Giant phonon anomalies in the proximate Kitaev quantum spin liquid α-RuCl3
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Tokyo Institute of Technology (Japan)
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Brookhaven National Lab. (BNL), Upton, NY (United States); Paul Scherrer Inst. (PSI), Villigen (Switzerland)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
- Brookhaven National Lab. (BNL), Upton, NY (United States)
The Kitaev quantum spin liquid epitomizes an entangled topological state, for which two flavors of fractionalized low-energy excitations are predicted: the itinerant Majorana fermion and the Z2 gauge flux. It was proposed recently that fingerprints of fractional excitations are encoded in the phonon spectra of Kitaev quantum spin liquids through a novel fractional-excitation-phonon coupling. Here, we detect anomalous phonon effects in α-RuCl3 using inelastic X-ray scattering with meV resolution. At high temperature, we discover interlaced optical phonons intercepting a transverse acoustic phonon between 3 and 7 meV. Upon decreasing temperature, the optical phonons display a large intensity enhancement near the Kitaev energy, JK~8 meV, that coincides with a giant acoustic phonon softening near the Z2 gauge flux energy scale. These phonon anomalies signify the coupling of phonon and Kitaev magnetic excitations in α-RuCl3 and demonstrates a proof-of-principle method to detect anomalous excitations in topological quantum materials.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States); Brookhaven National Laboratory (BNL), Upton, NY (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division; Gordon and Betty Moore Foundation; Japan Society for the Promotion of Science (JSPS)
- Grant/Contract Number:
- AC02-06CH11357; SC0012704; 21K13865; JP18H03678; GBMF9069; AC05-00OR22725
- OSTI ID:
- 1787494
- Alternate ID(s):
- OSTI ID: 1782548; OSTI ID: 1805025
- Report Number(s):
- BNL-221379-2021-JAAM; 161217
- Journal Information:
- Nature Communications, Vol. 12, Issue 1; ISSN 2041-1723
- Publisher:
- Nature Publishing GroupCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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