Fig. 4: Temperature evolution of in-plane superconducting anisotropy in CsV₃Sb₅.

Here, in-plane anisotropy of H_c2 deduced from the field-angle dependence of the specific heat at various temperatures are shown. The measurement field H_meas is close to the mid-point of the SC transition at each temperature. a In-plane H_c2 anisotropy at 2.4 K. As explained in the text, the anisotropy δH_c2 is evaluated from the specific heat anisotropy δC/T using the relation δH_c2 = −α⁻¹δC/T, where α = (1/T)(dC/dH) is the slope of the C(H)/T vs. H curve at the same temperature. The corresponding δC/T values are shown using the right vertical axis. The curves represent the result of sinusoidal fitting using six and twofold oscillations. Each data point is obtained by averaging raw C data for typically 120 s and the error bar represents standard errors of the averaged data set. b Same plot but for the data at 1.6 K. c Same plot but for the data at 0.8 K.