Magneto-transport behaviour of Bi2Se3-xTex: Role of disorder

TL;DR

This study investigates how disorder affects magnetotransport in Bi2Se3-xTex crystals, revealing changes in resistivity, oscillations, and weak antilocalisation phenomena across different Te doping levels.

Contribution

It provides a detailed analysis of disorder's role in magnetotransport properties of Bi2Se3-xTex, including carrier density, mobility, and WAL effects, which was not previously explored.

Findings

Te doping induces low-temperature resistivity upturns.

Suppression of Shubnikov de Hass oscillations with Te doping.

Observation of weak antilocalisation in Bi2SeTe2.

Abstract

Magnetoresistance and Hall resistance measurements have been carried out in fastcooled single crystals of Bi2Se3-xTex (x: 0 to 2) in 4 to 300 K temperature range, under magnetic fields up to 15 T. The variation of resistivity with temperature that points to a metallic behaviour in Bi2Se3, shows an upturn at low temperatures in the Te doped samples. Magnetoresistance measurements in Bi2Se3 show clear signatures of Shubnikov de Hass oscillations that gets suppressed in the Te doped samples. In the Bi2SeTe2 sample, the magneto-resistance shows a cusp like positive magneto-resistance at low magnetic fields and low temperatures, a feature associated with weak antilocalisation (WAL), that crosses over to negative magneto-resistance at higher fields. The qualitatively different magnetotransport behaviour seen in Bi2SeTe2 as compared to Bi2Se3 is rationalised in terms of the disorder, through an estimate of the carrier density, carrier mobility and an analysis in terms of the Ioffe Regel criterion with support from Hall Effect measurements.