Magnetic phase transition in Ti-doped ErCo2 alloys

The influence of the non-magnetic Ti substitution for the Co atoms on the electronic structure and the magnetic state of the ErCo2 compound has been investigated by means of electrical resistivity and magnetization measurements. Arc-melted Ti-doped ErCo2 samples, ErCo2-xTix (x=0, 0.04, 0.05, 0.07, 0.10, and 0.20) are crystalized with the same cubic Laves phase C15 (space group Fd3-barm) at room temperature. The crystal parameter a increases almost linearly with increasing Ti content up to x=0.20. In connection with the first-order magnetic phase transition, a sharp drop in the resistivity and a rapid increase in the magnetization are observed in all samples at a transition temperature, Tc. The transition temperature slightly decreases at first and then increases gradually with higher concentrations of Ti contents. The overall resistivity of these compounds in the temperature range of 4-300 K increases considerably, but decreases rapidly with decreasing temperature as the Ti concentration is increased. Resistivity data have been analyzed using the existing model in the literature. In addition, magnetization versus temperature curves for both zero-field cooled (ZFC) and field-cooled case (FC) in the measuring field of 50 Oe were recorded. First-order like jump in magnetization and splitting of ZFC and FC curves (irreversibility effects set in) at Tc are observed for all samples. The most striking features are: FC magnetization below Tc reduces gradually but significantly and coercivity inferred from the hysteresis cycles at T=4.2 K increases with Ti concentration