Independent-Band Tight-Binding Parameters for Fe–MgO–Fe Magnetic Heterostructures

We present a computationally efficient and transferable independent-band tight-binding model (IBTB) for spin-polarized transport in heterostructures with an effort to capture the band structure effects. As an example, we apply it to study the transport through Fe–MgO–Fe(1 0 0) magnetic tunnel junction devices. We propose a novel approach to extract suitable tight-binding parameters for a material by using the energy resolved transmission as the benchmark, which inherently has the band structure effects over the 2-D transverse Brillouin zone. The IBTB parameters for various symmetry bands for bcc Fe(1 0 0) are first proposed which are complemented with the transferable tight-binding parameters for the MgO tunnel barrier for the $\Delta_1$-like and $\Delta_5$-like bands. The nonequilibrium Green’s function formalism is then used to calculate the transport features like J–V characteristics, voltage dependence, and the barrier width dependence of the tunnel magnetoresistance ratio are captured quantitatively, and the trends match well with the ones observed in ab initio methods.