Regensburg 2019 – scientific programme

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MA: Fachverband Magnetismus

MA 4: Topological insulators and spin-dependent transport phenomena

MA 4.11: Talk

Monday, April 1, 2019, 12:15–12:30, H52

Nonmagnet-Barrier Interface Drives Tunnelling Anisotropic Magnetoresistance — •Philipp Risius, Carsten Mahr, Michael Czerner, and Christian Heiliger — Institut für theoretische Physik, Justus-Liebig-Universität Gießen, Gießen

Tunnel junctions with a single ferromagnetic layer (semi-magnetic tunnel junction, SMTJ) may show magnetoresistance if spin-orbit interaction (SOI) is present in the ferromagnetic layer. This effect is called tunneling anisotropic magnetoresistance (TAMR). SMTJs employing a thin iron layer, magnesium oxide as tunnel barrier, and vanadium as leads (V|Fe|MgO|V) show TAMR and an appreciable spin-orbit torque at room temperature [1]. We investigate the origins of TAMR by calculating the transport across SMTJs from first principles, and investigate the effect of disorder at the Fe|V interface. For this, we utilized a fully relativistic Korringa-Kohn-Rostoker non-equilibrium Green’s function method including the coherent potential approximation and vertex corrections [2]. We recovered the k-resolved transmission and temperature-dependent TAMR ratio. Crucially, we show that the effect depends on a subtle interplay of the interfaces on both sides of the tunnel barrier, and that the magnitude of SOI at the ferromagnet-insulator interface can even be secondary to the choice of materials.
 [1] S. Miwa, J. Fujimoto, P. Risius et al., Phys. Rev. X 7(3), 031018 (2017).
 [2] C. Franz, M. Czerner and C. Heiliger, J. Phys. Condens. Matter 25, 425301 (2013).