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arXiv · 1908.08403

Novel Excitations near Quantum Criticality in Geometrically Frustrated Antiferromagnet CsFeCl$_{3}$

Shohei Hayashida·Masashige Matsumoto·Masato Hagihala·Nobuyuki Kurita·Hidekazu Tanaka·Shinichi Itoh·Tao Hong·Minoru Soda·Yoshiya Uwatoko·Takatsugu Masuda
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Abstract

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.

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Shohei Hayashida, Masashige Matsumoto, Masato Hagihala, Nobuyuki Kurita, Hidekazu Tanaka, Shinichi Itoh, Tao Hong, Minoru Soda, Yoshiya Uwatoko, Takatsugu Masuda. 2019-08-22. Novel Excitations near Quantum Criticality in Geometrically Frustrated Antiferromagnet CsFeCl$_{3}$. https://arxiv.org/abs/1908.08403

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