Applications of Miniature Coil, Pulsed-Field Techniques to Studies of Magnetic Phase Transitions

Abstract

A miniature coil, pulsed‐field technique is described in which magnetic fields above 100 kOe can be easily obtained in 20‐ to 40‐μsec pulse lengths. Detailed description is given of the apparatus. The use of such pulsed fields in study of antiferromagnetic‐ferrimagnetic transitions in Mn_1.90Cr_0.10Sb is described. The transition latent heat in Mn_1.90Cr_0.10Sb is found to be 0.35 cal/mole°C from these measurements. Critical fields for ferromagnetic‐antiferromagnetic transitions in holmium and dysprosium are determined with this technique. The transition entropy change in dysprosium is found to be 2.59×10⁴ ergs/g°C. Spin flopping is observed in Mn_1.84Cr_0.16Sb between 20° and 85°C. The anisotropy field of the canted spin state in Mn_1.84Cr_0.16Sb is found to be of the order of 10³ Oe. Pulsed field measurements of ferromagnetic‐paramagnetic transitions are discussed. It is shown how this technique can be used to determine Curie temperatures of such transitions. Curie temperatures of 16° and 118°C are found, respectively, for gadolinium and CrO₂.