Magnetic and electrical transport properties of the pyrochlore iridate Bi2-xCoxIr2O7

In the present paper, we have studied the magnetic order and electrical transport properties of frustrated magnet Bi2-xCoxIr2O7 (x  =  0, 0.2, 0.4, 0.6) polycrystalline. The behavior of the electrical resistivity above 50 K in the composites emanate from the electron-electron scattering processes. Grain boundary effects play a dominant role in the conduction process. It is also found from M-T data that the antiferromagnetic interaction and frustration enhances with increasing content of Co. Effective magnetic moments show a possibility of mixed valence state of Co (Co3+ and Co4+). The M-H data of doped samples taken at 2 K show hysteresis loops, which suggests the existence of ferromagnetic interaction originated from canted antiferromagnetic state. The magnetic behavior results from the competition between ferromagnetic and antiferromagnetic interaction at each magnetic site.