Evolution of magnetoconductance across the topological-to-trivial phase transition in thin films
Phys. Rev. B 114, 165108 – Published 8 September, 2026
DOI: https://doi.org/10.1103/j9kd-3n7s
Abstract
We investigate the evolution of electronic transport across the topological insulator to trivial band insulator quantum phase transition in thin films by tuning the indium concentration , which systematically reduces the effective spin-orbit coupling. The observed transport evolution is consistent with a topological-to-trivial phase transition near , while a crossover from diffusive transport to a strongly localized Anderson insulating regime occurs around . In the diffusive regime, the magnetoconductance is well described by the Hikami-Larkin-Nagaoka formalism, with the evolution of the weak antilocalization prefactor providing a transport signature consistent with the proposed topological-to-trivial phase transition. Beyond the diffusive limit, transport crosses into a variable range hopping regime, accompanied by a striking reversal of low-field magnetoconductance from negative to positive. The observed positive magnetoconductance, its pronounced anisotropy, and its temperature evolution point to an orbital origin of the response. These features are naturally captured by incorporating the incoherent hopping mechanism of Raikh et al. [Phys. Rev. B 45, 6015 (1992)] together with wave-function shrinkage, rather than through conventional quantum correction frameworks. Theoretical analysis based on first principles electronic structure calculations shows that increasing indium substitution suppresses the band inversion through the combined effects of indium-derived states and reduced spin-orbit coupling, supporting the interpretation of the observed transport evolution. Our results provide a unified picture of how topology, spin-orbit coupling, and disorder collectively describe the full field-temperature magnetotransport landscape in this material class.
