摘要:
This thesis presents a series of measurements investigating the spin physics of lateral quantum dots, defined electrostatically in the 2-D electron gas at the interface of a GaAs/AlGaAs heterostructure. The experiments span a range from open dots, where the leads of the dot carry at least one fully transmitting mode, to closed dots, where the leads are set to be tunnel barriers. For open dots, spin physics is inferred from measurements of conductance fluctuations; the effects of spin degeneracy in the orbital levels as well as a spin-orbit interaction are observed. In the closed dot measurements, ground state spin transitions as electrons are added to the dot may be determined from the motion of Coulomb blockade peaks in an in-plane magnetic field. In addition, this thesis demonstrates for the first time a direct measurement of the spin polarization of current emitted from a quantum dot, or a quantum point contact, during transport. These experiments make use of a spin-sensitive focusing geometry in which a quantum point contact serves as a spin analyzer for the mesoscopic device under test. Measurements are presented both in the open dot regime, where good agreement with theory is found, as well as the closed dot regime, where the data defies a simple theoretical explanation.