Phase-Field Simulation of Superconductor-Ferromagnet Bilayer-Based Cryogenic Strain Sensor

Hybrid superconductor-ferromagnet materials have gained huge attention due to their opposite nature of electronic states, bringing up new properties and applications when coupled together. Cryogenic sensors and memories research significantly lag behind their conventional counterparts. Here, we investigated numerically the strain/motion sensing ability of superconductor-ferromagnet bilayer using Ginzburg–Landau equations for superconductivity and Landau-Lifshitz-Gilbert equations for ferromagnetism. Clear segregation of average carrier concentration of the superconductor layer, which defines its conductivity, was observed with various magnitudes of strain (i.e. 0%, 1%, and 5%). The current purge was used to bring the designed sensor to its ground state, whereas the sensor retained the information on the amount of strain for the extended period unless reset (by the current purge) for reuse. This work opens up a new direction for superconductor-ferromagnet bilayer device applications towards strain/motion sensors and/or transducers.