Anomalous Angular Dependence of Magnetoresistance in MCl2-GIC's (M=Cu and Co)

Abstract

Angular dependence of the c-axis magnetoresistance of stage-1 and stage-2 MCI2 GIC (M=Cu and Co) was measured. Stage-1 CuCl2 GIC shows an angular dependent magnetore-sistance oscillation (ADMRO) characteristic in the systems having a periodically-warped cylindrical Fermi surface (FS). This means that the conduction along the c-axis is band-like in spite of extremely large anisotropy in conductivity. On the other hand, the angular dependence of the magnetoresistance of stage-2 CuCl2 GIC and stage-1 CoCl2 GIC can be interpreted as the mixture of ADMRO based on a band conduction and incoherent interlayer hopping. Stage-2 CoCl2 GIC shows only incoherent hopping. In low magnetic field region, the c-axis resistances of stage-1 and stage-2 CoCl2 GIC are affected by the magnetic phase transitions. Spin-dependent tunneling effect can explain this phenomenon.