This award supports an international collaborative research team from the Ohio State University and the Leibniz Institute (IFW) in Dresden, Germany to realize and understand half-metallicity (i.e. 100% spin polarization of conduction electrons) in Heusler compounds and double perovskites. These two families of complex materials contain the vast majority of half-metallic compounds with high Curie temperatures that hold the promise of highly spin polarized transport at room temperature. To advance both our fundamental understanding as well as the technological promise of spin-polarized transport in these two families, this partnership brings together complementary expertise in high-quality epitaxial film deposition of complex materials and spin polarization measurements at the Ohio State University and single-crystal growth of these materials using the state-of-the-art facilities at the Leibniz Institute in Germany. Despite their promise, their chemical complexity and sensitivity to defects and antisite disorder has limited studies of Heusler compounds and double perovskites in prototype and real devices. Progress is also hindered by the fact that many aspects of the fundamental physics are still not well understood. This project has two aims: (1) deposit high quality, half-metallic epitaxial films and magnetic tunnel junctions of Heusler compounds with high Curie temperatures using off-axis ultrahigh vacuum sputtering, coupled with characterization of their structural, chemical, magnetic, electronic, spin polarization, and element-specific magnetic moments; (2) grow single crystals of half-metallic double perovskites. Availability of such crystals will enable investigations of their intrinsic spin polarization and magnetotransport properties. The true promise of these materials can only be assessed by separating intrinsic properties from extrinsic contributions originating from structural and chemical inhomogeneity. The goal of this project is to establish the scientific and technical foundations needed to incorporate half metallic materials in spintronic devices.
This international collaboration combines the collective and complementary expertise needed to realize the promise of half-metallic ferromagnets for use in spintronics. The availability of highly spin-polarized ferromagnets for room temperature applications will establish a groundwork that has the potential to revolutionize computing. In addition, this effort will strengthen the ties between US and German communities that will enhance the research infrastructure of both partner institutions. Finally, the scientific challenges, as well as the interdisciplinary and international nature of the research program will provide excellent training for the student researchers and junior scientists.