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O: Fachverband Oberflächenphysik

O 5: Spin-Orbit Interaction at Surfaces I

O 5.3: Vortrag

Montag, 14. März 2011, 11:45–12:00, WIL B321

Strong effect of substrate termination on Rashba spin-orbit splitting: Bi on BaTiO₃(001) from first principles — •Samir Abdelouahed and Jürgen Henk — Max Planck Institute of Microstructure Physics, Halle, Germany

A sizable Rashba splitting of surface states requires a number of ingredients: a strong atomic spin-orbit coupling, a steep surface-potential barrier, and a large in-plane potential gradient. We demonstrate by first-principles calculations that a suitable substrate termination is another prerequisite.

Our calculations for a Bi adlayer on BaTiO₃(001) show that the Rashba spin-orbit splitting in the Bi-6p states is strongly affected by the substrate termination. For the TiO₂ termination the absolute splitting is very large (about 0.23 Å⁻¹) and can be mildly affected by the orientation of the electric polarization in the ferroelectric substrate [1]. In striking contrast, the splitting becomes strongly reduced for the BaO termination (less than 0.07 Å⁻¹). Our findings are explained by the termination-dependent hybridization of the Bi surface states with electronic states in the substrate. It turns out that a strongly asymmetric charge density at the site of the heavy element (here: Bi) is a signature of a large Rashba splitting.

[1] H. Mirhosseini et al, Phys. Rev. B 81 (2010) 073406.