# Magnetic and dielectric order in the kagome-like francisite Cu$_3$Bi(SeO$_3$)$_2$O$_2$Cl

## TL;DR

This study reveals the magnetic and dielectric properties of kagome-like Cu$_3$Bi(SeO$_3$)$_2$O$_2$Cl, identifying its magnetic structure, structural transition, and multiferroic behavior through neutron scattering and dielectric measurements.

## Contribution

It provides the first detailed magnetic structure and microscopic understanding of anisotropic exchange in Cu$_3$Bi(SeO$_3$)$_2$O$_2$Cl, clarifying its multiferroic properties.

## Key findings

- Determined the magnetic structure below 25 K.
- Identified a structural transition at 115 K.
- Revealed significant anisotropic exchange interactions.

## Abstract

We report a single-crystal neutron diffraction and inelastic neutron scattering study on the spin 1/2 cuprate Cu$_3$Bi(SeO$_3$)$_2$O$_2$Cl, complemented by dielectric and electric polarization measurements. The study clarifies a number of open issues concerning this complex material, whose frustrated interactions on a kagome-like lattice, combined with Dzyaloshinskii-Moriya interactions, are expected to stabilize an exotic canted antiferromagnetic order. In particular, we determine the nature of the structural transition occurring at 115 K, the magnetic structure below 25 K resolved in the updated space group, and the microscopic ingredients at the origin of this magnetic arrangement. This was achieved by an analysis of the measured gapped spin waves, which signifies the need of an unexpected and significant anisotropic exchange beyond the proposed Dzyaloshinskii-Moriya interactions. Finally, we discuss the mutliferroic properties of this material with respect to the space group symmetries.