Magnetization and magnetic entropy of Dy2Ti2O7

Isothermal measurements of the magnetic entropy, magnetization, and differential susceptibility of Dy2Ti2O7 have been made. Absolute values of magnetic entropy have been determined as a function of applied magnetic field for several temperatures in the range 2–20 K, and several isofield lines in the magnetic entropy-temperature plane have been determined. Magnetization measurements, which extended into the saturation region, yield a powder-average magnetic moment of 4.7±0.2 μB/ion. A van Vleck contribution to M was also observed. The results are consistent with the assumption of a nearly pure Jz = ± 15/2 ground-state Kramers doublet for the Dy+++ ion. Comments on the suitability of Dy2Ti2O7 for use in a magnetic refrigerator cycling between 4.2 and 20 K are included.