# Magnetization process of atacamite: a case of weakly coupled $S = 1/2$ sawtooth chains

## TL;DR

This study combines experimental and theoretical methods to analyze atacamite's magnetic behavior, revealing a unique magnetization plateau and complex field-dependent magnetic order due to weakly coupled sawtooth chains.

## Contribution

It provides a detailed model of atacamite's anisotropic sawtooth chains and uncovers a novel magnetization process unrelated to known plateaus.

## Key findings

- Observation of a magnetization plateau at about half saturation
- Identification of a field-driven canting mechanism in weakly coupled chains
- Full characterization of the antiferromagnetic order in atacamite

## Abstract

We present a combined experimental and theoretical study of the mineral atacamite Cu$_2$Cl(OH)$_3$. Density functional theory yields a Hamiltonian describing anisotropic sawtooth chains with weak 3D connections. Experimentally, we fully characterize the antiferromagnetically ordered state. Magnetic order shows a complex evolution with the magnetic field, while, starting at 31.5 T, we observe a plateau-like magnetization at about $M_{\rm sat}/2$. Based on complementary theoretical approaches, we show that the latter is unrelated to the known magnetization plateau of a sawtooth chain. Instead, we provide evidence that the magnetization process in atacamite is a field-driven canting of a 3D network of weakly coupled sawtooth chains that form giant moments.