Impurity-induced localization of quasiparticles in the presence of a pseudogap in CeNiSn

The effect of doping in CeNiSn has been studied by the measurements of elec trical resistivity, Hall coefficient and magnetic susceptibility for single crystals of CeNi1-xTxSn (T = Co, Cu, and Pt) and Ce1-yLayNiSn (x,y = 0.01 and 0.05). All these impurities are found to increase the residual resistiv ity by several times up to 1 m Omega cm for x or y = 0.01, while for x or y = 0.05 the resistivities along the orthorhombic b and c axes saturate to v alues smaller than those for 0.01. Further, the low-temperature increase in the Hall mobility of CeNiSn was found to be strongly suppressed in a simil ar way by all the impurities. These results indicate that residual carriers in CeNiSn with an anisotropic gap are immobilized by any impurity substitu ted either in the 4f site or the non-4f site. [S0163-1829(99)04121-1].