Strain-induced enhancement of the Seebeck effect in magnetic tunneling junctions via interface resonant tunneling: Ab-initio study

Abstract

We investigate the thermoelectric properties of Fe/MgO/Fe(001) magnetic tunnel junctions (MTJs) by means of the linear-response theory combined with a first-principles-based Landauer-Büttiker approach. We find that the Seebeck coefficient of Fe/MgO/Fe(001) MTJs strongly depends on the barrier thickness and the tetragonal distortion. A compressive tetragonal distortion of the in-plane lattice parameter in the MTJs provides interface resonant states just above the Fermi energy. This causes resonant tunneling in the MTJs and significantly enhances the Seebeck coefficient when the thickness of the MgO barrier is around 1 nm (four or five atomic layers of MgO). Moreover, an extensive tetragonal distortion of the in-plane lattice parameter pushes the interface states away from the Fermi energy, leading to a reduction of the Seebeck coefficient. Furthermore, we find that the interface resonant tunneling enhances the power factor of the MTJs for the compressive distortion. These results indicate that control of the barrier thickness and the tetragonal distortion will be effective for maximizing the thermoelectric properties of MTJs.

9 pages, 10 figures, published version

References in corpus (10)

• Spin Seebeck insulator
• Observation of the Spin-Seebeck Effect in a Ferromagnetic Semiconductor
• First-principles Green's-function method for surface calculations: a pseudopotential localized basis set approach
• Spin caloritronics in magnetic tunnel junctions: Ab initio studies
• Resonant electronic states and I-V curves of Fe/MgO/Fe(100) tunnel junctions
• Large magneto-Seebeck effect in magnetic tunnel junctions with half-metallic Heusler electrodes
• Conditions for requiring nonlinear thermoelectric transport theory in nanodevices
• Thermoelectric effects in FeCo|MgO|FeCo magnetic tunnel junctions
• Enhancement of thermovoltage and tunnel magneto-Seebeck effect in CoFeB based magnetic tunnel junctions by variation of the MgAl${}_2$O${}_4$ and MgO barrier thickness
• Large Tunneling Anisotropic Magneto-Seebeck Effect in a CoPt|MgO|Pt Tunnel Junction

Cited by in corpus (1)

• The optimum configuration design of a nanostructured thermoelectric device with resonance tunneling