Superconducting Diode Effects: Mechanisms, Materials and Applications

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 is proposed that intrinsic SDEs are closely linked to various exotic superconducting states, such as the Fulde–Ferrell–Larkin–Ovchinnikov 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 the 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, the review summarizes the observed rectification efficiency of SDE devices and discusses future research directions in this rapidly developing field.