Observation of pseudo-gap and Kondo behaviour in $Al_{70}Pd_{30-x}Mn_x$ quasicrystals

We report here the electrical and magnetic properties of $Al_{70}Pd_{30-x}Mn_x$ 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