Continuum excitations in a spin-supersolid on a triangular lattice

TL;DR

This study investigates the magnetic excitations in a spin-supersolid on a triangular lattice, revealing a broad continuum at zero field and sharp modes under a magnetic field, indicating complex quantum states and potential proximity to a Dirac spin liquid.

Contribution

The paper provides experimental evidence of continuum excitations in a spin-supersolid and suggests a possible connection to a Dirac spin liquid state, advancing understanding of quantum magnetism.

Findings

Broad multi-particle continuum at zero field

Sharp spin wave modes in a magnetic field

Excitation minima at Brillouin zone M-points

Abstract

Magnetic, thermodynamic, neutron diffraction and inelastic neutron scattering are used to study spin correlations in the easy-axis XXZ triangular lattice magnet K2Co(SeO3)2. Despite the presence of quasi-2D "supersolid" magnetic order, the low-energy excitation spectrum contains no sharp modes and is instead a broad and structured multi-particle continuum. Applying a weak magnetic field drives the system into an m = 1/3 fractional magnetization plateau phase and restores sharp spin wave modes. To some extent, the behavior at zero field can be understood in terms of spin wave decay. However, the presence of clear excitation minima at the M-points of the Brillouin zone suggest that the spinon language may provide a more adequate description, and signals a possible proximity to a Dirac spin liquid state.