| AVS 63rd International Symposium & Exhibition | |
| Magnetic Interfaces and Nanostructures | Monday Sessions |
| Session MI+2D+AC-MoA |
| Session: | Magnetism and Spin Orbit Effects at Interfaces and Surfaces: Recent Experimental and Theoretical Advances |
| Presenter: | Markus Donath, Muenster University, Germany |
| Authors: | M. Donath, Muenster University, Germany K. Miyamoto, Muenster University, Germany H. Wortelen, Muenster University, Germany B. Engelkamp, Muenster University, Germany H. Mirhosseini, Max Planck Institute for Microstructure Physics, Germany T. Okuda, Hiroshima Synchrotron Radiation Center, Japan A. Kimura, Hiroshima University, Japan A.B. Schmidt, Muenster University, Germany J. Henk, Martin Luther University Halle-Wittenberg, Germany |
| Correspondent: | Click to Email |
Tungsten and tantalum are direct neighbors in the periodic table and exhibit, at first glance, a very similar electronic structure. Only the bands of tantalum are less occupied due to the lack of one electron. For W(110), an exceptional surface state was discovered [1]: Resembling a topological surface state (TSS), it exhibits a linear dispersion with a helical spin texture in reciprocal space, often called Dirac-cone-like behavior. Interestingly and again reminiscent of the TSS behavior, photoemission calculations predict a spin reversal upon changing the light polarization used for excitation from p to s [2]. We verified this orbital-symmetry-selective spin texture by spin-resolved photoemission [3]. This result unveils, in which way spin-orbit interaction entangles spin and orbital degrees of freedom. “Spin control” is not restricted to topological insulators but a much more general phenomenon.
A surface state, similar to the Dirac-cone-like state on W(110), may be expected for Ta(110), yet above the Fermi level. Surprisingly, our spin-resolved inverse-photoemission results do not show this state. Instead, spin-polarized unoccupied surface bands [4] and an occupied dz2surface state with Rashba-like spin texture [5] were identified, which have no equivalents on W(110). These findings are explained by subtle differences in the energetic positions of the surface states relative to the bulk states for W(110) and Ta(110), which critically depend on the values for the lattice constant and the surface relaxation.
[1] K. Miyamoto et al., Phys. Rev. Lett. 108, 066808 (2012); Phys. Rev. B 86, 161411(R) (2012); J. Electron Spectrosc. Relat. Phenom. 201, 53 (2015).
[2] H. Mirhosseini et al., New J. Phys. 15, 033019 (2013).
[3] K. Miyamoto et al., Phys. Rev. B 93, 161403(R) (2016).
[4] B. Engelkamp et al., Phys. Rev B 92, 085401 (2015).
[5] H. Wortelen et al., Phys. Rev. B 92, 161408(R) (2015).