Superconducting Diode Effects: Mechanisms, Materials and Applications

Abstract: Superconducting diode effects (SDEs) generally emerge in superconducting systems where both time-reversal and inversion symmetries are broken, showing nonreciprocal current characteristics: nondissipative in one direction and ohmic in the opposite. Since the discovery of the SDEs by Ando et al. in the noncentrosymmetric superconductor [Nb/V/Ta]n in 2020, notable progress has been achieved on both the theoretical and experimental fronts. It has been proposed that intrinsic SDEs are closely linked to various exotic superconducting states, such as the Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) state, topological superconductivity, and chiral superconductivity. Recently, SDEs have emerged as important experimental tools for detecting symmetry breaking in exotic superconducting states. This advancement not only enhances our understanding of the fundamental nature of SDEs but also opens new possibilities for their applications in superconducting physics and related fields. This review focuses on the recent experimental progress in the observation of the SDEs and discusses their primary mechanisms from the perspective of material properties and symmetry breaking. Finally, we summarize the observed rectification efficiency of SDE devices and discuss future research directions in this rapidly developing field.