A combination of ac susceptibility, dc magnetization in a variety of applied fields, and electrical resistivity data is reported for five members of the R2Mo2O7 series of cubic pyrochlore structure oxides, R = Nd, Sm, Gd, Tb, and Y. These measurements extend published studies on the compounds and aid in the clarification and interpretation of the magnetic and electrical transport properties. The metallic ferromagnetics, R = Nd, Sm, and Gd, order at 96, 80, and 57 K, respectively. For R = Nd and Sm this is due most likely to ordering of Mo(IV) moments of about 1 μB. Near 30 K both compounds show hysteresis in the dc magnetization due to complex RMo coupling which give rise to resistivity minimum. For Gd2Mo2O7 there is no low temperature hysteresis, indicating that both sublattices order ferromagnetically at the same temperature. A magnetization anomaly in semiconducting Tb2Mo2O7 at 25 K which is attributed to long range or short range magnetic order is reported for the first time and ac susceptibility data confirm a spin-glass like transition in Y2Mo2O7 reported previously. A correlation between the cubic lattice constant and the electrical and magnetic properties is noted.
