Eur. Phys. J. B (2013) 86: 248
https://doi.org/10.1140/epjb/e2013-30668-4

Regular Article

Magnetic properties of a family of quinternary oxalates^*

¹ Institut Néel, CNRS & Université Joseph Fourier, BP 166, 38042 Grenoble Cedex 9, France
² Institute for Theoretical Physics, University of Würzburg, 97070 Würzburg, Germany
³ Institut Laue Langevin, BP 156, 38042 Grenoble Cedex 9, France
⁴ University Glasgow, School of Chemistry, Glasgow G12 8QQ, Scotland
⁵ University Cambridge, Chem Lab, Cambridge CB2 1EW, England
⁶ Institute of Inorganic Chemistry, Karlsruhe Institute of Technology, Engesserstrasse 15, 76131 Karlsruhe, Germany
⁷ Institute for Nanotechnologie, Karlsruhe Institute of Technology, Postfach 3640, 76021 Karlsruhe, Germany

^a e-mail: elsa.lhotel@grenoble.cnrs.fr

Received: 24 July 2012
Received in final form: 20 March 2013
Published online: 6 June 2013

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 Fe^II 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°. A remarkable magnetic behavior emerges below the Néel 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.