|
The Rashba effect [1] describes the momentum-dependent spin splitting of the
electron states at a surface or interface. It is the combined result of the relativistic
spin-orbit interaction (SOI) and the inversion-symmetry breaking. The control
of the Rashba effect by an applied electric field is at the heart of the proposed
Rashba-effect-based spintronics devices for manipulating the electron spinfor ma-
nipulating the electron spin in the semiconductors. The effect is expected to be
much stronger in the perovskite oxides owing to the presence of high-Z elements.
In this talk, I will introduce the Rashba effect and discuss how the Rashba SOI
at the surfaces and interfaces can be tuned by manipulating the two dimensional
electron gas (2DEG) by an applied electric field. The effect can be understood in
terms of a tight-binding model Hamiltonian for the d orbitals incorporating the
effect of electric field in terms of effective orbital overlap parameters [3]. From
first principles calculations we see that the Rashba SOI originates from the first
few layers near the surface and it therefore can be altered by drawing the 2DEG
to the surface or by pushing the 2DEG deeper into the bulk with an applied elec-
tric field. These ideas will be illustrated by a comprehensive density-functional
study of polar perovskite systems [4].
References
[1] E. I. Rashba, Sov. Phys. Solid State 2, 1109 (1960)
[2] A. Ohtomo and H. Hwang, Nature 427, 423 (2004); Z. Popovic, S. Satpathy,
and R. Martin, Phys. Rev. Letts. 101, 256801 (2008)
[3] K. V. Shanavas and S. Satpathy, Phys. Rev. Lett. 112, 086802 (2014);
K. V. Shanavas, Z. S. Popovic, and S. Satpathy, Phys. Rev. B 90, 165108
(2014)
[4] K. V. Shanavas, J. Electron Spectrosc., In press (2015)
|
