Structure and magnetism of S = 1/2 kagome antiferromagnets NiCu3(OH)6Cl2 and CoCu3(OH)6Cl2

TL;DR

This study synthesizes and characterizes NiCu3(OH)6Cl2 and CoCu3(OH)6Cl2 kagome antiferromagnets, revealing spin glass behavior and the influence of magnetic ion substitution on magnetic properties and ground states.

Contribution

First synthesis and structural characterization of Ni and Co kagome antiferromagnets showing spin glass behavior and effects of magnetic ion substitution.

Findings

Both compounds have similar crystal structures to ZnCu3(OH)6Cl2.

Spin glass transition observed at low temperatures.

Magnetic ion substitution affects interlayer exchange and ground state.

Abstract

We have successfully synthesized S = 1/2 kagome antiferromagnets MCu3(OH)6Cl2 (M = Ni and Co) by hydrothermal method with rotating pressure vessel. Structural characterization shows that both compounds have the similar crystal structure as ZnCu3(OH)6Cl2 with R-3m symmetry. Similar to ZnCu3(OH)6Cl2, the compounds show no obvious hysteresis at 2 K. A spin glass transition is found in both NiCu3(OH)6Cl2 and CoCu3(OH)6Cl2 at low temperatures (6.0 and 3.5 K respectively) by AC susceptibility measurements. It indicates no long-range magnetic order and a strong spin frustration. The substitution of Zn2+ by magnetic ions Ni2+ or Co2+, effectively enhances interlayer exchange coupling and changes the ground state of the kagome spin system.