Magnetothermodynamics of gadolinium gallium garnet. III. Heat capacity, entropy, magnetic moment from 0.5 to 4.2thinsp;deg;K, with fields to 90 kG along the lsqb;110rsqb; axis

摘要

The magnetic moment of a 2.44 cm diam spherical single crystal of gadolinium gallium garnet has been measured with stabilized fields of 500, 1000, 2500, 5000, 10thinsp;000, 12thinsp;500, 15thinsp;000, 20thinsp;000, 25thinsp;000, 40thinsp;000, 65thinsp;000, and 90thinsp;000 G along the lsqb;110rsqb; crystal axis, over the range 0.5 to 4.2thinsp;deg;K. The magnetic moment reached saturation at 90 kG and 0.35thinsp;deg;K. The heat capacity was measured over the 0.5ndash;4.2thinsp;deg;K temperature range and the above fields except that 500 and 1000 G were omitted and zero field included. The zero of electronic and lattice entropy was located at 90 kG and magnetic saturation. Temperatures were measured versus field on 36 adiabatics, corrected with respect to entropy. These provided multiple intersections with the isoerstedic heat capacity curves, so that the entropy could be evaluated over the entire temperature and field ranges of the investigation. The saturation moment was found to be Mlsqb;110rsqb;= 38thinsp;963 Gsdot;cm3/mole Gd3+, equivalent toglsqb;110rsqb;= 1.993. This may be compared with the previous similar measurements Mlsqb;100rsqb;= 39thinsp;059 and Mlsqb;111rsqb;= 38thinsp;979 Gsdot;cm3/mole Gd3+, corresponding toglsqb;100rsqb;= 1.998 andglsqb;111rsqb;= 1.994. Smoothed correlated values of the heat capacity, entropy, enthalpy, internal energy, magnetic moment and its differential isoerstedic temperature coefficient, differential isothermal magnetic susceptibility, and the isothermal work of magnetization, have been tabulated over the ranges 0ndash;90 kG and 0.5ndash;4.2thinsp;deg;K.