Electronic structure, magnetic properties and electron transport in Al82.6−xMn17.4Six (4⩽ x ⩽ 16) quasicrystals and approximant crystals

Abstract The magnetic and electronic properties, electron transport properties and the valence band structures were studied in both the icosahedral (I) quasicrystalline phase and the corresponding (1/1 1/1 1/1) approximant phase in a series of Al 82.6− x Mn 17.4 Si x ( x =4, 6, 8, 10.1, 12, 14 and 16) alloys. The magnetic susceptibility obeys the Curie-Weiss-type temperature dependence down to 4 K in both phases, but its value in the 1/1-phase is one order of magnitude smaller than that in the I-phase. The linearly temperature dependent specific heat coefficient λ is distributed in the range 0.1-1 mJ mol −1 K −2 for the 1/1-phase, and in the range 5–7 mJ mol −1 K −2 for the I-phase. Al Ks soft X-ray emission band spectra clearly proved the presence of the pseudogap in both phases. Moreover, the Al 3p states at the Fermi level are less populated in the 1/1-phase than in the I-phase and the pseudogap in the former is wider than the pseudogap in the latter. The large difference observed in the resistivity at 300 K can be attributed to the unique difference in the valence band structure, particularly the Al 3p states, near the Fermi level between the two relevant phases.