The application of quantum technologies such as spintronics, solotronics, and quantum computing is highly promising when it comes to miniaturization in modern technology. In order to achieve effective devices, there is a need to investigate the spin properties of impurity interacting with the semiconductor lattice and confined carriers. Epitaxial quantum dots (QDs), representing zero-dimensional semiconductor structures, emerge as a model system offering a profound exploration of fundamental interactions in condensed matter. For instance, QDs serve as an invaluable tool for scrutinizing the spin characteristics of individual magnetic ions.
Vanadium is a transitional metal with a nuclear spin 7/2 and 3 electrons on the d shell. It exhibits spin 3/2 in V2+ configuration leading to two possible fundamental states with spin projection ±3/2 or ±1/2. Particular spin configuration is expected to depend on the strain of the crystal lattice in a QD.
In this study, we investigate self-assembled CdTe QDs doped with vanadium within a ZnTe barrier, created through molecular beam epitaxy. Our focus involves the observation of a single quantum dot containing a sole vanadium dopant, and the subsequent measurement of its magneto-optical properties. Through numerical modeling based on experimental data, we discern that the crucial phenomenon explaining the main features in the spectrum is the presence of sheer strain within the quantum dot. Ultimately, our findings lead us to the conclusion that vanadium in this context exhibits a spin of ±1/2, thereby rendering our system a realization of a qubit.
Authors: K. E. Połczyńska, T. Kazimierczuk, P. Kossacki and W. Pacuski
Physical Review B 111, 085428 (2025)
https://doi.org/10.1103/PhysRevB.111.085428
