Manipulation of magnetically ordered states by electrical means is among the most promising approaches towards novel spintronic applications. Modern devices of the information age are expected to be highly integrated and ultra fast which in turn demands for lowest power consumption to avoid overheating. Electric control of magnetism provides an almost powerless approach to manipulate magnetic states for data storage and processing purposes. Electric control of exchange bias, a specific control of the magnetic hysteresis of a ferromagnetic thin film, will play an important role in a large class of future spintronic devices. We work on its realization with the help of the magnetoelectric antiferromagnet Cr2O3. The latter replaces today's passive pinning layers in exchange bias heterostructures by an active magnetoelectric material. Recently, a very unusual specific surface magnetic order which enables magnetoelectric control of a net magnetic moment of the Cr2O3 (111) surface has been predicted by our first principle calculations and experimental evidence has been found by magnetometry and spin polarized photoemission. The very unusual robustness of this highly spinpolarized surface state which exists close to room temperature together with the ability to control it by electrical means makes this finding very attractive for further investigations and the implementation of Cr2O3 as unique material in prototypical spintronic devices.
This research is supported by the National Science Foundation, Division of Materials Research, Materials Research Science and Engineering Program, Grant 0820521.
A net surface magnetization evolving in the antiferromagnetic single domain state of Cr2O3 (111).