Distinction between critical current effects and intrinsic anomalies in the point-contact Andreev reflection spectra of unconventional superconductors

He Ge^{1, 2, †, ‡}, Wei Zhong-Xu^{1, 2, †}, Brisbois Jérémy^{3, †}, Jia Yan-Li^{1, 2}, Huang Yu-Long^{1, 2}, Zhou Hua-Xue^{1, 2}, Ni Shun-Li^{1, 2}, Silhanek Alejandro V³, Shan Lei^{1, 2, 4}, Zhu Bei-Yi¹, Yuan Jie¹, Dong Xiao-Li^{1, 2, 4}, Zhou Fang^{1, 2, 4}, Zhao Zhong-Xian^{1, 2, 4}, Jin Kui^{1, 2, 4}

(color online) Distinction between critical current effects and zero bias conductance peak. (a) d I / d V ( V ) spectra for an La_0.9Ce_0.1CuO₄ film with a critical temperature T c = 25 K at T = 1.8 K. (b) Evolution of d I / d V ( 0 ) (zero bias conductance) with the temperature, obtained from the d I / d V ( V ) spectra represented in panels (c) and (d). The experimental data is shown in gray, while fitting with the BTK model is represented by the red line. The inset in panel (b) shows the corresponding I(V) curve at T = 1.8 K.