Fig. 2: Zero-field superconducting properties and out-of-plane anisotropy of CsV3Sb5.
From: Violation of emergent rotational symmetry in the hexagonal Kagome superconductor CsV3Sb5
a DC magnetic susceptibility χ of our CsV3Sb5 single crystal measured under zero-field-cooled and field-cooled conditions. The demagnetization factor of 0.88 estimated from the sample shape has been considered. The inset shows the temperature derivative of zero-field-cooled χ, showing a sharp superconductive transition at the critical temperature Tc = 2.8 K with a full-width of half-maximum of less than 0.1 K. b Zero-field electronic specific heat of CsV3Sb5. The sharp jump at Tc again indicates a high quality of the sample. The temperature dependence is clearly different from the prediction of the standard BCS theory (dotted curve)3. c Upper critical field Hc2 along the a (pink squares), a* (blue circles), and c axes (green triangles). The inset shows the out-of-plane anisotropy Γ ≡ Hc2∥a/Hc2∥c (pink squares) and \({H}_{{{{{{{{\rm{c2}}}}}}}}\parallel {a}^{*}}/{H}_{{{{{{{{\rm{c2}}}}}}}}\parallel c}\) (blue circles). This quantity ranges from 9 to 11.5, indicative of the Q2D nature of superconductivity. d Polar field-angle θ dependence of Hc2 at 1.16 K in the ac (pink squares) and a*c planes (blue circles). Both data sets are well fitted by using an anisotropic mass model3 indicated by the dotted curves. The fit yields the anisotropy parameter of 10.4 for the ac plane and 10.5 for the a*c plane. The inset is an enlarged view near θ = 90∘.
