Prof. Dr. Rudolf Gross

Walther-Meißner-Institut Walther-Meißner-Str. 8 D-85748 Garching

Tel: +49 (0)89 - 289 - 14201 Fax: +49 (0)89 - 289 - 14206 Email: RUDOLF.GROSS@WMI.BADW.DE

Dr. Sebastian T.B. Gönnenwein

Walther-Meißner-Institut Walther-Meißner-Str. 8 D-85748 Garching

Tel: +49 (0)89 - 289 - 14226 Fax: +49 (0)89 - 289 - 14206 Email: GOENNENWEIN@WMI.BADW.DE

Dr. Matthias Opel

Walther-Meißner-Institut Walther-Meißner-Str. 8 D-85748 Garching

Tel: +49 (0)89 - 289 - 14237 Fax: +49 (0)89 - 289 - 14206 Email: OPEL@WMI.BADW.DE

Spin injection, spin transport and controllable ferromagnetism in transition metal doped ZnO

Semiconductors that are ferromagnetic above room temperature (RT) are in the focus of current research, as they combine ferromagnetic exchange with the versatile electronic properties of semiconductors. They are expected to lead to novel spintronic devices with improved electrical and optical properties. Promising material systems are so-called dilute magnetic semiconductors (DMS), in which itinerant charge carriers mediate a ferromagnetic coupling between the moments of dilute transition metal (TM) ions. Ferromagnetism has been observed in Mn doped GaAs or InAs, however, both with Curie temperatures well below RT. More promising in this respect is TM doped ZnO, for which RT ferromagnetism has been predicted in analogy to the III-V systems and until now observed in several experimental studies. The key objectives of this research proposal are (i) to clarify the physical foundations of ferromagnetism in ZnO:TM, (ii) to improve the process technology for the fabrication of highquality epitaxial thin films and heteroepitaxial multilayer structures as the basis of spintronic devices, (iii) the study of spin injection and spin transport in ZnO:TM based heterostructures, and (iv) the control of ferromagnetism in ZnO:TM by electric or strain fields. Regarding fabrication technology specific goals are the growth of epitaxial thin films of high crystalline quality and controlled doping by laser molecular beam epitaxy and the growth of heterostructures combining ZnO:TM with half-metallic oxides such as magnetite or suitable dielectrics for field effect devices. With respect to spin injection and spin transport specific objectives are the study of spin injection across ZnO:TM/ZnO or ZnO/magnetic oxide interfaces as well as the study of spin transport in vertical ZnO:TM/insulator/ZnO:TM structures.