STUDY OF THE FE-DOPED INTERMETALLIC URANIUM COMPOUNDS

V.V.Sikolenko¹, A.M.Balagurov¹, E.V.Raspopina¹, V.Yu.Pomyakushin¹, I.S.Lyubutin², A.V.Gribanov³

¹Joint Institute for Nuclear Research, 141980 Dubna, Russia, sikolen@nf.jinr.ru
²Institute of Crystallography, Moscow, Russia
³Moscow State University, Russia

Keywords: neutron diffraction, SR method, magnetic structure, intermetallide, spin density wave, spin glass

Most of the uranium intermetallides with the ThCr₂Si₂ type crystal structure exhibit magnetic ordering driven by RKKY-type interaction in competition with a Kondo-type spin compensating mechanism. Some of them demonstrate spin glass like behavior of the magnetic susceptibility.

This report is devoted to review of the magnetic structures of these compounds and, in particular, to UPd₂Ge₂ doped with iron.

Magnetic susceptibility and magnetization studies of the solid solution U(Pd_1-xFe_x)₂Ge₂ showed that magnetic properties are quite different from those of the end-member of the series UPd₂Ge₂ and UPd₂Ge₂. Even a small Fe-doping drastically changes the magnetic state of the compound. In the present systems, a small concentration of Fe impurity in UPd₂Ge₂ enhances the magnetic disorder, which becomes most pronounced at x = 0.02. A ferromagnetic (FM) component was found and a mixed AF-SG-FM phase was observed according to macroscopic data. According to neutron diffraction experiments the magnetic structure of UPd₂Ge₂ is antiferromagnetic (AF) and characterized by a longitudinal spin density wave (LSDW)

In the range of accuracy of the neutron diffraction experiment we could only determine the shape of modulation of magnetic structure (square or sinusoidal), but it was not possible to follow the fluent changes on the form of modulation. Using of SR has been proposed to clarify the details of the magnetic structure of this compound. Another goal of present proposal was to check presence of a mixed AF-SG-FM phase at T < T_N followed from (T) and neutron diffraction measurements. Owing to SR study of the UPd_0.98Fe_0.02Ge₂ it was found that at low temperatures there is AFM magnetic order. The polarization in temperature range of incommensurate LSDW is well described by Bessel function J₀ at the suggestion of presence the only magnetic phase which also proved absence of FM and SG ordering in this compound.