Magnetoconductance crossover and non-linear Hall effect in MBE-grown Cr-doped Bi$_{2}$Te$_{2}$Se

ORAL

Abstract

Recent predictions have shown that the magnetoconductance (MC) of a topological insulator should show a crossover from negative MC to positive MC when time-reversal symmetry is broken [1]. Observations of this crossover have been reported in 3 QL thick Cr-Bi$_{2}$Se$_{3 }$[2] in the quasi-2D regime where surface hybridization is not negligible. We report magneto-transport results on 15 QL thick Cr-doped and undoped Bi$_{2}$Te$_{2}$Se films grown on Si (111) substrates by MBE. The undoped film exhibits weak anti-localization at low temperatures. In the Cr-doped film, a crossover from negative to positive MC is observed versus temperature at T=12 K. SQUID measurements show that the sample is ferromagnetic in this temperature range. In addition, a non-linear Hall voltage is observed despite the large bulk carrier concentration. This paves the way for further experiments on (Bi,Cr)$_{2}$Te$_{2}$Se in our search for the quantum anomalous Hall effect. [1] H.Z. Lu et al. Phys. Rev. Lett. \textbf{107}, 076801(2011). [2] M.Liu et al. arXiv 1103.3353(2011).

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Authors

  • Badih Assaf

    Physics Dept. Northeastern University, Physics Department, Northeastern University, Boston, MA

  • Peng Wei

    MIT, Francis Bitter Magnet Lab, Francis Bitter Magnet Lab, MIT, Cambridge, MA, FBML, MIT, Cambridge, USA, FBML, MIT

  • F. Katmis

    MIT, Francis Bitter Magnet Lab, Francis Bitter Magnet Lab, MIT, Cambridge, MA, MIT, Department of Physics, MIT, Cambridge, USA

  • Jagadeesh S. Moodera

    Massachusetts Institute of Technology, MIT, Francis Bitter Magnet Lab, Francis Bitter Magnet Lab and Physics Department, MIT, Cambridge, MA, MIT, Department of Physics, MIT, Cambridge, USA, Francis Bitter Magnet Lab., FBML and Physics Dept., MIT

  • Don Heiman

    Northeastern University, Physics Department, Northeastern University, Physics Dept. Northeastern University, Physics Department, Northeastern University, Boston, MA