| AVS 60th International Symposium and Exhibition | |
| Magnetic Interfaces and Nanostructures | Monday Sessions |
| Session MI-MoM |
| Session: | Topological Materials, Rashba Systems, and Heusler Alloys |
| Presenter: | M. Donath, Muenster University, Germany |
| Authors: | M. Donath, Muenster University, Germany S.D. Stolwijk, Muenster University, Germany A.B. Schmdit, Muenster University, Germany K. Sakamoto, Chiba University, Japan P. Krueger, Muenster University, Germany |
| Correspondent: | Click to Email |
Tl/Si(111)-(1x1) is an outstanding example for a system with peculiar spin-orbit-induced spin effects in the surface electronic structure. An occupied surface state with classical in-plane Rashba-type spin topology around the center of the surface Brillouin zone was found to exhibit an out-of-plane spin rotation upon approaching the K point [1].
We used spin- and angle-resolved inverse photoemission with sensitivity to the in-plane and the out-of-plane spin-polarization directions to explore the unoccupied states. A recently developed rotatable source for spin-polarized electrons provided access to two spin-polarization directions. We identified an unoccupied surface state with the same spin topology as the occupied state, yet with a much larger spin-dependent splitting in energy of 0.6 eV. Theoretical calculations provide an explanation for this giant splitting. It is attributed to the strong localization of the unoccupied surface state close to the heavy Tl atom in contrast to the occupied state, which is located at the outermost Si atoms.
Since the lower-lying spin component approaches the Fermi level, this leads to almost completely out-of-plane polarized valleys in the vicinity of the Fermi level. As the valley polarization is oppositely oriented at the K and K’ points, backscattering should be strongly suppressed in this system.
[1] K. Sakamoto et al., Phys. Rev. Lett. 102, 096805 (2009).