Competing Ordering Modes in the Distorted Quantum Kagome Material Clinoatacamite Cu$_2$Cl(OH)$_3$

TL;DR

This study investigates the complex magnetic phases of clinoatacamite, a distorted kagome antiferromagnet, revealing multiple low-temperature phases driven by competing magnetic modes and structural distortions.

Contribution

It combines density-functional theory with experimental techniques to uncover the competing magnetic ordering modes in clinoatacamite, a key step in understanding frustrated quantum magnets.

Findings

Multiple magnetic phases below 18.1 K identified

Competition of antiferromagnetic modes explained complex behavior

Structural distortion influences magnetic ordering

Abstract

We have studied the magnetic properties of clinoatacamite Cu$_2$Cl(OH)$_3$, the parent compound of the quantum spin liquid candidate herbertsmithite and a longstanding puzzle among frustrated quantum magnets. As we reveal using density-functional theory, clinoatacamite belongs to the class of distorted kagome antiferromagnets with the kagome plane being embedded into a low-symmetry crystal structure. By means of thermodynamic measurements, muon spin rotation/relaxation as well as neutron diffraction on single crystals, we find a complex sequence of phases/regions below 18.1 K in zero magnetic field. We propose this complexity in multicritical clinoatacamite to arise from the competition of antiferromagnetic ordering modes from the underconstrained manifold of modes, which can lead to a metamagnetic texture in zero magnetic field.