Spin-resolved photoemission spectroscopy of the Heusler compound co2MnSi

Abstract

The Heusler compound Co2MnSi (CMS) is probably the most extensively studied half-metallic material. Its peculiar spin-dependent electronic properties have been addressed both theoretically and experimentally; they also already found wide application in prototypical spintronics devices. In this chapter we review our spinresolved photoemission studies conducted on the free surface of both stoichiometric and off-stoichiometric Co2MnαSi samples. Our findings shed light on the peculiar dependence observed in the performance of CMS-based magnetic tunnel junctions on theMn composition α.We also reviewour studies on the buried CMS/MgO interface, that could be directly investigated by spin-resolved low-energy photoemission spectroscopy. With this method we can then access the spin and symmetry properties of the interface electronic wave functions, which are ultimately responsible for the performance of CMS-based spintronic devices. In particular, the collected experimental data led us conclude that non-collinear spin moments at the CMS/MgO interface might be the main mechanism behind the controversially discussed temperaturedependent performance loss of state-of-the-art CMS-based magnetic tunnel junctions.