Negative Longitudinal Magnetoresistance in the c-Axis Resistivity of Cd^*

We report a systematic study on magnetotransport properties of the single crystal of cadmium (Cd). When the applied magnetic field B is perpendicular to the current I, the resistivities for both directions (I || a, I || c) show field induced metal-to-insulator-like transitions. The isothermal magnetoresistance (MR) at low temperatures increases approximately as the square of the magnetic field without any sign of saturation, and reaches up to 1140000% and 58000% at T = 2 K and B = 9 T for I || a and I || c, respectively. As the magnetic field rotates to parallel to the current, no sign of negative MR is observed for I || a, while an obvious negative MR appears up to −70% at 2 K and 9 T for the current flowing along the c-axis, and the negative longitudinal MR shows a strong dependence of the electrode position on the single crystal. These results suggest that the negative longitudinal MR is caused by the dislocations formed in the process of crystal growing along the c-axis. Further studies are needed to clarify this point. (paper)