Superconducting specific-heat jumpΔCel∝Tcβ(β≈2)forK

Quasiparticle interference in multiband superconductors with strong coupling

“…The underlying reason is the multiband character of the Fermi surfaces in the FeBSs. In this case the order parameter may change sign due to impurities, as was demonstrated theoretically [26][27][28] and experimentally [29] with doping either to d-wave symmetry [30][31][32][33] or a change of sign [34]. Therefore, a universal tool to ascertain the pairing symmetry is much needed.…”

Multiple phase transitions in Pauli-limited iron-based superconductors

“…This method can be used to find phase transition e.g. in multiband superconductors like IBSC [33][34][35][36] or MgB 2 [37,38]. Specific heat measurements have been also successfully used to investigate the FFLO phase in heavy-fermion systems [7,8,11] and organic superconductors [14], where the peaks, deep in the superconducting state in the LTHM regime, have been interpreted as phase transitions from BCS to FFLO state.…”

Universal V-shaped temperature-pressure phase diagram in the iron-based superconductorsKFe2As2,RbFe2As2, andTafti1, Ouellet2, Juneau-Fecteau3 et al. 2015Phys. Rev. B

“…Laser ARPES experiments suggest a s ± state with eight line nodes on the ξ band and no nodes on the α and β bands. 13,14 By contrast, bulk measurements of thermal conductivity, 15,16 , heat capacity 17,18 and penetration depth 19,20 point to a d-wave state, with four line nodes on each of the Γ-centered Fermi pockets (α, ξ, and β).…”