Observation of Unusual Magnetoelastic Effects in a Quasi-1D Spiral Magnet

TL;DR

This study investigates the complex spin and lattice interactions in the quasi-1D spiral magnet CuBr2, revealing unusual magnetoelastic effects likely due to hybrid excitations or lattice quadrumerization, with implications for understanding low-dimensional magnetic systems.

Contribution

It provides the first detailed Raman and neutron spectroscopy analysis of magnetoelastic effects in CuBr2, highlighting potential hybrid spin-lattice excitations and lattice distortions associated with spiral magnetism.

Findings

Observation of broad Raman bands near phonon energies at the magnetic wave vector

Enhanced Raman intensity at the spiral magnetic ordering temperature

Evidence suggesting hybrid spin-lattice excitations or lattice quadrumerization

Abstract

We present a systematic study of spin and lattice dynamics in the quasi-one-dimensional spiral magnet CuBr2, using Raman scattering in conjunction with infrared and neutron spectroscopy. Along with the development of spin correlations upon cooling, we observe a rich set of broad Raman bands at energies that correspond to phonon-dispersion energies near the one-dimensional magnetic wave vector. The low-energy bands further exhibit a distinct intensity maximum at the spiral magnetic ordering temperature. We attribute these unusual observations to two possible underlying mechanisms: (1) formation of hybrid spin-lattice excitations, and/or (2) "quadrumerization" of the lattice caused by spin-singlet entanglement in competition with the spiral magnetism.