Designing current-strain-assisted superconductor-ferromagnet multi-bit memories

Current superconducting memory devices lack the basic quality of high memory density for practical memories, mainly due to the size limitations of superconducting quantum interference devices. Here, we propose a superconductor-ferromagnet bilayer device with strain-pulse-assisted multi-bit ladder-type memory, by using strain-engineered ferromagnet domain structure to control carrier concentration in the superconductor, which is simulated by coupled Landau-Lifshitz-Gilbert and Ginzburg-Landau equations. Current- and strain-pulses are observed to deterministically control the resistivity of superconductor for one and two-bit device arrangements. The average carrier concentration of superconductor is observed to have multiple metastable states that can be controllably switched using current-pulse and strain-pulse to determine multiple resistivity states. These findings confirm the eligibility of superconductor-ferromagnet bilayers to be used as ladder-type multibit memories and open a new way for further theoretical and experimental investigations of the cryogenic memories.