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Title: Anomalous scaling of Δ C versus T c in the Fe-based superconductors: the $${S}_{\pm }$$-wave pairing state model

The strong power law behavior of the specific heat jump $${\rm{\Delta }}C\;$$ versus T c $$({\rm{\Delta }}C/{T}_{{\rm{c}}}\sim {T}_{{\rm{c}}}^{\alpha },\alpha \approx 2)$$, first observed by Bud'ko et al (2009 Phys. Rev. B 79 220516), has been confirmed with several families of the Fe-based superconducting compounds with various dopings. We tested a minimal two band BCS model to understand this anomalous behavior and showed that this non-BCS relation between $${\rm{\Delta }}C\;$$ versus T c is a generic property of the multiband superconducting state paired by a dominant interband interaction ($${V}_{\mathrm{inter}}\gt {V}_{\mathrm{intra}}$$) reflecting the relation $$\frac{{{\rm{\Delta }}}_{{\rm{h}}}}{{{\rm{\Delta }}}_{{\rm{e}}}}\sim \sqrt{\frac{{N}_{{\rm{e}}}}{{N}_{{\rm{h}}}}}$$ near T c, as in the $${S}_{\pm }$$-wave pairing state. We also found that this $${\rm{\Delta }}C\;$$ versus T c power law can continuously change from the ideal BNC scaling to a considerable deviation by a moderate variation of the impurity scattering rate $${{\rm{\Gamma }}}_{0}$$ (non-pair-breaking). Finally, as a result, our model provides a consistent explanation why the electron-doped Fe-based superconductors follow the ideal BNC scaling very well while the hole-doped systems often show varying degree of deviations.
Authors:
 [1] ;  [2]
  1. Chonnam National Univ., Kwangju (Korea). Dept. of Physics
  2. Univ. of Florida, Gainesville, FL (United States). Dept. of Physics
Publication Date:
OSTI Identifier:
1254478
Grant/Contract Number:
FG02-86ER45268; 2013-R1A1A2-057535
Type:
Accepted Manuscript
Journal Name:
New Journal of Physics
Additional Journal Information:
Journal Volume: 18; Journal Issue: 2; Journal ID: ISSN 1367-2630
Publisher:
IOP Publishing
Research Org:
Univ. of Florida, Gainesville, FL (United States)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS Fe-based superconductors; specific heat jump versus Tc,BNC scailing, S±-pairing state, two band model