Large magnetocapacitance of up to 456% at room temperature in FeCo/MgAl₂O₄/FeCo(001) magnetic tunnel junctions

Abstract Tunnel magnetocapacitance (TMC) ratios greater than 450% are observed at room temperature in epitaxial FeCo/MgAl 2 O 4 /FeCo(001) magnetic tunnel junctions (MTJs). A high TMC is observed at a low bias of 75 mV, which is suitable for low-power electronics. The fitting results between experimental data and calculation based on extended Debye–Fröhlich model reveal that the high TMC ratio is obtained owing to the high spin polarization of FeCo and the spin capacitance of the lattice-matched interface between FeCo and MgAl 2 O 4 . Based on this model, a TMC ratio could reach 1500% in MTJs with a spin polarization of 90%.