Neutron Scattering Study on Pressure-induced Quantum Phase Transition by Means of Triple-Axis and Time-of-Flight Spectrometers

Abstract

A pressure-induced quantum phase transition in the triangular antiferromagnet CsFeCl₃ has been studied by means of both triple-axis and time-of-flight neutron spectrometers. Inelastic neutron scattering experiments were performed to measure entire spin spectra through the transition and their pressure dependence. It is demonstrated that in the quantum disordered phase, the magnetic excitation is softened by applying pressures. A spin wave excitation is observed in the ordered phase. Calculation of the spin spectra proves that the transverse and longitudinal spin fluctuations are hybridized in the ordered state. In addition, it is found that the hybridization is remarkably enhanced near the quantum critical point.