Parasitic capacitance of FeCo/MgO/FeCo magnetic tunnel junctions

In this work, we report a theoretical investigation of parasitic capacitance in FeCo/MgO/FeCo magnetic tunnel junctions (MTJs). The electronic structures needed for accomplishment of this work are computed within the density functional theory using the full-potential linearized augmented plane-wave method (FLAPW) as implemented in Wien2k. Fixed-spin-moment (FSM) calculations are used to simulate the interfacial effects on the electronic structure of the electrodes. It is discussed that the charge screening at surfaces of the electrodes alters their local electric permittivities. The relative electric permittivities of the electrodes are calculated and their effects on the overall capacitance of the MTJ are estimated. Finally, capacitive properties of the MTJ are investigated and it is resulted that its capacitance, especially for the Co-ending electrodes, is not considerably dependent on an externally applied magnetic field.