Inhomogeneous magnetism in the doped kagome lattice of LaCuO2.66

TL;DR

This study investigates the inhomogeneous magnetic properties of hole-doped LaCuO2.66's kagome lattice, revealing a complex interplay of insulating behavior, free spins, and frozen moments through various experimental techniques and simulations.

Contribution

It provides new insights into the inhomogeneous magnetism and cluster distribution in doped kagome lattices near the percolation threshold.

Findings

Activated behavior above ~180 K suggests narrow-gap semiconductor properties.

Presence of coexisting non-magnetic sites, free spins, and frozen moments indicates inhomogeneous magnetism.

Numerical simulations support a heterogeneous cluster distribution near the percolation threshold.

Abstract

The hole-doped kagome lattice of Cu2+ ions in LaCuO2.66 was investigated by nuclear quadrupole resonance (NQR), electron spin resonance (ESR), electrical resistivity, bulk magnetization and specific heat measurements. For temperatures above ~180 K, the spin and charge properties show an activated behavior suggestive of a narrow-gap semiconductor. At lower temperatures, the results indicate an insulating ground state which may or may not be charge ordered. While the frustrated spins in remaining patches of the original kagome lattice might not be directly detected here, the observation of coexisting non-magnetic sites, free spins and frozen moments reveals an intrinsically inhomogeneous magnetism. Numerical simulations of a 1/3-diluted kagome lattice rationalize this magnetic state in terms of a heterogeneous distribution of cluster sizes and morphologies near the site-percolation threshold.