Magnetic exchange coupled nonreciprocal devices for cryogenic memory

TL;DR

This paper introduces a superconducting nonvolatile memory device using exchange-coupled superconductor and ferromagnetic insulators, demonstrating tunable superconductivity, heat-assisted writing, and nonreciprocal diode behavior at cryogenic temperatures.

Contribution

The work presents a novel device platform combining superconductors and ferromagnetic insulators for scalable, low-power, nonvolatile cryogenic memory with nonreciprocal properties.

Findings

Superconducting exchange coupling enables switching of superconductivity.

Memory exhibits heat-assisted magnetic writing capability.

Devices show high nonreciprocity with diode efficiencies over 60%.

Abstract

As computing power demands continue to grow, superconducting electronics present an opportunity to reduce power consumption by increasing the energy efficiency of digital logic and memory. A key milestone for scaling this technology is the development of efficient superconducting memories. Such devices should be nonvolatile, scalable to high integration density and memory capacity, enable fast and low-power reading and writing operations, and be compatible with the digital logic. We present a versatile device platform to develop such nonvolatile memory devices consisting of an exchange-coupled ultra-thin superconductor encapsulated between two ferromagnetic insulators (FIs). The superconducting exchange coupling, which is tuneable by the relative alignment between the FI magnetizations, enables the switching of superconductivity on and off. We exploit this mechanism to create a superconducting nonvolatile memory where single-cell writing is realized using heat-assisted magnetic recording, and explain how it can become a contender for state-of-the-art superconducting memories. Furthermore, below their critical temperatures, the memory elements show a marked nonreciprocity, with zero magnetic field superconducting diode efficiencies exceeding $\pm$60%, showing the versatility of the proposed devices for superconducting computing.