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

Sch. of Electr. & Comput. Eng., Purdue Univ., West Lafayette, IN, USA
IEEE Transactions on Nanotechnology (Impact Factor: 1.83). 04/2011; 10(2):237 - 243. DOI: 10.1109/TNANO.2009.2037221
Source: IEEE Xplore


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(100) 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 Δ1-like and Δ5-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.

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