Thermal Properties of Dysprosium Aluminum Garnet near the Néel Temperature

Abstract

Measurements of the specific heat of Dy3Al5O12 at temperatures between 1.2° and 4°K are described. A sharp λ anomaly was found at 2.49°K, and this is discussed in terms of an unusual type of antiferromagnetic ordering previously deduced from magnetic susceptibility and resonance experiments. Two different estimates are made of the mean interaction energy, and these show that about 70% of the total interaction is due to magnetic dipole-dipole coupling. An estimate of the entropy is in excellent agreement with the assumption that the Dy3+ ions may be described in terms of only one Kramers' doublet S′=½.