Scopul nostru este sprijinirea şi promovarea cercetării ştiinţifice şi facilitarea comunicării între cercetătorii români din întreaga lume.
Autori: A. Galatanu, Y. Haga ,T.D. matsuda, S. Ikeda, E. Yamamoto, D. Aoki, T. Takeuchi and Y. Onuki
Editorial: The Physical Society of Japan, Journal of the Physical Society of Japan, 74 (5), p.1582-1597, 2005.
We investigated the magnetic properties of typical uranium compounds by measuring the magnetic
susceptibility in an extended temperature range up to about 800 K. The magnetic susceptibility follows
the Curie –Weiss law for a localized 5f2-electron compound UPd3 and a ferromagnetic insulator UFe4P12 .
In most of the investigated compounds we observed a crossover effect of the 5 f electrons from a low-
temperature itinerant nature to a high-temperature localized one. This is found to be characteristic for
ferromagnetic superconductors such as UGe2 and UIr,and also for antiferromagnets like USb2 or
UNiSb2. To assess an extension of this characteristic property in the uranium compounds we also
investigated typical 5f -itinerant compounds like UGa3 and UPtGa5 .The crossover effect is essentially
important in heavy fermion compounds such as UPt3 ,UPd2Al3 and URu2Si2. Even in the paramagnetic
compound of UB4, the magnetic susceptibility is not temperature-independent, but approaches a 5f –
localized tendency at high temperatures. Since the samples were single crystals, we were also able to
trace the evolution of the magnetic anisotropy. The high-temperature anisotropic susceptibility data were
analyzed on the basis of the crystalline electric ﬁeld scheme.
Cuvinte cheie: magnetism, 5f configurations, heavy fermions