Spin-dependent scattering induced negative magnetoresistance in topological insulator Bi₂Te₃ nanowires.

ABSTRACT: Studies of negative magnetoresistance in novel materials have recently been in the forefront of spintronic research. Here, we report an experimental observation of the temperature dependent negative magnetoresistance in Bi₂Te₃ topological insulator (TI) nanowires at ultralow temperatures (20?mK). We find a crossover from negative to positive magnetoresistance while increasing temperature under longitudinal magnetic field. We observe a large negative magnetoresistance which reaches -22% at 8?T. The interplay between negative and positive magnetoresistance can be understood in terms of the competition between dephasing and spin-orbit scattering time scales. Based on the first-principles calculations within a density functional theory framework, we demonstrate that disorder (substitutional) by Ga⁺ ion milling process, which is used to fabricate nanowires, induces local magnetic moments in Bi₂Te₃ crystal that can lead to spin-dependent scattering of surface and bulk electrons. These experimental findings show a significant advance in the nanoscale spintronics applications based on longitudinal magnetoresistance in TIs. Our experimental results of large negative longitudinal magnetoresistance in 3D TIs further indicate that axial anomaly is a universal phenomenon in generic 3D metals.

SUBMITTER: Bhattacharyya B 

PROVIDER: S-EPMC6534536 | biostudies-literature | 2019 May

REPOSITORIES: biostudies-literature