Square-lattice magnetism of diaboleite Pb2Cu(OH)4Cl2

TL;DR

This study investigates the quasi-two-dimensional magnetism of diaboleite, revealing a diluted square lattice Heisenberg model with antiferromagnetic order below 11 K and no signs of magnetic frustration.

Contribution

It provides the first detailed magnetic characterization of diaboleite, linking its structure to a diluted square lattice Heisenberg model with specific exchange parameters.

Findings

Magnetic susceptibility fits a diluted square lattice Heisenberg model.

Long-range antiferromagnetic order observed below 11 K.

No evidence of magnetic frustration found.

Abstract

We report on the quasi-two-dimensional magnetism of the natural mineral diaboleite Pb2Cu(OH)4Cl2 with a tetragonal crystal structure, which is closely related to that of the frustrated spin-1/2 magnet PbVO3. Magnetic susceptibility of diaboleite is well described by a Heisenberg spin model on a diluted square lattice with the nearest-neighbor exchange of J~35 K and about 5% of non-magnetic impurities. The dilution of the spin lattice reflects the formation of Cu vacancies that are tolerated by the crystal structure of diaboleite. The weak coupling between the magnetic planes triggers the long-range antiferromagnetic order below TN~11 K. No evidence of magnetic frustration is found. We also analyze the signatures of the long-range order in heat-capacity data, and discuss the capability of identifying magnetic transitions with heat-capacity measurements.