Dresden 2026 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 17: Quantum Dots and Wires: Rings, Wires and Transport

HL 17.4: Vortrag

Dienstag, 10. März 2026, 10:15–10:30, POT/0251

Effective Hamiltonians for Ge/Si core/shell nanowires from higher-order perturbation theory — Sebastian Miles¹, A. Mert Bozkurt¹, •Dániel Varjas^{2, 3, 4}, and Michael Wimmer¹ — ¹QuTech and Kavli Institute of Nanoscience, Delft University of Technology — ²IFW Dresden and Würzburg-Dresden Cluster of Excellence ct.qmat — ³Max Planck Institute for the Physics of Complex Systems — ⁴Budapest University of Technology and Economics

We theoretically explore the electronic structure of holes in cylindrical Germanium/Silicon core/shell nanowires using a perturbation theory approach. The approach yields a set of interpretable and transferable effective low-energy model parameters for the lowest few sub-bands up to fifth order in perturbation theory for various experimentally relevant growth directions. In particular, we are able to resolve higher-order cross terms, e.g., the dependency of the effective mass on the magnetic field. Our study reveals orbital inversions of the lowest sub-bands for low-symmetry growth directions, leading to significant changes of the lower order effective coefficients. We demonstrate a reduction of the direct Rashba spin-orbit interaction due to competing symmetry effects for low-symmetry growth directions. Finally, we find that the effective mass of the confined holes can diverge, yielding quasi flat bands interesting for correlated states. We show how one can tune the effective mass of a single spin band allowing one to tune the effective mass selectively to its divergent points.

Keywords: core/shell nanowire; effective Hamiltonian; g-factor; Rashba SOC; perturbation theory