Anomalous scattering of quasiparticles by Co and Cu impurities in the Kondo semimetal CeNiSn

Abstract We present results of the magnetic susceptibility χ ( T ), electrical resistivity ϱ ( T ) and Hall coefficient R H ( T ) for CeNi 1− x T x Sn (T  Co and Cu, 0 ⩽ x ⩽ 0.05). Co impurities decrease χ along all the principal axes, whereas Cu impurities increase. Both impurities at x = 0.01 cause a remarkable increase in ϱ at 1.4 K with 970 μΩcm/at%Cu at maximum. For x = 0.05, ϱ ( T ) is saturated to a lower value than that for x = 0.01. R H ( T ) for x = 0.01 Co and Cu becomes negative below about 4 K and the absolute value is smaller than that for x = 0, while R H for x = 0.05 remains positive down to 1.6 K. The nonmonotonic dependence of ϱ ( T ) and R H ( T ) on x indicates extremely strong scattering of quasiparticles from nonmagnetic impurities in the presence of pseudogap.