Anisotropy of electron and holegtensors of quantum dots: An intuitive picture based on spin-correlated orbital currents

Abstract

Koenraad, P. M. (2016). Anisotropy of electron and hole g tensors of quantum dots: An intuitive picture based on spin-correlated orbital currents. Physical Review B, 93(3), [035311]. DOI: 10.1103/PhysRevB.93.035311 General rightsCopyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim. Using single spins in semiconductor quantum dots as qubits requires full control over the spin state. As the g tensor provides the coupling in a Hamiltonian between a spin and an external magnetic field, a deeper understanding of the g tensor underlies magnetic-field control of the spin. The g tensor is affected by the presence of spin-correlated orbital currents, of which the spatial structure has been recently clarified. Here we extend that framework to investigate the influence of the shape of quantum dots on the anisotropy of the electron g tensor. We find that the spin-correlated orbital currents form a simple current loop perpendicular to the magnetic moment's orientation. The current loop is therefore directly sensitive to the shape of the nanostructure: for cylindrical quantum dots, the electron g-tensor anisotropy is mainly governed by the aspect ratio of the dots. Through a systematic experimental study of the size dependence of the separate electron and hole g tensors of InAs/InP quantum dots, we have validated this picture. Moreover, we find that through size engineering it is possible to independently change the sign of the in-plane and growth direction electron g factors. The hole g tensor is found to be strongly anisotropic and very sensitive to the radius and elongation. The comparable importance of itinerant and localized currents to the hole g tensor complicates the analysis relative to the electron g tensor.

Electron and Hole g Tensors of Neutral and Charged Excitons in Single Quantum Dots by High-Resolution Photocurrent Spectroscopy

“…and P h,x−z = (g h,x − g h,z )/(g h,x + g h,z ) = (88.55 ± 0.02)%, as shown in Tables I. This can be ascribed to the anisotropic QD shape leading to the different spatial real-space wave function distributions and the non-zero orbital momenta carried by hole states [53][54][55].…”

Heavy-Hole States in Germanium Hut Wires

“…39 Improvements can be expected from an extended model that also involves the split-off band and the conduction band. 34,43,44 Finally, although our assumption of an infinite HW with a rectangular cross-section is a reasonable approximation for the elongated HW QDs realized here, the details of the confinement (and the strain) along all spatial directions can provide additional corrections. Taking all these elements fully into account is beyond the scope of the present work and requires extensive numerics.…”

Hyperfine coupling of hole and nuclear spins in symmetric (111)-grown GaAs quantum dots

“…The hole hyperfine constant in the (111) quantum dots is sensitive to the dot geometry through the light-heavy-hole mixing. This opens the way for engineering the hole-nuclear spin interaction [23,41]. The main route to control the effective heavy-hole hyperfine constant C eff in (111) quantum dots, given by Eq.…”