Nodes vs. minima in the energy gap of iron-pnictides from field-induced anisotropy

Abstract

We develop the formalism for computing the oscillations of the specific heat and thermal transport under rotated magnetic field in multiband superconductors with anisotropic gap and apply it to iron-pnictides. We show that these oscillations change sign at low temperatures and fields, which strongly influences the conclusions about the gap structure based on experiment. We find that recent measurements of the specific heat oscillations indicate that the iron-based superconductors possess an anisotropic gap with deep minima or nodes close to the line connecting electron and hole pockets. We make predictions for the behavior of the thermal conductivity that will help distinguish between these cases.

arXiv comment4+3 pages, published version with supplement

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• Anisotropic Structure of the Order Parameter in FeSe0.45Te0.55 Revealed by Angle Resolved Specific Heat
• Theory of quasiparticle vortex bound states in Fe-based superconductors: application to LiFeAs
• Transport properties of 3D extended s-wave states in Fe-based superconductors
• ${}^{75}$As NMR of Ba(Fe${}_{0.93}$Co${}_{0.07}$)${}_2$As${}_2$ in High Magnetic Field
• Quasiclassical description of a superconductor with a spin density wave
• Field-angle-resolved anisotropy in superconducting CeCoIn5 using realistic Fermi surfaces
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• Effects of the vortices and impurities on the nuclear spin relaxation rate in iron-based superconductors
• Role of Fermi surface anisotropy in the study of gap anisotropy using magnetic-field-angle dependence of thermal oscillations in AyFe2-xSe2 superconductors
• Quasiclassical analysis of vortex lattice states in Rashba noncentrosymmetric superconductors