An NSF Materials Research Science and Engineering Center (MRSEC)

1. Center for Emergent Materials The Ohio State University http://cem.osu.edu New materials for the spintronic toolbox Highly ordered Sr2CrReO6 films shed light on the role of spin-orbit coupling The field of “spintronics” has the potential to deliver electronic devices that are both faster and consume less power than the current devices. To realize this potential materials where the spins of the mobile electrons are spin polarized are needed. The double perovskite Sr2CrReO6 is one such promising material. Theoretical studies predict that at room temperature it should be a metal where 85−100% of the mobile electrons have parallel spins. However, experimental studies of Sr2CrReO6 have been hampered by the inability of researchers to keep Cr and Re atoms from occasionally switching places in the crystal. These “mistakes” called antisite defects negatively impact the magnetic and electrical properties. Researchers at The Ohio State University have for the first time succeeded in preparing high quality epitaxial films of Sr2CrReO6 where the Cr and Re atoms are nearly perfectly ordered. Measurements made on these films shed new light on the properties of this material. The effect of spin-orbit coupling, a property associated with compounds containing heavy elements (in this case Re), is evident in the magnetic properties. More surprising is the observation that the material is a semiconductor rather than a metal, something that had not been anticipated. Not only is the ability to grow highly ordered double perovskite films a technological breakthrough, the unexpected semiconducting behavior is likely to stimulate new studies to understand the intriguing properties of Sr2CrReO6. (a) STEM images of a Sr2CrReO6 (001) film viewed along <110> direction, showing the high degree of Cr/Re ordering. (b) A low-magnification TEM image of a Sr2CrReO6 film showing no visible dislocation defects. Co Au Co Fengyuan Yang, Adam Hauser, Hamish Fraser, Robert Williams, Manisha Genc, Jennifer Soliz, & Patrick Woodward An NSF Materials Research Science and Engineering Center (MRSEC) Supported under Award Number DMR-0820414