Investigation of materials that exhibit quantum phase transition provides valuable insights into fundamental problems in physics. We present neutron scattering under pressure in a triangular-lattice antiferromagnet which has a quantum disorder in the low-pressure phase and a noncollinear structure in the high-pressure phase. The neutron spectrum continuously evolves through the critical pressure; a single mode in the disordered state becomes soft with the pressure, and it splits into gapless and gapped modes in the ordered phase. Extended spin-wave theory reveals that the longitudinal and transverse fluctuations of spins are hybridized in the modes because of the noncollinearity, and novel magnetic excitations are formed. We report a new hybridization of the phase and amplitude fluctuations of the order parameter in a spontaneously symmetry-broken state.
@article{arxiv.1908.08403,
title = {Novel Excitations near Quantum Criticality in Geometrically Frustrated Antiferromagnet CsFeCl$_{3}$},
author = {Shohei Hayashida and Masashige Matsumoto and Masato Hagihala and Nobuyuki Kurita and Hidekazu Tanaka and Shinichi Itoh and Tao Hong and Minoru Soda and Yoshiya Uwatoko and Takatsugu Masuda},
journal= {arXiv preprint arXiv:1908.08403},
year = {2019}
}
Comments
Supplementary material comes first and main text is followed. 12 pages, 3 figures and 1 table for supplementary material. 13 pages and 4 figures for main text