# Magnetic structure and spin waves in the frustrated ferro-antiferromagnet Pb$_2$VO(PO$_4$)$_2$

## TL;DR

This study investigates the magnetic structure and spin wave excitations in Pb$_2$VO(PO$_4$)$_2$, revealing a more complex interaction network and reduced frustration compared to earlier models, using neutron scattering and ESR techniques.

## Contribution

It introduces a revised model with at least four exchange couplings, challenging previous simpler square lattice assumptions for this frustrated ferromagnet.

## Key findings

- Inconsistent with simple square lattice model
- Requires at least four exchange couplings
- Magnetic frustration is smaller than previously estimated

## Abstract

Single crystal neutron diffraction, inelastic neutron scattering and electron spin resonance experiments are used to study the magnetic structure and spin waves in Pb$_2$VO(PO$_4$)$_2$, a prototypical layered $S=1/2$ ferromagnet with frustrating next nearest neighbor antiferromagnetic interactions. The observed excitation spectrum is found to be inconsistent with a simple square lattice model previously proposed for this material. At least four distinct exchange coupling constants are required to reproduce the measured spin wave dispersion. The degree of magnetic frustration is correspondingly revised and found to be substantially smaller than in all previous estimates.