Magnetic properties of a family of quinternary oxalates

TL;DR

This study investigates the magnetic behavior of four quinternary oxalates with kagome lattice structures, revealing complex low-temperature dynamics and domain wall phenomena influenced by anisotropy and connectivity.

Contribution

It provides new insights into the magnetic ordering and slow spin dynamics in quinternary oxalates with kagome lattices, highlighting the role of anisotropy and lattice connectivity.

Findings

All compounds order antiferromagnetically below Néel temperature.

Domain walls intersect kagome planes, creating free spin strings.

Unusual slow spin dynamics observed via AC susceptibility.

Abstract

We report on the magnetic properties of four isomorphous compounds of a family of quinternary oxalates down to 60 mK. In all these materials, the magnetic FeII ions with a strong magneto-crystalline anisotropy form a distorted kagome lattice, topologically equivalent to a perfect kagome one if nearest-neighbor interactions only are considered. All the compounds order at low temperature in an antiferromagnetic arrangement with magnetic moments at 120{\deg}. A remarkable magnetic behavior emerges below the N\'eel temperature in three compounds (with inter-kagome-layer Zr, Sn, Fe but not with Al): the spin anisotropy combined with a low exchange path network connectivity lead to domain walls intersecting the kagome planes through strings of free spins. These produce an unfamiliar slow spin dynamics in the ordered phase observed by AC susceptibility, evolving from exchange-released spin-flips towards a cooperative behavior on decreasing the temperature.