First principle study on TMR effect in A-MgO-A (A = Fe, Co and Ni) magnetic tunnel junction

Abstract

• The role of electrode materials in TMR devices have investigated using DFT with Non-Equilibrium Green's Function (NEGF). • TMR effect is existing in Co-MgO-Co, Fe-MgO-Fe and Ni-MgO-Ni systems. • Iron electrodes have very high TMR efficiency than nickel and cobalt electrode. Abstract Magnetic tunnel junctions are used in storage devices. Electron transport in magnetic tunnel junctions highly dependents upon spin states of electron in ferromagnetic material. Iron, cobalt and nickel are room temperature ferromagnetic materials, magnetic tunnel junctions have been constructed using these materials as electrode and MgO as insulating layer (Co-MgO-Co, Fe-MgO-Fe and Ni-MgO-Ni). Total density of states, projected density of states and transmission coefficient have been calculated using non-equilibrium Green’s function (NEGF) with density functional theory (DFT) to analyze the spin transport properties of these devices. To study the TMR efficiency of these devices, TMR percentage at zero bias conductance was calculated based on optimistic and pessimistic. Our result shows that, iron ferromagnetic electrodes have very high TMR efficiency than nickel and cobalt electrode.