Temperature and Magnetic Field Effects on the Raman Spectra of TaSe$_{\mathrm{2}}$

POSTER

Abstract

In bulk form, TaSe$_{\mathrm{2}}$ exhibits transitions between commensurate and incommensurate charge-density wave (CDW) phases, and is attracting interest for advance device applications. In order to explore the evolution of the groundstate CDW phase, mechanical exfoliation of bulk crystals provides freshly cleaved surfaces and may be used to prepare few- to single-layer flakes. In the present work, we extended our opto-thermal Raman measurements [1] on MoS$_{\mathrm{2}}$ to include other TMDs, specifically TaSe$_{\mathrm{2}}$, in both \textit{1T} and \textit{2H} crystallographic phases. A novel, magneto-Raman microscope system affords measurement of low-frequency (down to 10cm$^{\mathrm{-1}})$ vibrational modes as a function of both temperature (\textasciitilde 10K to 300K) and magnetic field (0T to 9T). The dependence of the observed Raman-active phonons on temperature and magnetic field will be discussed and compared with earlier results on MoS$_{\mathrm{2}}$. Specifically, we observe the appearance of low-frequency, zone-folded modes in the CDW state, which soften with temperature similar to the higher frequency, in-plane $E_{2g}$ mode. Additionally, magnetic-field dependence, including Faraday rotation in the micro-crystal insert will be discussed.

Authors

  • J. Harding

    Graduate Student

  • Shahab Derakhshan

    Drexel University, Univ of Delaware, Princeton University, Naval Surface Warfare Center\Carderock Division\West Bethesda site, Naval Surface Warfare Center and Georgetown Univ., Dept. of Physics and Astronomy, University of Delaware, Dept. of Physics and Astronomy, University of Deleware, Dept. of Physics and Astronomy, University of Nevada-Reno, university of Delaware, Contributors, Department of Physics, Astronomy and Geosciences, Towson University, Choice Research Group, Univ of the Sciences in Philadephia, Rutgers Univ, National Institute of Standards and Technology, Department of Chemistry, West Chester University, West Chester, PA 19383, Bucknell University, Towson University, University of Maryland, College of William and Mary, Naval Research Laboratory, Department of Physics, Villanova University, Department of Chemistry, Faculty of Medicine, University of Brescia, Department of Chemistry, State University of New York at Potsdam, Delaware State University DE, NIH Bethesda MD, Wilmington Friends School DE, University Of Rochester NY, Delaware State University, Department of Physics and Astronomy,West Virginia University, The National Energy Technology Laboratory, Non-tenure track professor at research institution, Government Sponsored Laboratory, Research and Development at Industrial Company, Tenure-track Professor at 4 yr college, Department of Physics and Astronomy and Department of Chemistry and Biochemistry, University of Delaware, Biology and Soft Matter Division, Oak Ridge National Laboratory, and Department of Physics and Astronomy, The University of Tennessee, Biology and Soft Matter Division, Oak Ridge National Laboratory, Lehigh Univ, Johns Hopkins Univ, NIST, GMU, GWU, Lock Haven University of PA, Univ of Maryland-Balt County; Center for Nanoscale Materials, Argonne National Laboratory, Department of Chemistry, Northwestern University, Univ of Maryland-Balt County, Pennsylvania State University, BAE Systems, Inc., Nashua, New Hampshire 03061, Department of Physics, West Virginia University, Morgantown, West Virginia, 26506-6315, California State University, Long Beach

  • J. R. Simpson

    Contributors