Theory of Solid State Physics group (S. Maekawa’s group), in collaboration with research groups from National Taiwan University and University of Tokyo has revealed that a giant spin Hall effect is caused by the skew scattering mechanism by iron magnetic impurities. Performing a first principle band structure calculation for iron impurities in Au, it is found that a novel type of Kondo effect due to strong correlation between electrons of iron orbitals induces a very large spin Hall angle, which explains recent observation of giant spin Hall effect using a device with iron-platinum (FePt) and gold (Au) electrodes [T. Seki et al., Nature Materials 7, 125 (2008)]. The result provides a new strategy for generating spin current which manipulates magnetic memories and quantum bits in spintronics devices. This research achievement was published in the Journal of the American Physical Society “Physical Review Letters” on 23, January 2009, and selected for a “Viewpoint in Physics” of the same issue.
Figure: Incident electron beam is converted to a transverse spin-polarized current (red arrow) by skew scattering due to the spin-orbit interaction of iron impurities.
Prof. Maekawa's group(Theory of Solid State Physics)