Volume 127, Number 3, August 2019
|Number of page(s)||6|
|Published online||04 September 2019|
Effects of geometry on spin-orbit Kramers states in semiconducting nanorings
1 CNR-SPINM - I-84084 Fisciano (Salerno), Italy
2 Dipartimento di Fisica “E. R. Caianiello”, Università di Salerno - I-84084 Fisciano (Salerno), Italy
Received: 8 February 2019
Accepted: 17 July 2019
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.
PACS: 03.65.Vf – Phases: geometric; dynamic or topological / 05.30.Rt – Quantum phase transitions / 03.65.-w – Quantum mechanics
© EPLA, 2019
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