Abstract
Understanding phonons in α-RuCl3 is critical to analyze the controversy around the observation of the half-integer thermal quantum Hall effect. While many studies have focused on the magnetic excitations in α-RuCl3, its vibrational excitation spectrum has remained relatively unexplored. We investigate the phonon structure of α-RuCl3 via inelastic neutron-scattering experiments and density-functional-theory calculations. Our results show excellent agreement between experiment and first-principles calculations. After validating our theoretical model, we extrapolate the low-energy phonon properties. We find that the phonons in α-RuCl3 that either propagate or vibrate in the out-of-plane direction have significantly reduced velocities and therefore have the potential to dominate the observability of the elusive half-integer plateaus in the thermal Hall conductance. In addition, we use low-energy interlayer phonons to resolve the lowerature stacking structure of our large crystal of α-RuCl3, which we find to be consistent with that of the R3¯ space group, in agreement with neutron diffraction.
| Original language | English |
|---|---|
| Article number | 013067 |
| Journal | Physical Review Research |
| Volume | 4 |
| Issue number | 1 |
| DOIs | |
| State | Published - Mar 1 2022 |
Funding
This research used resources of the National Energy Research Scientific Computing Center (NERSC), a U.S. Department of Energy Office of Science User Facility operated under Contract No. DE-AC02-05CH11231. This research also used resources of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC05-00OR22725. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a nonexclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan . The authors are grateful to Satoshi Okamoto, Pontus Laurell, Mengxing Ye, Simon Thébaud, Peter Czjaka, and Lucas Lindsay for fruitful discussions and to Zach Morgan for his help with the extraction of the diffraction data. The work by T.B. was conducted at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. The work by A.B., K.D., S.E.N., and G.B.H. has been supported by the U.S. Department of Energy, Office of Science, National Quantum Information Science Research Centers, Quantum Science Center. The work by S.M. and J.Y. was supported by the U.S. Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division. K.D. was also supported by Purdue University, College of Science, Ralf Scharenberg Fellowship. D.M. acknowledges support from the Gordon and Betty Moore Foundation's EPiQS Initiative, Grant Number GBMF9069. A portion of this research used resources at the Spallation Neutron Source, a DOE Office of Science User Facility operated by the Oak Ridge National Laboratory.
| Funders | Funder number |
|---|---|
| CADES | |
| Data Environment for Science | |
| National Quantum Information Science Research Centers | |
| Quantum Science Center | |
| U.S. Department of Energy | DE-AC05-00OR22725, DE-AC02-05CH11231 |
| Gordon and Betty Moore Foundation | GBMF9069 |
| Office of Science | |
| Basic Energy Sciences | |
| Purdue University | |
| Division of Materials Sciences and Engineering |