Lattice symmetry breaking effects on the Raman phonon spectra of Kitaev magnet α-RuCl<sub>3</sub>

ORAL

Abstract

The honeycomb lattice of α-RuCl3 is a potential candidate to study the Kitaev model. The predicted ground state for such a model is a Quantum Spin Liquid. There is significant interest in studying the Kitaev interaction in α-RuCl3, which orders antiferromagnetically below 6 K. Within a single layer, the honeycomb lattice exhibits a small distortion in the b direction, causing the symmetry to be reduced from hexagonal to orthorhombic. The possible effects of this broken in-plane honeycomb symmetry on the Kitaev interactions are not well understood. To this end, we utilize Raman spectroscopy to study the distortion by identifying splittings of the phonon modes. The polarization-resolved phonon spectra of α-RuCl3 as a function of the crystal orientation, both with the polarization parallel and perpendicular to the quasi-honeycomb plane will be described. Subtle shifts in the phonon peak frequencies were observed as a function of the orientation angle that can be explained by the distortion. A combination of group theory analysis and Laue X-ray diffraction were performed to determine the symmetry of each phonon mode. This methodology uniquely confirms that the point group of α-RuCl3 is 2/m.

*The work from OSU is supported by the NSF MRSEC, under grant DMR-1420451

–

Presenters

  • Thuc Mai

    • Physics, Ohio State University

Authors

  • Thuc Mai

    • Physics, Ohio State University

  • Amber McCreary

    • Nanoscale Spectroscopy Group, National Institute of Standards and Technology
    • Engineering Physics Division, National Institute of Standards and Technology

  • Paige Lampen-Kelley

    • Material Science and Engineering, University of Tennessee
    • Materials Science and Engineering, University of Tennessee
    • Materials Science and Technology Division, Oak Ridge National Laboratory

  • Jeffrey Simpson

    • Towson University
    • Physics, Astronomy and Geosciences, Towson University

  • Stephen Nagler

    • Oak Ridge National Laboratory (USA)
    • Oak Ridge National Laboratory
    • Oak Ridge National Lab
    • Neutron Scattering Division, Oak Ridge National Laboratory

  • David Mandrus

    • Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee, 37831, USA
    • Materials Science and Engineering, University of Tennessee

  • Angela Hight Walker

    • NIST
    • Nanoscale Device Characterization Division, National Institute of Standards and Technology
    • National Institute of Standards and Technology
    • Nanoscale Device Characterization Division, Physical Measurement Laboratory, National Institute of Standards and Technology
    • Nanoscale Spectroscopy Group, National Institute of Standards and Technology
    • Engineering Physics Division, National Institute of Standards and Technology

  • Rolando Valdes Aguilar

    • Department of Physics, The Ohio State University
    • Physics, Ohio State University