Superconductors with broken inversion symmetry have offered a rich playground to explore unconventional superconductivity and/or non-trivial functionalities. One of the archetypal phenomena in such superconductors is the superconducting rectification effect, which has been observed as nonreciprocal resistance in the superconducting transition region around the critical temperature (T_c) [1] or superconducting diode effect [2], i.e., nonreciprocal superconducting critical current, in the fully superconducting region. Recently, various mechanisms for these phenomena have been discussed among Rashba spin-orbit interaction [3], asymmetric pinning potential of vortices [4], and surface or edge barrier effect [5], depending on the materials and measurement system of interests. Although the nonreciprocal resistance around T_c and the superconducting diode effect should be related through the common origin, the link between these two phenomena has not been explicitly addressed to date probably because the broadness of resistive transition around T_c generally impedes the magnitude of critical current density under magnetic fields.

In this talk, we report that tellurium doped iron selenide Fe(Se,Te) provides a good platform for the comprehensive study of the superconducting rectification effect. Thanks to its high superconducting critical parameters, such as T_c, critical field, and critical current, and the strong spin-orbit interaction, we demonstrated both the superconducting diode effect and nonreciprocal resistance in a wide range of magnetic field and temperature in a superconducting Fe(Se,Te)/FeTe heterostructure. From these data set, it was revealed that the nonreciprocal coefficient of the resistance, which is strongly enhanced around T_c , and rectification efficiency of the critical current exhibit a scaling relationship regardless of applied magnetic field and temperature. Our results point out the important role of the spin-orbit interaction on the asymmetric pinning potential of vortices for emergence of supercurrent rectification [6].

[1] J. E. Villegas et al., Science 302, 1188 (2003). [2] F. Ando et al., Nature 584, 373 (2020). [3] A. Daido, Y. Ikeda, and Y. Yanase, Phys. Rev. Lett. 128, 037001 (2022). [4] Y. M. Itahashi et al., Sci. Adv. 6, eaay9120 (2020). [5] Y. Hou et al., Phys. Rev. Lett. 131, 027001 (2023). [6] Y. Kobayashi, J. Shiogai et al., submitted.