Abstract
We have measured the longitudinal magnetoresistance ρ zz of graphite in high magnetic fields of up to -- 37, T at low temperatures down to -- 0.6, K. A dramatic increase in ρ zz was newly found in the high-field-low-temperature region. We have also found prominent non-ohmicity in the current-voltage characteristic in ρ zz over the relevant magnetic-field-temperature region. This non-ohmic behavior is reminiscent of sliding motion of a pinned charge-density wave or spin-density wave, the direction of which is mainly parallel to the c-axis. This magnetoresistance anomaly could be attributed to a magnetic-field-induced 2kF-type instability due to the one-dimensionality caused by Landau quantization.
