Abstract
Magnetization plateaus in quantum magnets - where bosonic quasiparticles crystallize into emergent spin superlattices - are spectacular yet simple examples of collective quantum phenomena escaping classical description. While magnetization plateaus have been observed in a number of spin-1/2 antiferromagnets, the description of their magnetic excitations remains an open theoretical and experimental challenge. Here, we investigate the dynamical properties of the triangular-lattice spin-1/2 antiferromagnet Ba3CoSb2O9 in its one-third magnetization plateau phase using a combination of nonlinear spin-wave theory and neutron scattering measurements. The agreement between our theoretical treatment and the experimental data demonstrates that magnons behave semiclassically in the plateau in spite of the purely quantum origin of the underlying magnetic structure. This allows for a quantitative determination of Ba3CoSb2O9 exchange parameters. We discuss the implication of our results to the deviations from semiclassical behavior observed in zero-field spin dynamics of the same material and conclude they must have an intrinsic origin.
| Original language | English |
|---|---|
| Article number | 2666 |
| Journal | Nature Communications |
| Volume | 9 |
| Issue number | 1 |
| DOIs | |
| State | Published - Dec 1 2018 |
Funding
We thank H. Tanaka, A. Chernyshev, and O. Starykh for valuable discussions. J.M. acknowledges support of the Ministry of Science and Technology of China (2016YFA0300500) and from NSF China (11774223). Y. K. acknowledges financial support by JSPS Grants-in-Aid for Scientific Research under Grant No. JP16H02206. The work at Georgia Tech was supported by ORAUs Ralph E. Powe Junior Faculty Enhancement Award (M. Mourigal) and NSF-DMR-1750186 (L. G. and M. Mourigal). C. D. B. acknowledges financial support from the Los Alamos National Laboratory Directed Research and Development program and from the Lincoln Chair of Excellence in Physics. H. D. Z. acknowledges support from NSF-DMR-1350002. The work performed in NHMFL was supported by NSF-DMR-1157490 and the State of Florida. We are grateful for the access to the neutron beam time at the neutron facilities at NCNR, BER-II at Helmholtz-Zentrum Berlin and HFIR operated by ORNL. The research at HFIR at ORNL was sponsored by the Scientific User Facilities Division (T. H., H. B. C., and M. Matsuda), Office of Basic Energy Sciences, U.S. DOE. Access to MACS was provided by the Center for High Resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology and the National Science Foundation under Agreement No. DMR-1508249. We thank H. Tanaka, A. Chernyshev, and O. Starykh for valuable discussions. J.M. acknowledges support of the Ministry of Science and Technology of China (2016YFA0300500) and from NSF China (11774223). Y. K. acknowledges financial support by JSPS Grants-in-Aid for Scientific Research under Grant No. JP16H02206. The work at Georgia Tech was supported by ORAU’s Ralph E. Powe Junior Faculty Enhancement Award (M. Mourigal) and NSF-DMR-1750186 (L. G. and M. Mourigal). C. D. B. acknowledges financial support from the Los Alamos National Laboratory Directed Research and Development program and from the Lincoln Chair of Excellence in Physics. H. D. Z. acknowledges support from NSF-DMR-1350002. The work performed in NHMFL was supported by NSF-DMR-1157490 and the State of Florida. We are grateful for the access to the neutron beam time at the neutron facilities at NCNR, BER-II at Helmholtz-Zentrum Berlin and HFIR operated by ORNL. The research at HFIR at ORNL was sponsored by the Scientific User Facilities Division (T. H., H. B. C., and M. Matsuda), Office of Basic Energy Sciences, U.S. DOE. Access to MACS was provided by the Center for High Resolution Neutron Scattering, a partnership between the National Institute of Standards and Technology and the National Science Foundation under Agreement No. DMR-1508249.