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O: Fachverband Oberflächenphysik

O 41: Frontiers of Electronic Structure Theory: Focus on Topology and Transport I

O 41.3: Vortrag

Dienstag, 8. März 2016, 14:45–15:00, H24

The orbital Rashba effect — •Dongwook Go^1,2, Patrick Buhl¹, Gustav Bihlmayer¹, Yuriy Mokrousov¹, Hyun-Woo Lee², and Stefan Blügel¹ — ¹Institute for Advanced Simulation and Peter Grünberg Institut, Forschungszentrum Jülich and JARA, D-52425 Jülich, Germany — ²Department of Physics, Pohang University of Science and Technology, 37673 Pohang, Korea

We present a new surface phenomenon called the orbital Rashba effect, analogous to the spin Rashba effect. The effect is described by the orbital Rashba Hamiltonian, H_orb−R(k)=α_orb−RL· (ẑ×k), where L is the orbital moment derived from atomic orbitals and α_orb−R is the orbital Rashba constant. This leads to orbital-dependent energy splittings and orbital texture in the k-space. The mechanism behind the emergence of the H_orb−R(k) can be understood as the k-dependent magnetoelectric coupling due to atomic orbital hybridization. In the presence of intra-atomic spin-orbit coupling, the spin moment is aligned parallel or antiparallel to the orbital moment, thus the spin Rashba effect is recovered. As an example, we present a tight-binding and an ab initio study of the Bi/Ag(111) surface alloy, where the hybridization between a Ag s-orbital and a Bi p-orbital leads to the orbital Rasbha effect that is dominant over the spin one. The orbital Rashba effect is a key to new physics and to understanding spin-orbit driven physics at surfaces and interfaces, such as Dzyaloshinskii-Moriya interaction, non-collinear magnetism, etc.