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MA: Fachverband Magnetismus
MA 37: Spin Dependent Transport Phenomena
MA 37.2: Talk
Thursday, March 26, 2009, 15:30–15:45, HSZ 403
Ab initio study of antiferromagnetic Cr interlayers in Fe/MgO/Fe junctions — •Peter Bose1, Peter Zahn1, Ingrid Mertig1, and Jürgen Henk2 — 1Martin Luther University Halle-Wittenberg, Germany — 2Max Planck Institute of Microstructure Physics, Halle, Germany
One important issue for spintronics applications is the ability to tune the tunnel magnetoresistance (TMR) ratio, for example by insertion of metallic buffers into Fe/MgO/Fe tunnel junctions. Promising candidates are antiferromagnetic chromium interlayers which are intensively investigated experimentally and thus lend themselves support for a theoretical investigation.
We show by first-principles electronic-structure and transport calculations that the desired increase of the TMR ratio is not achieved. Instead, a strong exponential decay with Cr thickness is observed. Further, the conductances—and so the TMR ratio—oscillate with a period of 2 monolayers, which can be traced back to the layerwise antiferromagnetic structure of bcc Cr(001). A detailed analysis of layer-resolved and symmetry-decomposed spectral densities reveals that the electronic transport is mainly determined by the Cr/MgO interface.