FIELD-INDUCED QUENCHING OF THE ENERGY-GAP IN SINGLE-CRYSTAL CENISN

High-field longitudinal magnetoresistance and magnetization measuremen ts up to 36 T have been carried out on a single crystal CeNiSn which s hows metallic behavior in the resistivity along the a-axis. Large nega tive magnetoresistances are found along the a-, b- and c-axes in high fields above 10 T as previously reported in a semiconducting sample. A metamagnetic behaviour in the magnetization is observed along the a-a xis at around 15 T. The linear field dependence of log rho(H) indicate s that the Zeeman energy of the 4f-electron moment quenches the pseudo energy gap on the Fermi surface in CeNiSn.