Observation of pseudo-gap and Kondo behaviour in Al 70Pd 30− xMn x quasicrystals

Abstract

We report here the electrical and magnetic properties of Al 70Pd 30− x Mn x quasicrystals ( x=9 and 11), from resistivity and point contact spectroscopy measurements. Electrical resistivity shows a resistivity maximum for both of these compositions. The positive TCR at lower temperature is attributed to spin–orbit scattering. For x=11, we observe an upturn in the resistivity below 20 K, which follows a ln T dependence indicating Kondo-like behaviour. In the point contact spectroscopy studies we observe two regimes showing a V 2 dependence at low bias voltages (for V<10 meV) crossing over to the V 0.5 dependence at higher voltages. This is attributed to the signature of a pseudo-gap in the density of states at zero bias. We suggest that this V 2 dependence can also arise due to magnetic scattering effects, which are signatures of the Kondo-like behaviour.