Effects of geometry on spin-orbit Kramers states in semiconducting nanorings. (4th September 2019)

• Record Type: Journal Article
• Authors: Francica, G.; Gentile, P.; Cuoco, M.
• Is Part Of: Europhysics letters. Volume 127:Number 3(2019)
• Publication Date: 2019-09-04
• Subjects: 03.65.Vf -- 05.30.Rt -- 03.65.-w; Physics -- Periodicals; Electronic journals; 530.05
• DOI: 10.1209/0295-5075/127/30001
• Languages: English
• ISSNs: 0295-5075

Abstract

Abstract: The holonomic manipulation of spin-orbital degenerate states, encoded in the Kramers doublet of narrow semiconducting channels with spin-orbit interaction, is shown to be intimately intertwined with the geometrical shape of the nanostructures. The presence of doubly degenerate states is not sufficient to guarantee a non-trivial mixing by only changing the Rashba spin-orbit coupling. We demonstrate that in nanoscale quantum rings the combination of arbitrary inhomogeneous curvature and adiabatic variation of the spin-orbit amplitude, e.g., through electric-field gating, can be generally employed to get non-trivial combinations of the degenerate states. Shape symmetries of the nanostructure act to constrain the adiabatic quantum evolution. While for circular rings the geometric phase is not generated along a non-cyclic path in the parameters space, remarkably, for generic mirror-symmetric shape deformed rings the spin-orbit driving can lead to a series of dynamical quantum phase transitions. We explicitly show this occurrence and propose a route to detect such topological transitions by measuring a variation of the electron conductance into the semiconducting channel.