Spin Focusing System with Controllable Rashba Spin-Orbit Interaction

Abstract

In the past time spins were like ghosts which everybody talked about and few had seen Although recently spin dynamics has been studied extensively there are still some unknowns about the mechanism of spin Based on the model of spinorbit interaction and previous experiment[1] it has been suggested that different spin states of electrons separately own different momenta Therefore we would like to know how the momentum of electrons with different spin states will vary as a function of Rashba spin-orbit interaction In our experiment we design a quantum device consisting of two quantum point contacts which are patterned in focusing geometry By applying a weak transverse magnetic field two spin states of electrons injected from one quantum point contact have different momenta and travel in different cyclotron orbits Through measuring focusing peak[2] we are allowed to directly investigate the spin-orbit coupling and its influence on the spindependent cyclotron motion In order to see how Rashba spin-orbit interaction will affect the momentum of electrons with different spin states we also add a top gate on the area of cyclotron motion to change the strength of Rashba spin-orbit interaction Our experimental results not only further suggest that we could use this simple method to directly measure the strength of spin-orbit interaction in the material but also provide an application for development of quantum computers by an electrical control of spin-orbit interaction which reveals evidence on how momentum are affected by spin-orbit interaction

Date of Award	2014 Aug 6
Original language	English
Supervisor	Tse-Ming Chen (Supervisor)