Dynamics of quantum spin liquid and spin solid phases in IPA-CuCl3 under field

TL;DR

This study investigates the magnetic field-induced quantum phase transition in IPA-CuCl3, revealing magnon condensation, changes in spectrum, and the emergence of new spectral features through neutron scattering.

Contribution

It provides detailed experimental insights into magnon behavior and spectrum evolution across the quantum phase transition in a quasi-one-dimensional antiferromagnet.

Findings

Magnon condensation and long-range order at H_c=9.5 T

Shift of critical wave vector of magnon spectrum truncation

Significant reduction of magnon bandwidths in the ordered phase

Abstract

Inelastic and elastic neutron scattering is used to study spin correlations in the quasi-one dimensional quantum antiferromagnet IPA-CuCl3 in strong applied magnetic fields. A condensation of magnons and commensurate transverse long-range ordering is observe at a critical filed $H_c=9.5$ T. The field dependencies of the energies and polarizations of all magnon branches are investigated both below and above the transition point. Their dispersion is measured across the entire 1D Brillouin zone in magnetic fields up to 14 T. The critical wave vector of magnon spectrum truncation [Masuda et al., Phys. Rev. Lett. 96, 047210 (2006)] is found to shift from h_c 0.35 at H>H_c. A drastic reduction of magnon bandwidths in the ordered phase [Garlea et al., Phys. Rev. Lett. 98, 167202 (2007)] is observed and studied in detail. New features of the spectrum, presumably related to this bandwidth collapse, are observed just above the transition field.