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E8 Spectra of Quasi-One-Dimensional Antiferromagnet BaCo2V2O8 under Transverse Field



Haiyuan Zou, Y. Cui, Xiao Wang, Z. Zhang, J. Yang, Guangyong Xu, A. Okutani, M. Hagiwara, M. Matsuda, G. Wang, Giuseppe Mussardo, K. Hodsagi, M. Kormos, Zhangzhen He, S. Kimura, Rong Yu, Weiqiang Yu, Jie Ma, Jianda Wu


Exotic excitations can emerge in the vicinity of a quantum phase transition. When the quantum critical point of the one-dimensional (1D) transverse field Ising model is perturbed by a longitudinal magnetic field, it was predicted that its massive excitations are precisely described by the exceptional E8 Lie algebra. Here we show an unambiguous experimental realization of the massive E8 phase in the quasi-1D antiferromagnetic material BaCo2V2O8, via nuclear magnetic resonance and inelastic neutron scattering measurements, and detailed theoretical analysis. The large separation between the masked 1D and 3D quantum critical points of the system allows us to identify, for the first time, the full 8 single-particle E8 excitations as well as various multi-particle states in the spin excitation spectrum. Our results open new experimental route for exploring the dynamics of quantum integrable systems and physics beyond integrability, and thus bridge key physics in condensed matter and statistical field theory.
Physical Review Letters


neutron scattering, spin dynamics, quasi-one-dimensional antiferromagnet, E8 symmetry


Zou, H. , Cui, Y. , Wang, X. , Zhang, Z. , Yang, J. , Xu, G. , Okutani, A. , Hagiwara, M. , Matsuda, M. , Wang, G. , Mussardo, G. , Hodsagi, K. , Kormos, M. , He, Z. , Kimura, S. , Yu, R. , Yu, W. , Ma, J. and Wu, J. (2021), E<sub>8</sub> Spectra of Quasi-One-Dimensional Antiferromagnet BaCo<sub>2</sub>V<sub>2</sub>O<sub>8</sub> under Transverse Field, Physical Review Letters (Accessed May 31, 2023)
Created August 8, 2021, Updated September 26, 2022