Electrical resistivity and point contact studies on Al-Pd-Mn icosahedral quasicrystals

We report measurement of the electrical resistivity rho(T) and point contact differential conductance (dI/dV) for icosahedral Al70Pd30-xMnx (x = 7,9 and 11) at low temperatures. Below 10K, for x = 11, rho(T) follows a log T dependence. All the three compositions show a sharp minimum in the differential conductance near zero bias. Magnitude of the dip in the point contact conductance increases as the Mn concentration increases. The dip near zero bias also follows a log V dependence for V < 30 mV.