Thin films of the topological insulator (BiSb)2Te3 oriented along the [0001] direction were grown via molecular beam epitaxy on substrates of Al2O3 (0001) and MgF2 (110) single crystals, as well as on an epitaxial thin film of the antiferromagnetic insulator MnF2 (110). Magnetoconductivity measurements of these samples showed close proximity of the Fermi level to the Dirac point and weak antilocalization at low temperature that was partially suppressed in the sample grown on the MnF2 layer. The magnetoconductivity data were fit to a model that describes the quantum corrections to the conductivity for the Dirac surface state of a 3-dimensional topological insulator, from which values of the Fermi velocity and the phase coherence length of the surface state charge carriers were derived. The magnetoconductivity of the (BiSb)2Te3 - MnF2 bilayer samples were fit to a model describing the crossover from weak antilocalization to weak localization due to magnetic doping. The results are consistent with the opening of an energy gap at the Dirac point in the (BiSb)2Te3 due to magnetic proximity interactions of the topological surface states with the antiferromagnetic MnF2 insulator.
@article{arxiv.2403.03116,
title = {Suppressed weak anti-localization in topological insulator - antiferromagnetic insulator (BiSb)$_2$Te$_3$ - MnF$_2$ thin film bilayers},
author = {Ryan Van Haren and David Lederman},
journal= {arXiv preprint arXiv:2403.03116},
year = {2024}
}