Determination of the Entropy via Measurement of the Magnetization: Application to the Spin ice Dy2Ti2O7

Abstract

The residual entropy of spin ice and other frustrated magnets is a property of considerable interest, yet the usual way of determining it, by integrating the heat capacity, is generally ambiguous. Here we note that a straightforward alternative method based on Maxwell's thermodynamic relations can yield the residual entropy on an absolute scale. The method utilises magnetization measurements only and hence is a useful alternative to calorimetry. We confirm that it works for spin ice, Dy2Ti2O7, which recommends its application to other systems. The analysis described here also gives an insight into the dependence of entropy on magnetic moment, which plays an important role in the theory of magnetic monopoles in spin ice. Finally, we present evidence of a field-induced crossover from correlated spin ice behaviour to ordinary paramagnetic behaviour with increasing applied field, as signalled by a change in the effective Curie constant.

10 pages, 5 figures. Manuscript submitted. second version, few minor errors amended

References in corpus (5)

• Theory of the [111] magnetization plateau in spin ice
• Dy2Ti2O7 Spin Ice: a Test Case for Emergent Clusters in a Frustrated Magnet
• Topological Sector Fluctuations and Curie Law Crossover in Spin Ice
• Crystal Shape-Dependent Magnetic Susceptibility and Curie Law Crossover in the Spin Ices Dy2Ti2O7 and Ho2Ti2O7
• High temperature onset of field-induced transitions in the spin-ice compound Dy2Ti2O7