Magnetoresistance of magnetic tunnel junctions with low barrier heights

The magnetoresistance of low-barrier magnetic tunnel junctions (MTJs) was studied within a two-band model of free electrons in ferromagnetic electrodes, taking into consideration image forces. For MTJs with an MgO insulator, explanations are given of the giant tunneling magnetoresistance (TMR) effect and the effect of increasing TMR as the width of the MgO barrier increases. It is shown that TMR and the electron current density through MTJs depend strongly on the dielectric constant of the MgO insulator. It is found that the TMR of low-barrier MTJs reaches a maximum at a particular value of the applied bias voltage. It is demonstrated that the electron current density through low-barrier MTJs can be high enough to switch the magnetization of a ferromagnetic electrode.