Superconducting gap evolution in overdoped BaFe2(As1-xPx)(2) single crystals through nanocalorimetry
Number of Authors: 6
2015 (English)In: Physical Review B. Condensed Matter and Materials Physics, ISSN 1098-0121, E-ISSN 1550-235X, Vol. 91, no 24, 245142Article in journal (Refereed) Published
We report on specific heat measurements on clean overdoped BaFe2(As1-xPx)(2) single crystals performed with a high resolution membrane-based nanocalorimeter. A nonzero residual electronic specific heat coefficient at zero temperature gamma(r) = C/T backslash(T -> 0) is seen for all doping compositions, indicating a considerable fraction of the Fermi surface ungapped or having very deep minima. The remaining superconducting electronic specific heat is analyzed through a two-band s-wave alpha model in order to investigate the gap structure. Close to optimal doping we detect a single zero-temperature gap of Delta(0) similar to 5.3 meV, corresponding to Delta(0)/k(B)T(c) similar to 2.2. Increasing the phosphorus concentration x, the main gap reduces till a value of Delta(0) similar to 1.9 meV for x = 0.55 and a second weaker gap becomes evident. From the magnetic field effect on gamma(r), all samples however show similar behavior [gamma(r)(H) -gamma(r)(H = 0) proportional to H-n, with n between 0.6 and 0.7]. This indicates that, despite a considerable redistribution of the gap weights, the total degree of gap anisotropy does not change drastically with doping.
Place, publisher, year, edition, pages
2015. Vol. 91, no 24, 245142
IdentifiersURN: urn:nbn:se:su:diva-118947DOI: 10.1103/PhysRevB.91.245142ISI: 000356474500006OAI: oai:DiVA.org:su-118947DiVA: diva2:842972