Quantum coherence phenomenon in disordered Bi2SeTe2 topological single crystal: effect of annealing. (24th March 2017)

• Record Type: Journal Article
• Authors: Amaladass, E P; Devidas, T R; Sharma, Shilpam; Mani, Awadhesh
• Is Part Of: Journal of physics. Volume 29:Number 17(2017)
• Publication Date: 2017-03-24
• Subjects: topological insulators -- weak antilocalization -- weak localization -- linear magnetoresistance -- mobility -- electronic disorder; Condensed matter -- Periodicals; Matière condensée -- Périodiques; Vaste stoffen; Vloeistoffen; Natuurkunde; Electronic journals; Computer network resources; 530.4105
• DOI: 10.1088/1361-648X/aa62e0
• Languages: English
• ISSNs: 0953-8984

Abstract

Abstract: We report a comparative magnetotransport study on pristine and annealed Bi2 SeTe2 single crystals. The pristine sample shows a metallic trend from 300 to 180 K, and an insulating behavior for T < 180 K, whereas the annealed sample exhibits an insulating nature in the entire 4.2–300 K temperature range. Magnetoresistance (MR) of pristine and annealed samples reveals contrasting behaviour as a function of temperature ( T ) and magnetic field ( B ). At 4.2 K, the pristine sample shows weak antilocalization (WAL) behavior at low fields and transforms to weak localization (WL) behavior (negative MR) for B > 2.5 T. Further, the quantum MR behaviours seen at low temperature gradually transform to classical B 2 dependent upon increasing the temperatures. In contrast, the annealed sample shows a WAL at small field superimposed on a parabolic feature for B > ±4 T at low temperatures ( T < 20 K). It shows a linear MR at intermediate temperatures (40 K < T < 100 K) and a parabolic MR at temperatures T > 100 K. Hall measurements on both samples exhibit a nonlinear behavior at 4.2 K pointing to the existence of two types of carriers with different mobility. The annealed sample also shows a drastic decrease in mobility by one order of magnitude and a reduction in Ioffe–Regel parameter ( k F l ) by a factor of ~3. Disorder-induced localization of bulk carriers and its coexistence with localization-immune surface carriers at low T leads to WAL and WL. MR observed in the annealed sample can be attributed to the presence of both quantum–classical contribution and has been analysed using the Hikami–Larkin–Nagaoka (HLN) equation.