Title: Magnetic Properties of Stoichiometric NpFe4Al8
Authors: GONCALVES A.p.ALMEIDA M.CARDOSO C.GASCHE T.GODINHO M.BOULET PascalCOLINEAU ERICWASTIN FRANCKREBIZANT JEAN
Citation: JOURNAL OF PHYSICS-CONDENSED MATTER vol. 17 p. 909-922
Publisher: IOP PUBLISHING LTD
Publication Year: 2005
JRC N°: JRC30445
URI: http://publications.jrc.ec.europa.eu/repository/handle/JRC30445
Type: Articles in Journals
Abstract: 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.
JRC Institute:Institute for Transuranium Elements

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