Magnetic Properties of Stoichiometric NpFe4Al8

The compound NpFe4Al8 was prepared by direct arc melting of the constituent elements, followed by annealing. It crystallizes in the ThMn12-type structure (space group I4/mmm, a = 8.7480(5) A, c = 5.0372(4) A), with the iron atoms completely and only occupying the 8f positions. Magnetization measurements (T = 2–300 K, B = 0–7 T) show a ferromagnetic-type transition at TC = 135(2) K and a second anomaly at 118(3) K. The low temperature magnetization cycle is characterized by a hysteresis with a step similar to that previously observed forUFe4Al8 single crystals. First-principles density functional theory calculations of the NpFe4Al8 band structure point to a magnetic structure similar to that of UFe4Al8, in agreement with the observed magnetization cycle. The calculations indicate that the neptunium moment is aligned along one of the a or b axes, and the iron moments form a noncollinear structure in the a–b plane, with the antiferromagnetic and ferromagnetic contributions perpendicular and antiparallel to the neptunium spin moment, respectively.

GONCALVES A.P.;  ALMEIDA M.;  CARDOSO C.;  GASCHE T.;  GODINHO M.;  BOULET Pascal;  COLINEAU Eric;  WASTIN Franck;  REBIZANT Jean; 

2005-09-12

IOP PUBLISHING LTD

JRC30445

https://publications.jrc.ec.europa.eu/repository/handle/JRC30445,   

10.1088/0953-8984/17/6/010,