engleski

Low-temperature thermal conductivity of icosahedral Al63Cu25Fe12 and Al62Cu25.5Fe12.5 quasicrystals

We present measurements of thermal and electrical conductivity of icosahedral Al63Cu25Fe12 and Al62Cu25.5Fe12.5 quasicrystals in the temperature range 0.1 K-6 K. Electrical conductivity Ds(T)=s(T)-s(4.2 K) of Al63Cu25Fe12, contrary to Ds(T) of Al62Cu25.5Fe12.5, shows a linear increase with up to 2 K, as predicted by electron-electron interaction theories, followed by a strong change of regime at around 2 K. Low-temperature phonon thermal conductivity, kph(T), of Al63Cu25Fe12 shows a deviation from the expected T3 cubic law: in the T-range 0.1 K-0.8 K, kph(T)~T2.7. An anomaly in phonon thermal conductivity appears near 1 K, which superposes to the monotonous increase of kph(T) with T obeyed up to higher T. We suppose that the origin of this anomaly in phonon thermal conductivity is related to the strong change of the regime in the variation of the Ds(T), which appears in the same temperature range. For Al62Cu25.5Fe12.5, kph(T) varies almost linearly between 0.28 and 1.2 K, and exhibits a crossover towards a very rapid variation below 150 mK, much more rapid than T3. There is no evidence for phase transitions from specific heat measurements in the temperature range of the crossover of k(T).

low-T phonon thermal conductivity

Rad je kao poster prezentiran na skupu 7th International conference on quasicrystals (ICQ7), održanom od 20.-24.09.1999., Stuttgart, Njemačka ; objavljen u Zborniku radova.