Electrical control of a confined electron spin in a silicene quantum dot

TL;DR

This paper investigates how to electrically control an electron spin in a silicene quantum dot, demonstrating rapid spin-flip times and the influence of edge effects and electric fields on spin dynamics.

Contribution

It introduces a method for fast electrical spin control in silicene quantum dots, highlighting the role of Rashba spin-orbit interaction and edge-induced intervalley coupling.

Findings

Rabi spin-flip times are around one nanosecond.

Tuning electric fields can reduce flip times to tens of picoseconds.

Edge effects induce intervalley coupling that speeds up spin transitions.

Abstract

We study spin control for an electron confined in a flake of silicene. We find that the lowest-energy conduction-band levels are split by the diagonal intrinsic spin-orbit coupling into Kramers doublets with a definite projection of the spin on the orbital magnetic moment. We study the spin control by AC electric fields using the non-diagonal Rashba component of the spin-orbit interactions with the time-dependent atomistic tight-binding approach. The Rashba interactions in AC electric fields produce Rabi spin-flips times of the order of a nanosecond. These times can be reduced to tens of picoseconds provided that the vertical electric field is tuned to an avoided crossing open by the Rashba spin-orbit interaction. We demonstrate that the speedup of the spin transitions is possible due to the intervalley coupling induced by the armchair edge of the flake. The study is confronted with the results for circular quantum dots decoupled from the edge with well defined angular momentum and valley index.