Determine the superconducting order-parameter symmetry of CsV3Sb5

Determine the symmetry of the superconducting order parameter in CsV3Sb5 and characterize its relationship to the charge-density-wave state from which superconductivity emerges.

Background

The paper situates CsV3Sb5 within the AV3Sb5 family, whose phase diagrams contain both charge-density-wave order and low-temperature superconductivity. Experimental studies have reported differing conclusions about the superconducting gap, including nodeless anisotropic behavior and possible time-reversal-symmetry breaking. The authors emphasize that existing spectroscopic and thermodynamic probes generally cannot distinguish among several fully gapped candidate states, including s-wave, sign-changing s±, chiral d-wave, and chiral p-wave states.

Although the paper uses order-parameter relaxation and ultrasonic attenuation to constrain the role of elastic and inelastic scattering, it does not uniquely determine the superconducting symmetry or fully resolve how superconductivity is related to the charge-density-wave state.

References

Although some experiments favor a nodeless, anisotropic superconducting gap, the symmetry of the superconducting order parameter, and its relationship to the CDW state from which it emerges, remains unresolved.

— Out-of-equilibrium relaxation dynamics of the superconducting order parameter in CsV$_3$Sb$_5$  (2609.11686 - Shragai et al., 10 Sep 2026) in Introduction

While this scenario provides a possible route to compatibility between our observation and an unconventional order parameter, it remains to be determined whether the required form of disorder protection is realized in CsV$_3$Sb$_5$.

— Out-of-equilibrium relaxation dynamics of the superconducting order parameter in CsV$_3$Sb$_5$  (2609.11686 - Shragai et al., 10 Sep 2026) in Discussion, final paragraph