Regensburg 2016 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 31: Silicon-based Semiconductors I

HL 31.2: Vortrag

Dienstag, 8. März 2016, 12:30–12:45, H14

A microscopic theory of valley dependent g-factors in Si/SiGe quantum dots — •Marko Rancic and Guido Burkard — University of Konstanz, 78464 Konstanz, Germany

In this theoretical study we model a Si/SiGe quantum dot with a micromagnet embedded on top. The micromagnet is present in order to achieve two-axis control of the electron spin states by oscillating it in real space (EDSR). The two-axis control of the electron spin is a necessary prerequisite for implementing a spin-based quantum bit. When both valley-orbit mixing and an in-plane magnetic field gradient are present the electronic g-factor can become valley dependent. The tilted Si/SiGe interface causes the valley and orbit degrees of freedom to mix, while the in-plane magnetic field gradient comes from the micromagnet. The formalism treats step-like interface defects as a continuous tilt of the Si/SiGe quantum well. Our findings suggest that the valley g-factor becomes valley dependent for a large parameter regime of the electrostatic confinement potential. Furthermore, by knowing the measured difference of valley dependent g-factors we are able to predict the valley splitting in a Si/SiGe quantum dot.