Magnetic susceptibility of californium fluorides

Results of magnetic measurements are presented for polycrystalline samples of CfF3 (both the hexagonal-LaF3-type and orthorhombic-YF3-type crystal structures) and CfF4 (monoclinic-UF4-type). Measurements were performed at temperatures between 4.2 and 340 K and in magnetic fields of up to 50 kG. The effective paramagnetic moments, μeff, and the Weiss constants, FTHETAP, have been determined in the Curie-Weiss temperature region (150–340 K). In the trifluorides no significant differences in μeff and FTHETAP were observed as a function of crystal structure or sample age (radiation damage). For the tetrafluoride, two distinct sets of values for μeff and FTHETAP were obtained depending on the sample age. Antiferromagnetic ordering was observed in both Cf compounds at temperatures below 12 K. Crystal-field effects were evident in the temperature range between about 12 and 150 K. The calculated susceptibilities for these compounds are presented and discussed.