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Highlights: [•] A new uranium intermetallic compound U34Fe4−x ge33 was prepared and characterized. [•] It crystallizes in the tetragonal system with an original structure-type. [•] U lattice stacking is made of cupolae, orthobicupola and irregular cubes. [•] U34Fe4−x Ge33 orders magnetically at TC =28K, with pure U magnetism. [•] TC and electrical resistivity increase with applied magnetic field. [ABSTRACT FROM AUTHOR]

Abstract: Magnetic, thermal, and transport properties of a U3Fe4Ge4 single crystal have been studied. The compound crystallizes in the orthorhombic Gd3Cu4Ge4 structure type. U3Fe4Ge4 displays ferromagnetic order below the Curie temperature T C =18K. The magnetism originates from the uranium sublattice, as iron atoms have no ordered magnetic moments. U3Fe4Ge4 exhibits a pronounced easy-axis anisotropy with the anisotropy field exceeding 60T. The spontaneous magnetic moment is M s =1.2μB/f.u. at T =2K. Magnetic contribution to specific heat shows a gap excitation behavior with Δ =4meV, which can be related to the magnon gap due to the anisotropy. The Sommerfeld coefficient of the electronic specific heat is γ =57mJ/(mol-UK2) in the ordered state, whereas it is much higher (145mJ/(mol-UK2) if derived from the paramagnetic state. Electrical resistivity has very high values on the mΩcm range. [Copyright &y& Elsevier]

Abstract: A new ternary compound, U9Fe7Ge24, was synthesized by arc-melting the elements, followed by annealing at 900 °C. This compound was characterized by single crystal and powder X-ray diffraction, magnetization, specific heat and electrical transport measurements. It crystallizes in an original tetragonal structure type (space group I4/mmm), with lattice parameters a = 12.3789(2) Å and c = 18.2881(3) Å. Three uranium, eighth germanium, and three iron crystallographic sites exist in this structure, with the atoms making a stacking of infinite chains along the a and b axis. From their interatomic distances strong interactions between the uranium and germanium atoms can be predicted. The magnetic and specific heat measurements down to 2 K do not show any magnetic transition. The Curie–Weiss behaviour with a negative paramagnetic Curie temperature θp = −94 K and reduced effective magnetic moment of μ eff = 2.13 μB/U indicate that the compound is rather far from onset of magnetism, presumably due to a strong hybridisation of the 5f and ligand states. The electrical transport measurements show a metallic behaviour. [Copyright &y& Elsevier]

Abstract: The new ternary compound UFe5Ga7 was prepared by an argon arc-melting followed by annealing. This intermetallic compound belongs to the series UFe x Ga12− x and crystallizes in a structure related with the ThMn12-type, with a =8.6309Å and c =5.0524Å. EDS elemental analysis yielded the phase composition UFe4.9(2)Ga6.8(1), which is very close to the nominal composition. Dc magnetization measurements revealed ferromagnetic type of magnetic ordering in UFe5Ga7. The Curie temperature of ∼439K was estimated by the temperature dependence of magnetization at a low magnetic field of 0.1T. [Copyright &y& Elsevier]

Abstract: A new ternary uranium intermetallic compound, U2Fe3Ge, was synthesized and investigated. This compound crystallizes in the MgZn2-type structure ( and , space group ), with uranium–uranium distances well below the Hill limit. Magnetization measurements indicate a ferromagnetic-type transition at 55(1) K. Mössbauer studies show that the magnetic ordering is due only to the uranium sub-lattice, pointing to U2Fe3Ge as a new exception to Hill’s rule. [Copyright &y& Elsevier]

In 3 d − 4 f intermetallic compounds, a Co substitution for Fe usually strengthens the exchange interactions due to a shift of the Fermi energy to a region of the 3 d band with higher density of states. Here, we study the influence of Co on the magnetism of ferrimagnetic DyFe 5 Al 7 using magnetization measurements in static (up to 14 T) and pulsed (up to 58 T) magnetic fields. We find that the homogeneity range of DyFe 5− x Co x Al 7 is limited to x ≤ 2.5 . The Co substitution for Fe produces a strong detrimental effect on the 3 d − 3 d intrasublattice exchange interactions, which leads to a pronounced decrease of the Curie temperature and of the 3 d − 4 f intersublattice exchange field. A reduction of the density of states at the Fermi level might occur due to a broadening of the 3 d band. A decrease of the rare-earth contribution to the magnetic anisotropy energy is also observed with increasing Co content. This is attributed to a competition between the Fe and Co contributions to the crystal electric field at the Dy site. [ABSTRACT FROM AUTHOR]