Stripe order and spin dynamics in triangular-lattice antiferromagnet KErSe$_{2}$: A single-crystal study with a theoretical description

TL;DR

This study investigates the magnetic properties of KErSe$_{2}$, revealing stripe order and spin-wave excitations driven by anisotropic interactions, with insights supported by neutron scattering and theoretical modeling.

Contribution

First comprehensive single-crystal analysis of KErSe$_{2}$ showing stripe order and spin dynamics explained by anisotropic spin interactions.

Findings

Long-range stripe order below 0.2 K

Weak interlayer coupling with negligible z-direction modulation

Well-defined spin-wave dispersion with a 0.03 meV gap

Abstract

The rare-earth triangular-lattice chalcogenide is a great platform for exploring both spin liquids and novel magnetic orders with anisotropic spin interactions and magnetic frustrations. Here, we report the thermodynamic and neutron scattering measurements of rare-earth triangular-lattice chalcogenide KErSe$_{2}$, using single-crystal samples. Our experiments revealed a long-range stripe order below 0.2 K. Although the magnetic order was three-dimensional, magnetic excitations exhibited negligible modulation along the z direction, indicating very weak interlayer coupling. Furthermore, magnetic excitation developed a well-defined spin-wave dispersion with a gap of $\sim$0.03 meV at M points. Both the stripe order and spin-wave excitations could be quantitatively understood from the anisotropic spin interactions of the Er$^{3+}$ Kramers doublets.