100% spin polarized Heusler compounds highly promising for spin-electronics

1. Exceptional-quality Heusler films for spin-electronics Fengyuan Yang, Ohio State University, DMR1107637 • X2YZ (e.g. Co2FeSi) Heusler crystal Heusler compounds are a large family of complex materials with many interesting properties. This DMR project focuses on magnetic Heuslers with 100% spin polarization and very high Curie temperatures (over 800C) which are highly desired for spin-electronic applications. Despite demonstration of high-performance prototype Heusler spin-electronic devices, the fabrication of high-quality Heusler films remains a major challenge, which hinders the understanding of their intrinsic magnetic and electronic properties. Using a innovative sputtering technique, we demonstrated the growth of Co2FeAl0.5Si0.5 films with crystalline quality comparable to those of the best semiconductor films. The Co2FeAl0.5Si0.5 films show clear magnetocrystalline anisotropy and outstanding microwave behavior with low magnetic damping. The availability of Heusler films with exceptional quality will lead to the understanding of the underlying mechanisms in Heusler compounds and facilitate their applications in next-generation technologies. • 100% spin polarized Heusler compounds highly promising for spin-electronics • Fully-ordered L21 structure needed for 100% spin polarization • Large family (hundreds) of Heusler compounds with a variety of intriguing properties • X-ray diffraction of a Co2FeAl0.5Si0.5 (CFAS) film • Made by a novel sputtering technique • Clear Laue oscillations indicate highly uniform smooth films typically seen in high-quality semiconductor films, but not in Heusler films • X-ray rocking curve of the Co2FeAl0.5Si0.5 film • Rocking curve with a peak width of 0.0051 demonstrates the highest crystalline quality of Hesuler films made to date • The exceptionally sharp rocking curve rivals those of the best semiconductor films

2. Exceptional-quality Heusler films for spin-electronics Fengyuan Yang, Ohio State University, DMR1107637 This Materials World Network (MWN) grant supports international collaboration between two teams at the Ohio State University and Institute for Solid State Research (IFW) in Dresden, Germany with common scientific interests and complementary expertise. In Summer, 2012, a female graduate student from Ohio State visited Dresden for 3 weeks for the growth of double perovskite single crystals. The PIs of the two sides also visited each other’s institution in the past year. In addition, an undergraduate student worked in the PI’s group in summer, 2012 on Heusler epitaxial films and produced excellent results that will lead to publications soon. Double perovskite Single crystals Heusler epitaxial films Dresden, Germany International collaboration between the Ohio State University and IFW in Dresden, Germany