Abstract
Close to the quantum critical point of the transverse-field Ising spin-chain model, an exotic dynamic spectrum was predicted to emerge upon a perturbative longitudinal field. The dynamic spectrum consists of eight particles and is governed by the symmetry of the Lie algebra. Here we report on high-resolution terahertz spectroscopy of quantum spin dynamics in the ferromagnetic Ising-chain material . At 0.25 K in the magnetically ordered phase we identify characteristics of the first six particles, to , and the two-particle continuum in an applied transverse magnetic field of , before the three-dimensional magnetic order is suppressed above . The observation of the higher-energy particles above the low-energy two-particle continua features quantum many-body effects in the exotic dynamic spectrum.
- Received 23 June 2020
- Revised 4 September 2020
- Accepted 8 September 2020
DOI:https://doi.org/10.1103/PhysRevB.102.104431
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article's title, journal citation, and DOI.
Published by the American Physical Society