ANISOTROPIC MAGNETORESISTANCE OF CENISN

We have measured the magnetoresistance at high fields up to 15 T and a t low temperatures down to 0.4 K for CeNiSn with the orthorhombic stru cture. The longitudinal magnetoresistance (J parallel to H) is small i n magnitude for the magnetic field H parallel to b- and c-axis. On the other hand, the positive magnetoresistance is found to become dominan t with the decrease of temperature for H parallel to b- and c-axis in the transverse configuration (J perpendicular to H). For H parallel to a, the magnetoresistance is negative for any current direction. These experimental results have been discussed on the basis of the cyclotro n motion of the compensated carriers with closed Fermi surfaces and th e reduction of the anisotropic hybridization gap.