Physics and Astronomy, Ames Laboratory
Journal or Book Title
Physical Review Letters
The temperature and magnetic field dependence of the in-plane thermal conductivity κ of the iron-arsenide superconductor Ba(Fe1−xCox)2As2 was measured down to T≃50 mK and up to H=15 T as a function of Co concentration x in the range 0.048≤x≤0.114. At H=0, a negligible residual linear term in κ/T as T→0 at all x shows that the superconducting gap has no nodes in the ab plane anywhere in the phase diagram. However, while the slow H dependence of κ(H) at T→0 in the underdoped regime is consistent with a superconducting gap that is large everywhere on the Fermi surface, the rapid increase in κ(H) observed in the overdoped regime shows that the gap acquires a deep minimum somewhere on the Fermi surface. Outside the antiferromagnetic-orthorhombic phase, the superconducting gap structure has a strongly k-dependent amplitude.
American Physical Society
Tanatar, Makariy A.; Reid, J.-Ph.; Shakeripour, H.; Luo, X. G.; Doiron-Leyraud, N.; Ni, Ni; Bud’ko, Sergey L.; Canfield, Paul C.; Prozorov, Ruslan; and Taillefer, Louis, "Doping Dependence of Heat Transport in the Iron-Arsenide Superconductor Ba(Fe1-xCox)(2)As-2: From Isotropic to a Strongly k-Dependent Gap Structure" (2010). Physics and Astronomy Publications. 700.