The nature of spin excitations in the one-third magnetization plateau phase of Ba3CoSb2O9

Y Kamiya; L Ge; Tao Hong; Y Qiu; D L Quintero-Castro; Z Lu; H B Cao; M Matsuda; E S Choi; C D Batista; M Mourigal; H D Zhou; J Ma

doi:10.1038/s41467-018-04914-1

The nature of spin excitations in the one-third magnetization plateau phase of Ba₃CoSb₂O₉

Nat Commun. 2018 Jul 10;9(1):2666. doi: 10.1038/s41467-018-04914-1.

Authors

Y Kamiya¹, L Ge², Tao Hong³, Y Qiu⁴, D L Quintero-Castro⁵, Z Lu⁵, H B Cao³, M Matsuda³, E S Choi⁶, C D Batista^{7

8}, M Mourigal², H D Zhou^{6

7}, J Ma^{9

10

11}

Affiliations

¹ Condensed Matter Theory Laboratory, RIKEN, Wako, Saitama, 351-0198, Japan. yoshitomo.kamiya@riken.jp.
² School of Physics, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
³ Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
⁴ NIST Centre for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA.
⁵ Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109, Berlin, Germany.
⁶ National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL, 32310, USA.
⁷ Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA.
⁸ Neutron Scattering Division and Shull-Wollan Center, Oak Ridge National Laboratory, Oak Ridge, TN, 37831, USA.
⁹ Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA. jma3@sjtu.edu.cn.
¹⁰ Key Laboratory of Artificial Structures and Quantum Control, Department of Physics and Astronomy, Shanghai Jiao Tong University, 200240, Shanghai, China. jma3@sjtu.edu.cn.
¹¹ Collaborative Innovation Center of Advanced Microstructures, 210093, Nanjing, Jiangsu, China. jma3@sjtu.edu.cn.

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.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.