Linear-in-momentum spin orbit interactions in planar Ge/GeSi heterostructures and spin qubits
Résumé
We investigate the existence of linear-in-momentum spin-orbit interactions in the valence band of Ge/GeSi heterostructures using an atomistic tight-binding method. We show that symmetry breaking at the Ge/GeSi interfaces gives rise to a linear Dresselhaus-type interaction for heavy-holes. This interaction results from the heavy-hole/light-hole mixings induced by the interfaces and can be captured by a suitable correction to the minimal Luttinger-Kohn, four bands k.p Hamiltonian. It is dependent on the steepness of the Ge/GeSi interfaces, and is suppressed if interdiffusion is strong enough. Besides the Dresselhaus interaction, the Ge/GeSi interfaces also make a contribution to the in-plane gyromagnetic g-factors of the holes. The tight-binding calculations also highlight the existence of a small linear Rashba interaction resulting from the couplings between the heavy-hole/light-hole manifold and the conduction band enabled by the low structural symmetry of Ge/GeSi heterostructures. These interactions can be leveraged to drive the hole spin. The linear Dresselhaus interaction may, in particular, dominate the physics of the devices for out-of-plane magnetic fields. When the magnetic field lies in-plane, it is, however, usually far less efficient than the g-tensor modulation mechanisms arising from the motion of the dot in non-separable, inhomogeneous electric fields and strains.
Domaines
Physique [physics]Origine | Fichiers produits par l'(les) auteur(s) |
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