Probing the Spin Polarization of Sulfide-based Spintronic Materials @ University of Minnesota
January 11, 2010 :: Highlight from IRG3
: Mike Manno, Rachel Frakie, Chris Leighton- University of Minnesota
Highly spin-polarized magnets have the potential to radically improve the performance of many spintronic devices by increasing the spin polarization of the injected electrons. Recent work in Leighton's group in IRG3 by graduate student Mike Manno and undergraduate Rachel Frakie has addressed two of the biggest roadblocks to the development of such materials: Establishing reliable methods to accurately determine the polarization, and demonstrating the ability to maintain it in thin film structures. The unique Co1-xFexS2 system developed in the IRG was used as a model system for the application of a new method to determine bulk spin polarization. This approach was based on Compton scattering analyzed within the framework of first principles electronic structure calculations and was performed in collaboration with the University of Bristol, ISIS, and the University of Warwick in the UK, as well as the Spring-8 synchrotron source in Japan. The work provides a much-needed new method to probe the bulk spin polarization, sheds light on the controversial issue of the influence of the spin-dependence of the Fermi velocity, and provides crucial support for the sign reversal in the spin polarization of this material. In a related study the IRG built on their earlier development of reliable means for the deposition of high quality thin films of these sulfides to provide the first demonstration that the high spin polarization can be maintained in thin films. Exploiting an effect known as intergranular tunneling magnetoresistance (see figure), spin polarizations up to 90% were measured in (Co,Fe)S2 films. These are some of the highest values achieved in thin film materials and demonstrate great promise for future incorporation in heterostructures for fundamental spintronic studies.
Related publication(s):
- M. Manno, R. Frakie*, B. Bolon, C. Leighton, Appl. Phys. Lett. 95 182510 (2009)
- C. Utfeld, S.R. Giblin, J.W. Taylor, J.A. Duffy, C. Shenton-Taylor, J. Laverock, S.B. Dugdale, M. Manno, C. Leighton, M. Itou, Y. Sakurai, Phys. Rev. Lett. 103 226403 (2009)
