Disorder-driven localization and electron interactions in Bi$_x$TeI thin films

Abstract

Strong disorder has a crucial effect on the electronic structure in quantum materials by increasing localization, interactions, and modifying the density of states. Bi$_x$TeI films grown at room temperature and \SI{230}{K} exhibit dramatic magnetotransport effects due to disorder, localization and electron correlation effects, including a MIT at a composition that depends on growth temperature. The increased disorder caused by growth at 230K causes the conductivity to decrease by several orders of magnitude, for several compositions of Bi$_x$TeI. The transition from metal to insulator with decreasing composition $x$ is accompanied by a decrease in the dephasing length which leads to the disappearance of the weak-antilocalization effect. Electron-electron interactions cause low temperature conductivity corrections on the metallic side and Efros-Shklovskii (ES) variable range hopping on the insulating side, effects which are absent in single crystalline Bi$_x$TeI. The observation of a tunable metal-insulator transition and the associated strong localization and quantum effects in Bi$_x$TeI shows the possibility of tuning spin transport in quantum materials via disorder.