Ground State Spin and Coulomb Blockade Peak Motion in Chaotic Quantum Dots
Harvard University Cambridge United States
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We investigate experimentally and theoretically the behavior of Coulomb blockade CB peaks in a magnetic field that couples principally to the ground-state spin rather than the orbital moment of a chaotic quantum dot. In the first part, we discuss numerically observed features in the magnetic field dependence of CB peak and spacings that unambiguously identify changes in spin S of each ground state for successive numbers of electrons on the dot, N. We next evaluate the probability that the ground state of the dot has a particular spin S, as a function of the exchange strength, J, and external magnetic field, B. In the second part, we describe recent experiments on gate-defined GaAs quantum dots in which Coulomb peak motion and spacing are measured as a function of in-plane magnetic field, allowing changes in spin between N and N 1 electron ground states to be inferred.