Weak antilocalization and electron-electron interactions in topological insulator BixTey films deposited by sputtering on Si(100)

Abstract

Topological insulators (TIs) which exhibit spin-momentum locking constitute an interesting class of quantum materials. In this paper, we present a systematic method to prepare ${\mathrm{Bi}}_{x}{\mathrm{Te}}_{y}$ films having tunable Bi/Te composition by employing a direct current (DC) cosputtering technique. Films of three different Te compositions, namely, the Te-deficient (BiTe), Te-stoichiometric (${\mathrm{Bi}}_{2}{\mathrm{Te}}_{3}$), and Te-excessive (${\mathrm{BiTe}}_{3}$) phases, have been investigated in detail by performing the measurements of their temperature-dependent resistivity and in-plane and out-of-plane magnetoresistance responses. Clear evidence of the presence of a weak antilocalization effect and electron-electron interaction are observed in all three films having different phases of Bi-Te system. Using the Hikami-Larkin-Nagaoka and Al'tshuler-Aronov models, the topological characteristics have been evidently distinguished in these three different phases of ${\mathrm{Bi}}_{x}{\mathrm{Te}}_{y}$. The analysis of the fitting of the experimental magnetotransport data is performed to quantitatively determine the critical model parameters, viz., phase coherence length (${l}_{\ensuremath{\phi}}$), surface state penetration depth ($\ensuremath{\lambda}$), coherency factor ($\ensuremath{\alpha}$), and dephasing parameter ($p$) through which Berry phase and dimensionality of transport channels can be estimated. In this paper, we reveal a systematic correlation between the composition of the ${\mathrm{Bi}}_{x}{\mathrm{Te}}_{y}$ films and their topological properties. The parameter $\ensuremath{\kappa}$, slope of temperature dependence of conductivity correction, is studied at different magnetic fields, which suggested that the Te-stoichiometric sample shows better features of topological properties than the Te-deficient and Te-excessive samples. These experimental observations are supplemented by first-principles calculations. Additionally, we demonstrate that TIs can be grown by the sputtering technique as is desired for realizing industrial applications.