Effect of a structural disorder on the magnetic properties of the sodium–cobalt tellurate Na3.70Co1.15TeO6

Abstract

A new layered oxide, sodium–cobalt tellurate Na_3.70Co_1.15TeO₆, is synthesized and structurally characterized, and its static and dynamic magnetic properties are studied. This compound has a new monoclinic structure type with quasi-one-dimensional cation ordering in magnetically active layers. This compound is antiferromagnetically ordered at a Néel temperature T_N ~ 3.3 K, and the temperature and field dependences of magnetization suggest competing antiferromagnetic and ferromagnetic interactions. EPR spectroscopy reveals complex spin dynamics when temperature changes and the presence of two different paramagnetic centers, which is attributed to the existence of two structurally nonequivalent (regular and antisite) positions for magnetic Co²⁺ ions.