Anomalous magnetotransport properties of R2Mo2O7 near the magnetic phase boundary

The magnetic and transport properties of pyrochlore R2Mo2O7 have been studi ed with variation of the rare earth (R). The change of the mean ionic radiu s of R, which induces change of the lattice structure, determines the magne tic ground state (ferromagnetic or spin glass), and the magnetic phase boun dary is correlated with the metal-insulator crossover. Furthermore, we foun d enhanced magnetoresistance and unusual residual anomalous Hall effect at low temperatures near the phase boundary, which can be attributed to the co existence of both phases.