Abstract
As the inversion symmetry is broken at a surface, spin-orbit interaction gives rise to spin-dependent energy shifts – a phenomenon which is known as the spin Rashba effect. Recently, it has been recognized that an orbital counterpart of the spin Rashba effect – the orbital Rashba effect – can be realized at surfaces even without spin-orbit coupling. Here, we propose a mechanism for the orbital Rashba effect based on sp orbital hybridization, which ultimately leads to the electric polarization of surface states. For the experimentally well-studied system of a BiAg2 monolayer, as a proof of principle, we show from first principles that this effect leads to chiral orbital textures in k-space. In predicting the magnitude of the orbital moment arising from the orbital Rashba effect, we demonstrate the crucial role played by the Berry phase theory for the magnitude and variation of the orbital textures. As a result, we predict a pronounced manifestation of various orbital effects at surfaces, and proclaim the orbital Rashba effect to be a key platform for surface orbitronics.
Highlights
The spin Rashba effect as a fundamental manifestation of spin-orbit coupling (SOC) at surfaces has revolutionized the spintronics research, and served as a foundation for a new field of spintronics rooted in relativistic effects – spin-orbitronics[1,2,3,4]
By referring to explicit first principles calculations, we demonstrate that including non-local effects[32,33,34,35,36,37,38] can drastically enhance the magnitude of the orbital Rashba effect (ORE)-driven orbital polarization of the surface states as compared to the k-dependent orbital moment (OM) obtained from simple atomic arguments
We have shown that sp orbital hybridization is the main mechanism for the ORE at surfaces of sp-alloys, which is manifest already without SOC
Summary
The spin Rashba effect as a fundamental manifestation of spin-orbit coupling (SOC) at surfaces has revolutionized the spintronics research, and served as a foundation for a new field of spintronics rooted in relativistic effects – spin-orbitronics[1,2,3,4]. As a consequence of the spin Rashba effect, the surface states created as a result of SOC and surface potential gradient exhibit finite spin polarization, which forms chiral textures in reciprocal k-space. This gives rise to a multitude of prominent phenomena such as Dzyaloshinskii-Moriya interaction[5,6,7,8,9], spin Hall effect[10], direct and inverse Edelstein effects[11,12], quantum anomalous Hall effect[13], and current-induced spin-orbit torques[14,15,16]. The tight-binding parameters were chosen so as to closely reproduce the first principles bandstructure
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
