Magnetic and electrical properties of a Cu–Ga–Mg–Sc icosahedral quasicrystal

We have investigated the magnetic susceptibility and the electrical resistivity of a new P-type icosahedral quasicrystal Cu 48.2 Ga 33.8 Mg 3 Sc 15 and a cubic phase Cu 49 Ga 36 Sc 15 , interpreted as a 1/1 approximant crystal of the quasicrystal. The magnetic susceptibility of the Cu 48.2 Ga 33.8 Mg 3 Sc 15 quasicrystal showed an increase from -3.51 x 10 -4 to -2.78 × 10 4 m 3 kg 1 with a rise in temperature from 120 to 300 K. The Cu 49 Ga 36 Sc 15 cubic phase showed also a rise from -6.18 × 10 -4 to -4.50 × 10 -4 m 3 kg -1 between 100 and 300 K. The increase in the susceptibility was accounted for by the temperature dependence of the Pauli paramagnetism. The experimental results strongly suggest the existence of a pseudogap in the electronic density of states at Fermi energy for the Cu 48.2 Ga 33.8 Mg 3 Sc 15 quasicrystal and the Cu 49 Ga 36 Sc 15 approximant, which has been observed in various stable icosahedral quasicrystals. The electrical resistivity of the Cu 47.1 Ga 32.9 Mg 5 Sc 15 quasicrystal showed a negative temperature coefficient in the temperature region between 2 and 270 K. The Cu 49 Ga 35.8 Sc 15.2 cubic phase showed a positive temperature coefficient in the temperature region. The tendency of the quasicrystal was qualitatively accounted for by the weak localization theory.