Electrical transport, magnetic and thermal properties of icosahedral Al-Pd-Mn quasicrystals

Abstract We report measurements of electrical resistivity ( ρ ), Hall coefficient ( R H ) , magnetization ( M ) and specific heat ( C p ( T ) ) of high-quality icosahedral Al 70.4 Pd 20.8 Mn 8.8 phases with different thermal treatment. An improvement in the quasi-crystallinity upon the annealing treatment caused a drastic increase in ρ up to 7000 μΩ cm accompanied by a very small electronic specific heat coefficient γ . The low temperature ρ ( T ) data has been analyzed in terms of weak localization and electron–electron interaction effects. The Hall resistivity ( ρ H ) is found to be strongly temperature-dependent and varies linearly with the magnetization ( M ) for the same field and temperature. Magnetization measurement reveals that more conductive samples are more magnetic and vice versa. Magnetic susceptibility ( χ ) data of all the annealed samples agrees with the Curie–Weiss-like behavior implying the existence of localized moments. The negative Curie–Weiss temperature ( θ ) indicates strong antiferromagnetic coupling between individual Mn atoms. The magnetic Mn concentration is found to be small, ranging from 1.7 3 × 1 0 - 4 for the less magnetic sample studied up to 3 × 1 0 - 3 for the more magnetic one. The small electronic specific heat coefficient obtained for all the samples suggests a significant reduction in the electronic density of states (DOS) at the Fermi level ( E F ) upon thermal annealing treatment.