We study analytically and numerically spin effects in monolayer armchair quantum wires and quantum dots. The interplay between intrinsic and Rashba spin orbit interactions induced by an electric field leads to helical modes, giving rise to spin filtering in time-reversal-invariant systems. The Rashba spin orbit interaction can also be generated by spatially varying magnetic fields. In this case, the system can be in a helical regime with nearly perfect spin polarization. If such a quantum wire is brought into proximity to an -wave superconductor, the system can be tuned into a topological phase, resulting in midgap Majorana fermions localized at the wire ends.
- Received 16 April 2013
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