Heat capacity measurement was performed on recently discovered, iron-based layered superconductors, namely, nondoped LaFePO and fluorine-doped LaFePO (LaFePO0.94F0.06). A relatively large electronic heat capacity coefficient (γ) of 10.6 mJ K-2 mol-1 and a small normalized heat capacity jump (ΔCp/γTc) of 0.29 at Tc = 3.3K were observed in LaFePO. LaFePO 0.94F0.06 had a smaller γ of 8.3 mJ K-2 mol-1 and a larger ΔCp/γTc of 0.44 at Tc = 5.8 K. These results indicate that these compounds have a strong electron-electron correlation and a large magnetic spin fluctuation, which are the signatures of unconventional superconductivity mediated by spin fluctuation.
ASJC Scopus subject areas
- Physics and Astronomy(all)