Revision 1

Accepted · first revision · record

Title: Superconducting gap structure of AV3Sb5
Plain: Whether the superconducting gap of these kagome metals vanishes somewhere on the Fermi surface, and whether it changes sign, is disputed.
Precise: Determine the gap structure of AV3Sb5 superconductors (nodal or nodeless, sign-changing or not) and its dependence on the charge-density-wave state, for example under pressure where $T_{c}$ has two domes. An answer is penetration depth, thermal conductivity and phase-sensitive measurements on the same crystals, with controlled disorder to test sign change.
Settled by: Penetration depth with electron-irradiation series and thermal conductivity, plus quasiparticle interference sign tests.
Kind: well-posed
Answer type: identification
References: (empty)
Literature status: contested
Status note: Penetration depth with controlled electron irradiation (2023) points to a nodeless sign-preserving gap; other reports infer nodes.
Posed since: 2021