Studium magnetických kvantově kritických jevů na uranových sloučeninách

Motivation of this thesis is a study of magnetic phase diagram of the pseu- doternary system UCoxRu1−xAl. Three single crystals UCo0.19Ru0.81Al, UCo0.27Ru0.73Al and UCo0.40Ru0.60Al have been successfully prepared by Czochralski method. Composition was confirmed by EDX analysis and quality of single crystals was checked by Laue method. Crystallographic parameters and occupancies were de- termined by X-ray powder diffraction. Data analysis confirmed strong uniaxial magnetocrystalline anisotropy (c is the easy magnetization axis) and existence of hard and soft ferromagnetic phase. Curie temperature TC = 41 K was determined for UCo0.40Ru0.60Al and phase transition from the soft ferromagnetic phase to the hard one takes place at 35 K. UCo0.27Ru0.73Al becomes ferromagnetic at TC = 18 K and the transition from the soft to the hard ferromagnetic phase takes place somewhere around 7 K. UCo0.19Ru0.81Al is paramagnetic down to 2 K. Analysis of the temperature dependence of resistivity and heat capacity reveals signatures of non-Fermi liquid behaviour due to proximity of quantum critical point.