Intrinsic anisotropy of The superconductivity in FeSe_1-xTe_x (x 0.6) observed by specific heat in magnetic fields

Low-temperature specific heat measurements in various magnetic fields parallel and perpendicular to The c-axis for annealed single crystals of The iron-chalcogenide superconductor FeSe_1-xTe_x have revealed that The anisotropy of The enhancement of The residual electronic- specific-heat-coefficient in The ground state by The application of magnetic field, namely, The anisotropy of The upper critical field, H_c2, is 2.2 for x 0.6, which is different from The anisotropy of H_c2 estimated from The resistivity measurements in non-annealed single crystals of x 0.6 [Khim et al. 2010 Phys. Rev. B 81 184511]. It appears that The anisotropy of H_c2 strongly depends on The content of excess iron included in a crystal.