We report on single crystal growth and crystallographic parameters results of Ce 2 PdIn 8 , Ce 3 PdIn 11, Ce 2 PtIn 8 and Ce 3 PtIn 11 . The Pt-systems Ce 2 PtIn 8 and Ce 3 PtIn 11 are synthesized for the first time. All these compounds are member of the Ce n T m In 3n+2m (n = 1, 2,..; m = 1, 2,.. and T = transition metal) to which the extensively studied heavy fermion superconductor CeCoIn 5 belongs. Single crystals have been grown by In self-flux method. Differential scanning calorimetry studies were used to derive optimal growth conditions. Evidently, the maximum growth conditions for these materials should not exceed 750 °C. Single crystal x-ray data show that Ce 2 TIn 8 compounds crystallize in the tetragonal Ho 2 CoGa 8 phase (space group P4/mmm) with lattice parameters a =4.6898(3) Å and c =12.1490(8) Å for the Pt-based one (Pd: a = 4.6881(4) Å and c = 12.2031(8) Å). The Ce 3 TIn 11 compounds adopt the Ce 3 PdIn 11 structure with a = 4.6874(4) Å and c = 16.8422(12) Å for the Pt-based one (Pd: a = 4.6896 Å and c = 16.891 Å). Specific heat experiments on Ce 3 PtIn 11 and Ce 3 PdIn 11 have revealed that both compounds undergo two successive magnetic transitions at T 1 ~ 2.2 K followed by T N ~ 2.0 K and T 1 ~ 1.7 K and T N ~ 1.5 K, respectively. Additionally, both compounds exhibit enhanced Sommerfeld coefficients yielding γ Pt = 0.300 J/mol K 2 Ce (γ Pd = 0.290 J/mol K 2 Ce), hence qualifying them as heavy fermion materials.

Pure hydride of the α-UH type without any β-UH admixture was prepared by high-pressure hydrogenation of U stabilized by Zr. Such material, characterized by a general formula (UH) Zr , is stable in air at ambient and elevated temperatures. H release is observed between 400-450 °C similar to β-UH. Its stability allowed to measure magnetic properties, specific heat, and electrical resistivity in a wide temperature range. Despite rather different crystal structure and inter-U spacing, the electronic properties are almost identical to β-UH. Its ferromagnetic ground state with Curie temperature ≈ 180 K (weakly and non-monotonously dependent on Zr concentration) and U moments of 1.0 μ indicate why mixtures of α- and β-UH exhibited only one transition. Magnetic ordering leads to a large spontaneous magnetostriction = 3.210, which can be explained by the increase of the spin moment between the paramagnetic (Disordered Local Moment) and the ferromagnetic state. The role of orbital moments in magnetism is indicated by fully relativistic electronic structure calculations.

The effect of Cu substitution on the stability of the CuMnAs tetragonal phase was studied both experimentally and by ab initio calculations. Polycrystalline samples with various compositions Cu1+xMn1-xAs (x = 0-0.5) were synthetized. The tetragonal phase of CuMnAs is found to be stabilized by substituting Mn by Cu in the amount of x ~ 0.1 or higher. This observation is supported by ab initio calculations of the total energy of the tetragonal and orthorhombic phases; with increasing Cu content the tetragonal phase is favoured. Small variations of composition thus allow to grow selectively one of these two phases with distinct and unique features for antiferromagnetic spintronics.Measurements of magnetic susceptibility and differential scanning calorimetry have shown that the tetragonal Cu1+xMn1-xAs has an antiferromagnetic behaviour with the maximum Néel temperature TN = 507 K for the highest Mn content samples, decreasing with the decreasing Mn content.

No abstract

UH 3 is the first discovered material with ferromagnetism based purely on the 5f electronic states, known for more than half century. Although the U metal is Pauli paramagnet, the reduced 5f-5f overlap in compounds allows for moment formation and ordering, typically if the U-U spacing exceeds the Hill limit, i.e. about 340 pm. The stable form of UH 3 , known as β-UH 3 , has rather high T C ≈ 170 K. Such high value is rather unusual, considering d U-U = 331 pm. Properties of metastable α-UH 3 with d U-U = 360 pm could be never well established. Using the fact that α-UH 3 is in fact bcc U with interstitials filled by H, we attempted to synthesize α-UH 3 starting from the γ-U alloys, with the bcc structure retained to room temperature by doping combined with ultrafast cooling. While up to 15% Zr a contamination by β-UH 3 was obtained, 20% Zr yielded single phase α-UH 3 . The T C value remains high and very similar to β-UH 3 . One can see an increase up to 187 K for 15% Zr, followed by a weak decrease. Magnetic moments remain close to 1 μ B /U atom. An insight is provided by ab-initio calculations, revealing a a charge transfer towards H-1s states, depopulating the U-6d and 7s states, leaving almost pure 5f character around the Fermi level. The 5f magnetism exhibits a high coercivity (μ 0 H c up to 5.5 T) and large spontaneous volume magnetostriction of 3.2*10 -3 . Even higher increase of T C , reaching up to 203 K, can be achieved in analogous Mo stabilized hydrides, which yield an amorphous structure. The compounds represent, together with known hydrides of U 6 Fe and U 6 Co, a new group of robust 5f ferromagnets with small d U-U but high T C . Although common hydrides are fine powders, some of the new hydrides described as (UH 3 ) (1-x) T x (T = Zr or Mo) remain monolithic, which allows to study transport and thermodynamic properties.