UC San Diego

The conditions required for the growths of bulk single crystals of UCoGe and Nd₁.₈₅Ce₀₁₅CuO₄ are reported. Polycrystal samples of the doping series UCo₁-xFexGe were grown and characterized, in particular observing the evolution of ferromagnetism in the series. Low substitutions of Fe increase the ferromagnetic ordering temperature up to 10 K at around 7.5% Fe concentration. Additional substitutions of Fe depresses the ordering temperature until 20% Fe concentration where no magnetic ordering is observed down to 2 K. Ferromagnetic ordering is observed in the high Fe region particularly after annealing at 900⁰C for 240 hours. However, X-ray analysis shows that some impurities formed in this particular region, thus the source of ferromagnetism in this region requires further study