Current-Driven Magnetization Switching for Superconducting Diode Memory

Abstract

Stacking superconductors (SC) with ferromagnetic materials (FM) significantly impact superconductivity, enabling the emergence of spin-triplet states and topological superconductivity. The tuning of superconductivity in SC-FM heterostructure is also reflected in the recently discovered superconducting diode effect, characterized by nonreciprocal electric transport when time and inversion symmetries are broken. Notably, in SC-FM systems, a time reversal operation reverses both current and magnetization, leading to the conceptualization of superconducting magnetization diode effect (SMDE). In this variant, while the current direction remains fixed, the critical currents shall be different when reversing the magnetization. Here, the existence of SMDE in SC-FM heterostructures is demonstrated. SMDE uniquely maps magnetization states onto superconductivity by setting the read current between two critical currents for the positive and negative magnetization directions, respectively. Thus, the magnetization states can be read by measuring the superconductivity, while the writing process is accomplished by manipulating magnetization states through current-driven spin–orbit torque to switch the superconductivity. The proposed superconducting diode magnetoresistance in SC-FM heterostructures with an ideally infinite on/off ratio resolves the limitations of tunneling magnetoresistance in the magnetic tunneling junctions, thereby contributing to the advancement of superconducting spintronics.