Investigation of the spin-1 honeycomb antiferromagnet BaNi$_2$V$_2$O$_8$ with easy plane anisotropy

TL;DR

This study comprehensively characterizes the magnetic excitations and anisotropies of the two-dimensional S=1 honeycomb antiferromagnet BaNi$_2$V$_2$O$_8$, revealing its highly two-dimensional nature and easy-plane anisotropy.

Contribution

The paper provides detailed experimental data and analysis of magnetic interactions and anisotropies in BaNi$_2$V$_2$O$_8$, establishing it as a candidate for studying vortex excitations and KT phenomena.

Findings

Magnetic excitation spectrum is dispersionless between layers and disperses within the plane.

First- and second-neighbor exchange interactions are antiferromagnetic with specified ranges.

Interplane coupling is four orders of magnitude weaker than intraplane interactions.

Abstract

The magnetic properties of the two-dimensional, S=1 honeycomb antiferromagnet BaNi$_2$V$_2$O$_8$ have been comprehensively studied using DC susceptibility measurements and inelastic neutron scattering techniques. The magnetic excitation spectrum is found to be dispersionless within experimental resolution between the honeycomb layers, while it disperses strongly within the honeycomb plane where it consists of two gapped spin-wave modes. The magnetic excitations are compared to linear spin-wave theory allowing the Hamiltonian to be determined. The first- and second-neighbour magnetic exchange interactions are antiferromagnetic and lie within the ranges 10.90meV$\le$J$_n$$\le$13.35 meV and 0.85meV$\le$J$_{nn}$$\le$1.65 meV respectively. The interplane coupling J$_{out}$ is four orders of magnitude weaker than the intraplane interactions, confirming the highly two-dimensional magnetic behaviour of this compound. The sizes of the energy gaps are used to extract the magnetic anisotropies and reveal substantial easy-plane anisotropy and a very weak in-plane easy-axis anisotropy. Together these results reveal that BaNi$_2$V$_2$O$_8$ is a candidate compound for the investigation of vortex excitations and Berezinsky-Kosterliz-Thouless phenomenona.