Evidence for s±-wave pairing symmetry in LiFeAs from its low-temperature specific heat
Abstract
We report specific heat capacity measurements on a LiFeAs single crystal at temperatures down to 400 mK and magnetic fields up to 9 T. A small specific heat jump at Tc and finite residual density of states at T=0 K in the superconducting (SC) state indicate that there are strong unitary scatterers that lead to states within the SC gap. A sublinear magnetic field dependence of the Sommerfeld coefficient γ(H) at T=0 K is equally well fitted by both a nodal d-wave gap as well as a sign changing multiband s±-wave gap. When impurity effects are taken into account, however, the linear temperature dependence of the electronic specific heat Cel/T at low temperatures argues against a nodal d-wave superconducting gap. We conclude that the SC state of LiFeAs is most compatible with the multiband s±-wave SC state with the gap values Δsmall=0.46Δlarge.
- Publication:
-
Physical Review B
- Pub Date:
- May 2012
- DOI:
- 10.1103/PhysRevB.85.180505
- Bibcode:
- 2012PhRvB..85r0505J
- Keywords:
-
- 74.70.Xa;
- 74.25.Bt;
- 74.20.Rp;
- Thermodynamic properties;
- Pairing symmetries