Barlowite as a canted antiferromagnet: theory and experiment

TL;DR

This paper combines theoretical calculations and experimental measurements to analyze the magnetic properties of barlowite, revealing its canted antiferromagnetic order due to complex exchange interactions.

Contribution

It provides a detailed theoretical and experimental study of barlowite's magnetic structure, highlighting its canted antiferromagnetism driven by specific exchange couplings and Dzyaloshinskii-Moriya interactions.

Findings

Barlowite exhibits canted antiferromagnetic order below 15 K.

Density functional theory accurately predicts exchange interactions in barlowite.

Magnetic susceptibility confirms the magnetic ordering observed theoretically.

Abstract

We investigate the structural, electronic and magnetic properties of the newly synthesized mineral barlowite Cu4(OH)6FBr which contains Cu2+ ions in a perfect kagome arrangement. In contrast to the spin-liquid candidate herbertsmithite ZnCu3(OH)6Cl2, kagome layers in barlowite are perfectly aligned due to the different bonding environments adopted by F- and Br- compared to Cl-. We perform density functional theory calculations to obtain the Heisenberg Hamiltonian parameters of Cu4(OH)6FBr which has a Cu2+ site coupling the kagome layers. The 3D network of exchange couplings together with a substantial Dzyaloshinskii-Moriya coupling lead to canted antiferromagnetic ordering of this compound at TN=15 K as observed by magnetic susceptibility measurements on single crystals.