Electronic transport of the icosahedral Zn-Mg-Sc quasicrystal and its cubic approximantZn17Sc3

Abstract

The electrical resistivity and specific-heat measurements have been performed for the recently discovered P-type icosahedral Zn-Mg-Sc of high structural perfection and its crystalline approximant ${\mathrm{Zn}}_{17}{\mathrm{Sc}}_{3}.$ The temperature coefficient of the resistivity is found to be negative with ${\ensuremath{\rho}}_{300K}=330\ensuremath{\mu}\ensuremath{\Omega}\mathrm{cm}$ for the quasicrystal, while it is positive with ${\ensuremath{\rho}}_{300K}=250\ensuremath{\mu}\ensuremath{\Omega}\mathrm{cm}$ for the crystalline approximant. The electronic specific-heat coefficient $\ensuremath{\gamma}$ is found to be small and nearly the same for both alloys; 0.55 and $0.65\mathrm{mJ}/(\mathrm{mole}{\mathrm{K}}^{2})$ for the quasicrystal and the crystalline approximant, respectively. Such small $\ensuremath{\gamma}$ values are consistent with the recent electronic structure calculation [Ishii and Fujiwara, J. Alloys. Compd. 342, 343 (2002)], and can be taken as an indication of the existence of a pseudogap in the density of states at the Fermi level for the P-type i phase.