Shubnikov-de Haas Oscillations of High-Mobility Holes in Monolayer and Bilayer WSe_{2}: Landau Level Degeneracy, Effective Mass, and Negative Compressibility

Babak Fallahazad; Hema C P Movva; Kyounghwan Kim; Stefano Larentis; Takashi Taniguchi; Kenji Watanabe; Sanjay K Banerjee; Emanuel Tutuc

doi:10.1103/PhysRevLett.116.086601

Shubnikov-de Haas Oscillations of High-Mobility Holes in Monolayer and Bilayer WSe_{2}: Landau Level Degeneracy, Effective Mass, and Negative Compressibility

Phys Rev Lett. 2016 Feb 26;116(8):086601. doi: 10.1103/PhysRevLett.116.086601. Epub 2016 Feb 23.

Authors

Babak Fallahazad¹, Hema C P Movva¹, Kyounghwan Kim¹, Stefano Larentis¹, Takashi Taniguchi², Kenji Watanabe², Sanjay K Banerjee¹, Emanuel Tutuc¹

Affiliations

¹ Department of Electrical and Computer Engineering, Microelectronics Research Center, The University of Texas at Austin, Austin, Texas 78758, USA.
² National Institute of Materials Science, 1-1 Namiki Tsukuba, Ibaraki 305-0044, Japan.

PMID: 26967432
DOI: 10.1103/PhysRevLett.116.086601

Abstract

We study the magnetotransport properties of high-mobility holes in monolayer and bilayer WSe_{2}, which display well defined Shubnikov-de Haas (SdH) oscillations, and quantum Hall states in high magnetic fields. In both mono- and bilayer WSe_{2}, the SdH oscillations and the quantum Hall states occur predominantly at even filling factors, evincing a twofold Landau level degeneracy. The Fourier transform analysis of the SdH oscillations in bilayer WSe_{2} reveals the presence of two subbands localized in the top or the bottom layer, as well as negative compressibility. From the temperature dependence of the SdH oscillations we determine a hole effective mass of 0.45m_{0} for both mono- and bilayer WSe_{2}.