Crystal structure and physical properties of a novel Kondo antiferromagnet: U₃Ru₄Al₁₂

Abstract

A novel ternary compound U(3)Ru(4)Al(12) has been identified in the U-Ru-Al ternary diagram. Single-crystal x-ray diffraction indicates a hexagonal Gd(3)Ru(4)Al(12)-type structure for this uranium-based intermetallic. While this structure type usually induces geometrically a spin-glass behaviour, an antiferromagnetic ordering is observed at T(N) = 8.4 K in the present case. The reduced effective magnetic moment of U atoms (μ(eff) = 2.6 µ(B)) can be explained by Kondo-like interactions and crystal field effects that have been identified by a logarithmic temperature dependence of the electrical resistivity, negative values of the magnetoresistivity and particular shape of the Seebeck coefficient.

Crystal structure and physical properties of a new intermetallic compound URu2Al10

“…The value of an effective uranium moment is higher than those determined in UAl 2 (m eff ¼ 2.92 m B [24] or in other ternary UeRueAl aluminides (m eff ¼ 2.0 and 2.6 m B for URuAl [1,2] and U 3 Ru 4 Al 12 [3], respectively). In turn, as the inset to this figure illustrates, above about 100 K a CurieeWeiss behaviour is well followed with m eff ¼ 3.26 m B and fairly large negative paramagnetic Weiss temperature q p z À169 K [see the inset to Fig.…”

“…Up to now, in literature, only two ternary phases have been reported in the UeRueAl system, namely the spin-fluctuator URuAl [1,2] and the antiferromagnet U 3 Ru 4 Al 12 [3] with the hexagonal ZrNiAl and Gd 3 Ru 4Àx Al 12þx types of structure, respectively. However, further investigation of this phase diagram reveals the existence of a novel phase in the Al-rich corner, namely URu 2 Al 10 , crystallizing in the orthorhombic YbFe 2 Al 10 structure-type [4].…”

The isothermal section of the La–Ag–Mg phase diagram at 400 °C

“…The reflections conditions analysis (h þ k þ l ¼ 2n) of the corresponding X-ray Table 3 Selected crystallographic data and structure refinement parameters for La 2-0.18 Mg 17þ0. 35 (4) Dr fin (max/min), e  10 À3 /nm 3 1.06 and À0.68 2.22 and À2.42…”

Magnetocaloric properties of a novel ferromagnet Gd3Co4+xAl12−x (x = 0.50)

“…1 from Ref. [7] for a detailed description of this structure) where they are connected into small [Gd 3 ] triangles where d Gd-Gd ¼ 3.64 Å, i.e. close to the sum or metallic radii, connecting each other in larger [Gd 3 ] triangles where d Gd-Gd ¼ 5.04 Å, i.e.…”

“…The spin glass behavior observed in U 3 T 4þx Al 12Àx for T ¼ Fe (x ¼ 0) [5] and Co (x ¼ 0.55) [6,8] was attributed to these crystallographic features. Opposite, the ruthenium based phase (x ¼ 0) was found to order antiferromagnetically at T N,poly ¼ 8.4 K [7]. A single crystal investigation of U 3 Ru 4 Al 12 including neutron diffraction indicated an original ordering of the magnetic moments carried by uranium atoms, within the kagom e network, i.e.…”