Spin transport and spin torque in half metallic ferromagnets at the nanoscale

The discovery of giant magnetoresistance in ferromagnetic metals has rekindled our interest in magnetism besides opening up a new field of science called ?spintronics?. Furthermore, the phenomenon of a spin-polarized current to induce magnetization reversal by spin-torque in similar ferromagnets defined a new field of nanomagnetism, actively pursued today. In spintronics, one exploits the spin of the electron in addition to its charge to realize novel devices and circuits essential for next-generation information and storage technology. In the above perspective, half-metallic ferromagnetic materials have not yet been explored in spite of their exceptional electron correlation effects. Such charge/spin/orbital correlations lead to an extremely rich phase diagram and complex physics. Being a half metal they also exhibit an almost complete or 100% spin polarization. In this proposal, I will use the large number of degrees of freedom derived from the above properties, to probe spin-transport and spin-torque induced non equilibrium magnetization-dynamics in La0.7Sr0.3MnO3, Fe3O4 etc. This will be done by tuning the compositional and structural parameters as well as epitaxial strain in these materials thereby tailoring their physical and functional properties. I will also study the spin dependent transport and scattering mechanisms of electrons in these tailored films and epitaxial heterostructures and determine their mean free path and lifetimes, a research direction not investigated so far. The utility of 100% spin polarization and the role of substrate induced magnetic anisotropy to spin torque induced magnetization reversal will be a novel way to enhance our understanding of the spin-torque phenomenon. This work will also contribute to our understanding of these intriguing materials and eventually lead to the design of novel materials with different functionalities besides bringing the prospect of all-oxide electronics closer to reality. Keywords: Spintronics, Ballistic Electron Magnetic Microscopy, Thin film technology, spin transport and spin-torque, half-metals, nanofabrication.