Magnetothermodynamics of Antiferromagnetic, Ferroelectric β-Gd2(MoO4)3. III. Heat Capacity, Entropy, Magnetic Moment of the Electrically Polarized Form from 0.4 to 4.2°K with Fields to 90 kG along the b Crystal Axis

Abstract

The magnetic moment of a 2.49 cm diam spherical single crystal of electrically polarized β‐Gd₂(MoO₄)₃ has been measured with fields of 500, 1000, 1500, 2500, 5000, 10 000, 15 000, 25 000, 40 000, 65 000, and 90 000 G, along the b crystal axis, and over the range 0.3–4.2°K. The approach to saturation was measured at about 0.45°K over the range 35 to 90 kG. The temperature independent susceptibility along the b axis (diamagnetic) was determined as ${\text{−3.6× 10}}^{\text{−4}}\hspace{0.17em}{\mathrm{cm}}^3/{\mathrm{mole\; Gd}}^{\text{3+}}$ and the limiting saturation value was found to be $\text{38\hspace{0.17em}805\hspace{0.17em}}\mathrm{G}·{\mathrm{cm}}^3/\mathrm{mole}\hspace{0.17em}{\mathrm{Gd}}^{\text{3+}}$ , corresponding to $g_b{\text{=1.985=g}}_a{\mathrm{=g}}_c$ . The heat capacity has been measured in fields of 0, 1000, 2500, 5000, 10 000, 15 000, 25 000, 40 000, 65 000, and 90 000 G over a range from 0.4 to 4.2°K. The heat of vaporization of momentum, h/2π, from the essentially saturated state, was found to be 23.10 and 16.48 cal/mole of h/2π at 90 and 65 kG, respectively. This may be compared with the work of this process, g_bβH, which is 23.85 and 17.22 cal/mole of h/2π at these two respective fields. Temperature‐field observations on thirty‐one isentropes were used to correlate the entropies along the ten isoerstedic heat capacity series. The zero of entropy of the electronic and lattice systems was located at magnetic saturation by means of the heat capacity series at 90 and 65 kG. Smoothed correlated values of the heat capacity, entropy, enthalpy, internal energy, magnetic moment and its isoerstedic temperature coefficient, the differential magnetic susceptibility, and the isothermal work of magnetization, have been tabulated over the range 0–90 kG and 0.4–4.2°K.