Abstract
Triplet-singlet spin relaxation in a vertical electrostatic quantum dot containing two interacting electrons is studied with a realistic model that includes the effects of finite thickness and screening. The spin relaxation mechanism is taken to be spin mixing via the part of the Dresselhaus Hamiltonian that is linear in the lateral momentum. The electron-electron interaction enhances relaxation and finite thickness suppresses it. The relaxation rate varies extremely rapidly with well width, $w$, approximately like $1∕{w}^{18}$ in zero magnetic field and $1∕{w}^{10}$ in a nonzero magnetic field. In addition, the rate oscillates with $w$ and this leads to further suppression of relaxation. If $w$ is sufficiently large the linear spin mixing mechanism is suppressed to the extent that it is no longer dominant.
Highlights
Spin relaxation in semiconductor quantum dots is currently under intense investigation because of its relevance to solid state quantum computing
The spin relaxation mechanism is taken to be spin mixing via the part of the Dresselhaus Hamiltonian that is linear in the lateral momentum
Pioneering experiments by Fujisawa et al.1 have shown that the triplet-singlet relaxation rate in elliptical dots is very low, and this has been confirmed for other dot types and transitions
Summary
Spin relaxation in semiconductor quantum dots is currently under intense investigation because of its relevance to solid state quantum computing. Theoretical work on spin flip processes was initiated by Khaetskii and Nazarov who studied excited state to ground state transitions in oneelectron circular and elliptical dots. They examined possible spin relaxation mechanisms and showed that linear spin mixing is the dominant one. Since excited to ground state transitions caused by spin mixing in various one-electron dot models have been studied theoretically as have transitions between Zeeman sublevels.. The aim of the present work is to investigate these effects in a vertical pillar dot, the same class of device as used in the experiments of Fujisawa et al.. The aim of the present work is to investigate these effects in a vertical pillar dot, the same class of device as used in the experiments of Fujisawa et al. As far as the authors are aware, there is only one other paper concerned with spin relaxation in a real device but this centers on a lateral dot which is very different from the vertical dot considered here
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
