Dr. Jacob J Krich
Physics Department
Harvard University


"Cubic Dresselhaus Spin-Orbit Coupling in GaAs Quantum Dots"

The bulk Dresselhaus spin-orbit coupling in GaAs breaks into two terms when electrons are confined in a quasi-2D system on a (001) plane; one term is linear in the electron momentum and the other is cubic. The cubic Dresselhaus term is generally smaller than the linear term, but in confined systems, such as quantum dots, its effects can be important. Using a semiclassical billiard model, we estimate the magnitude of the cubic Dresselhaus induced avoided crossings in a closed quantum dot in a Zeeman field. Using these results, together with previous analyses based on Random Matrix Theory, we calculate corresponding effects on the conductance through an open quantum dot. Combining our results with an experiment on conductance through an 8 um^2 quantum dot suggests that 1) the GaAs Dresselhaus coupling constant is about one third of the most commonly cited value and 2) the majority of the spin-flip component of spin-orbit coupling can come from the cubic Dresselhaus term.