| |
Abstract |
Low-temperature thermal (specific heat, C-P) and magnetic [ac susceptibility, chi(ac), and isothermal magnetization M(B)] measurements on CeTyX4-y ferromagnets (with T = Ni, Cu, Pd, Ag, Au, and X = Ga, Al, with 0.3 < y < 0.7) are reported. With the exception of T = Ni, all compounds with X = Ga show a typical second-order ferromagnetic transition. In the case of T = Ni, magnetic correlations set in at T approximate to 3T(C), (T-C being the Curie temperature) and the C-P(T) and chi(ac)(T) maxima (at 3.3 and 4.2 K, respectively) do not coincide, while the M(B) curves reveal an antiferromagnetic character at lower temperatures. In these systems, the magnetic entropy of the ordered phase is larger than 85% of Rln2, in coincidence with the low values of the Sommerfeld coefficient gamma less than or equal to 10 mJ/mol K-2. For T = Ag and X = Al, a strong diamagnetic signal was observed at T-s = 0.63 K in chi(ac)(T), with the characteristics of a superconducting component. The thermodynamical properties of these compounds confirm the lack of hybridization when the Ce atom is in a ferromagnetic ground state. |
|
