Static and Dynamic Magnetic Response of Fragmented Haldane-like Spin Chains in Layered Li3Cu2SbO6

TL;DR

This study investigates the magnetic properties of layered Li3Cu2SbO6, revealing a fragmented Haldane chain structure with coexisting magnetic states and significant defects, through comprehensive diffraction and magnetic measurements.

Contribution

It provides the first detailed analysis of the magnetic response of Li3Cu2SbO6, identifying a fragmented Haldane chain scenario with high defect concentration and mixed magnetic contributions.

Findings

Verified space group C2/m with halved unit cell volume

Identified two magnetic contributions: quasi-free spins and spin-gapped subsystem

Estimated about 17% defect concentration leading to S=1/2 edge states

Abstract

The structure and the magnetic properties of layered Li3Cu2SbO6 are investigated by powder X-ray diffraction, static susceptibility, and electron spin resonance studies up to 330 GHz. The XRD data experimentally verify the space group C2/m with halved unit cell volume in contrast to previously reported C2/c. In addition, the data show significant Li/Cu-intersite exchange. Static magnetic susceptibility and ESR measurements show two magnetic contributions, i.e. quasi-free spins at low-temperature and a spin-gapped magnetic subsystem, with about half of the spins being associated to each subsystem. The data suggest ferromagnetic-antiferromagnetic alternating chains with JFM = -285 K and JAFM = 160 K with a significant amount of Li-defects in the chains. The results are discussed in the scenario of fragmented 1D S = 1 AFM chains with a rather high defect concentration of about 17% and associated S = 1/2 edge states of the resulting finite Haldane chains.