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 Cu48.2Ga33.8Mg3Sc15 and a cubic phase Cu49Ga36Sc15, interpreted as a 1/1 approximant crystal of the quasicrystal. The magnetic susceptibility of the Cu48.2Ga33.8Mg3Sc15 quasicrystal showed an increase from −3.51 × 10−4 to −2.78 × 10−4 m3 kg−1 with a rise in temperature from 120 to 300 K. The Cu49Ga36Sc15 cubic phase showed also a rise from −6.18 × 10−4 to −4.50 × 10−4 m3 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 Cu48.2Ga33.8Mg3Sc15 quasicrystal and the Cu49Ga36Sc15 approximant, which has been observed in various stable icosahedral quasicrystals. The electrical resistivity of the Cu47.1Ga32.9Mg5Sc15 quasicrystal showed a negative temperature coefficient in the temperature region between 2 and 270 K. The Cu49Ga35.8Sc15.2 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.