Magnetic and Electronic Properties of Cubic NpX sub 3 Intermetallics

• Published in: Physical review. B, Condensed matter Vol. 46; no. 9; pp. 5351 - 5356
• Main Authors: Gal, J, Yaar, I, Fredo, S, Halevy, I, Potzel, W, Zwirner, S, Kalvius, G M
• Format: Journal Article
• Language: English
• Published: 01-09-1992
• ISSN: 0163-1829

The magnetic and electronic properties of NpSi sub 3 , NpGa sub 3 , and NpIn sub 3 , which crystallize in the cubic AuCu sub 3 crystallographic structure (space group Pm3m), are reported. Studies by Mossbauer as well as ac and dc magnetization techniques are presented. From the Mossbauer isomer-shift data it is argued that the Np ion in NpX sub 3 is close to the formal 3+ ( exp 5 I sub 4 ) charge state. The magnetic moment of the Np in NpSi sub 3 is totally suppressed, whereas in NpGa sub 3 a localized (narrow band) moment (1.5 mu sub B ) is established. However, in NpIn sub 3 at 4K, a modulated magnetic moment [(0-1.5) mu sub B ] is observed. Comparing the magnetic behavior of the NpX sub 3 family (X = Si, Al, Ga, Ge, Sn, and In), an impressive variation of the magnetic properties, from temperature-independent paramagnetism, localized and modulated ordered moments, to the formation of a concentrated Kondo lattice, is found. Hybridization of 5f electrons with ligand electrons appears to play a crucial role in establishing these magnetic properties. However, a consistent theoretical picture cannot be drawn at present.