Study of Spin-Orbit Interaction with Magnetic Focusing

Abstract

Spin an intrinsic quantum number of particles attracts lots of interest from scientists as it is a remarkable property that cannot be understood in classical physics Although the spin has been investigated extensively there remains a challenge to utilize spin for electronic application: one has to apply and vary a large magnetic field to create the energy difference between opposite spins which is extremely impractical Amazingly in mesoscopic systems with strong spin-orbit interaction particles’ spin are coupled to their momentum resulting in the appearance of an effective magnetic field when the particles are travelling perpendicular to an electric field Thus the spins could be manipulated in an electrical manner which is much more convenient than the magnetic counterpart In this thesis we demonstrate the spin selectivity of the quantum point contacts and develop a new technique to detect the strength of spin-orbit interaction which may hold the key to realize spin-based applications by electrical means In our experiment the two spin currents with different spin orientation are spatially separated by a weak transverse magnetic field due to the Rashba spin-orbit coupling This spatially separation of the spin currents allows us to investigate the spin selectivity of the quantum point contact Because the device geometry is smaller than the mean free path for momentum relaxation the time evolution of the quantum states are coherent and the spin precession is observed the strength of the spin-orbit interaction as a function of top-gate voltage is therefore extracted

Date of Award	2014 Sept 3
Original language	English
Supervisor	Tse-Ming Chen (Supervisor)