“…[12,13] AV 3 Sb 5 undergoes both of the superconductivity transition (T C =∼ 0.9 K-2.5 K) and the CDW (T CDW =∼ 78 K-103 K). [12][13][14] During the CDW transition, an in-plane unit-cell doubling with the 2 × 2 periodicity [13,[15][16][17][18] occurs, as also accompanied by a threedimensional 2 × 2 × 2/2 × 2 × 4 ordering [19,20] and a surface 1 × 4 superstructure. [15,21] It was considered that the CDW phase exhibits some complicated entanglement with the superconductivity transition.…”