Formation of an anisotropic energy gap in the valence-fluctuating system of CeNiSn

摘要: Measurements of susceptibility \ensuremath{\chi}, resistivity \ensuremath{\rho}, and thermoelectric power S have been performed on single-crystal CeNiSn. Only along the a axis orthorhombic structure do \ensuremath{\chi}(T) \ensuremath{\rho}(T) exhibit pronounced peaks at 12 K, whereas no anomaly was found in specific heat. The gap energies estimated from are 2.4, 5.5, 5.0 K a, b, c axes, respectively. Near 3 ${\mathit{S}}_{\mathit{a}}$(T) ${\mathit{S}}_{\mathit{c}}$(T) extremely sharp peaks, which indicate presence density states within gap. magnetic contribution to heat divided by temperature, ${\mathit{C}}_{\mathit{m}}$/T versus T reveals maximum 0.19 J/${\mathrm{K}}^{2}$ mol near 6.7 K. These results suggest that an antiferromagnetic correlation develops induces formation pseudogap narrow band heavy quasiparticles.