Thermal expansion of the disordered conductors MNiSn (M=Ti,Zr,Hf).

Abstract

We report on the behavior of the low-temperature transport properties and thermal expansion of the intermetallic compounds MNiSn (M=Ti,Zr,Hf) through the metal-insulator transition. In the low-conductivity samples [\ensuremath{\sigma}\ensuremath{\sim}${10}^{2}$ (\ensuremath{\Omega} cm${)}^{\mathrm{\ensuremath{-}}1}$] situated on the metallic side, the conductivity \ensuremath{\sigma} varies at T10 K as \ensuremath{\sigma}\ensuremath{\approxeq}${\mathrm{\ensuremath{\sigma}}}_{0}$+${\mathit{A}}_{0}$ \ensuremath{\surd}T , which may be ascribed to a Coulomb-interaction correction. For the same temperature interval an anomalous negative thermal expansion with negative values approximately proportional to the degree of interaction, evaluated from the conductivity, was observed. A discussion of the possible effect of electron-electron interaction on the electron thermal expansion based on the results of Altshuler and Aronov is also presented.