Nonlinear excitations in CsNiF3 in magnetic fields perpendicular to the easy plane

TL;DR

This study investigates the nonlinear spin excitations in CsNiF3 under perpendicular magnetic fields, confirming theoretical predictions of double peak specific heat structures through experimental and numerical analysis.

Contribution

It provides new experimental and numerical evidence for nonlinear spin modes in CsNiF3 with magnetic fields perpendicular to the easy plane, improving understanding of magnetic excitations.

Findings

Confirmation of double peak specific heat structure

Negligible demagnetizing effects in the measurements

Better agreement between data and numerical predictions than previous studies

Abstract

Experimental and numerical studies of the magnetic field dependence of the specific heat and magnetization of single crystals of CsNiF3 have been performed at 2.4 K, 2.9 K, and 4.2 K in magnetic fields up to 9 T oriented perpendicular to the easy plane. The experimental results confirm the presence of the theoretically predicted double peak structure in the specific heat arising from the formation of nonlinear spin modes. The demagnetizing effects are found to be negligible, and the overall agreement between the data and numerical predictions is better than reported for the case when the magnetic field was oriented in the easy plane. Demagnetizing effects might play a role in generating the difference observed between theory and experiment in previous work analyzing the excess specific heat using the sine-Gordon model.