Abstract
Mössbauer effect and neutron diffraction studies on the tetragonal NpM4Al8−x (M=Cr, Fe, Cu) of the 14/mmm space group are reported. In NpFe4Al8−x, both the Np and Fe sites order magnetically at close temperatures: the Np order ferromagnetically at 115(15) K (μ(Np)) ∼ 0.6 μB and the Fe moments order antiferromagnetically at 130(10) K (μ(Fe) = 1.05(15) μB) with a ++−− sequence. In NpCr4Al8−x, the Np order magnetically around 50K. From the susceptibility data we conclude possible antiferromagnetic order of both Np and Cr sites. NpCu4Al8−x does not order magnetically down to at least 2 K. The magnetic hyperfine splitting observed below 45 K is explained by slow paramagnetic relaxation. The Np isomer shifts and also its magnetic behavior point to a trivalent ion (5I4 Hund's rule ground state). The observed relaxation and magnetic phenomena are discussed in terms of crystalline electric field effects. In contrast to the isostructural rare-earth RM4Al8 compounds with practically independent order of R and M magnetic sublattices, we show that Np and M sublattices in NpM4Al8 are strongly coupled. This is caused by hybridization of both Np and M atoms with Al.
Similar content being viewed by others
References
M.O. Bargouth, G. Will and K.H.J. Buschow, J. Magn. Magn. Mater. 6(1977)129.
I. Felner and I. Nowik, J. Phys. Chem. Solids. 39(1978)951.
K.H.J. Buschow and A.M. van der Kraan, J. Phys. F5(1978)921.
W. Schäfer and G. Will, J. Less Common Met. 94(1983)205.
A. Baran, W. Suski and T. Mydlarz, Physica 130B(1985)219.
J. Gal, H. Pinto, S. Fredo, M. Melamud, H. Shaked, R. Caciuffo, F.J. Litterst, L. Asch, W. Potzel and G.M. Shtrikman, Rev. Sci. Inst. 51(1980)L123.
P.J. Flanders and S. Shtrikman, Rev. Sci. Inst., 51(1980)5.
B.D. Dunlap and G.H. Lander, Phys. Rev. Lett. 33(1974)1046.
A.J. Freeman and R.E. Watson, in:Magnetism, Vol. IIa (Academic Press, New York, 1964) p. 167 ff.
I. Felner, I. Nowik and M. Seh, J. Magn. Magn. Mater. 38(1983)172.
Author information
Authors and Affiliations
Additional information
Work supported by the Bundesministerium für Forschung und Technologie, FRG, and the National Council of Research and Development (NCRD), Israel.
Rights and permissions
About this article
Cite this article
Gal, J., Pinto, H., Fredo, S. et al. Magnetic properties of NpM4Al8−x (M=Cr, Fe, Cu) intermetallics: Mössbauer effect and neutron diffraction studies. Hyperfine Interact 33, 173–190 (1987). https://doi.org/10.1007/BF02394107
Issue Date:
DOI: https://doi.org/10.1007/BF02394107