engleski

Intrinsic electrical, magnetic and thermal properties of single-crystalline Al64Cu23Fe13 icosahedral quasicrystalquasicrystal

In order to test for the true intrinsic properties of icosahedral i-Al-Cu-Fe quasicrystals, we performed investigations of magnetism, electrical resistivity, thermoelectric power and thermal conductivity on a single-crystalline Al64Cu23Fe13 quasicrystal, grown by the Czochralski technique. This sample shows superior quasicrystallinity, an almost phason-free structure and excellent thermal stability. Magnetic measurements revealed that the sample is best classified as a weak paramagnet. Electrical resistivity exhibits a negative temperature coefficient with and , whereas the thermopower exhibits a sign reversal at T = 278 K. Simultaneous analysis of the resistivity and thermopower using spectral-conductivity model showed that the Fermi energy is located at the minimum of the pseudogap in the spectral conductivity . Thermal conductivity is anomalously low for an alloy of metallic elements. Comparing physical properties of the investigated single-crystalline Al64Cu23Fe13 quasicrystal to literature reports on polycrystalline i-Al-Cu-Fe material, we conclude that there are no systematic differences between the high-quality single-crystalline and polycrystalline i-Al-Cu-Fe quasicrystals, except for the hindering of long-range transport by grain boundaries in the polycrystalline material. The so far reported physical properties of i-Al-Cu-Fe appear to be intrinsic to this family of icosahedral quasicrystals, regardless of the form of the material.

61.44.Br; 71.23.Ft

This work was supported in a part by the 6th Framework EU Network of Excellence 'Complex Metallic Alloys' (Contract No. NMP3-CT-2005-500140)