Role of Fe and sign reversal of the Hall coefficient in quasicrystalline Al-Cu-Fe

Abstract

Electronic transport properties were measured for the stable icosahedral phase of Al-Cu-Fe for a large number of high-structural-quality samples of different compositions. At low temperature, the Hall coefficient ${\mathit{R}}_{\mathit{H}}$ and the conductivity \ensuremath{\sigma} are found to best correlate with the Fe content rather than with the electron per atom parameter which is usually used; ${\mathit{R}}_{\mathit{H}}$ changes sign at a concentration of 12.5 at. % Fe, where \ensuremath{\sigma} is at minimum. ${\mathit{R}}_{\mathit{H}}$ has a strong temperature dependence and can change sign with temperature. These features put the focus on the Fe d states and can be interpreted by a Hume-Rothery type of behavior including the sp-d hybridization effects.