Author: Ana Smontara, Jean-Claude Lasjaunias, Carley Paulsen, Ante Bilušić, Yvonne Calvayrac

Institute: Centre for Research in Ultra-Low Temperatures, laboratory associated with the Joseph Fourier University, BP 166 X, 38042 Grenoble, France

Low-temperature thermal conductivity of icosahedral quasicrystals Al63Cu25Fe12 and Al62Cu25.5Fe12.5 is the subject of detailed study in the context of modern materials science and condensed matter physics. Quasicrystals, possessing unique symmetry and lack of periodicity, appear as an interesting class of materials demonstrating anomalous thermal conductivity properties.

This paper presents the results of measurements of thermal and electrical conductivity of icosahedral quasicrystals AlKР25Fe12 and Al62KР25.5Fe12.5 in the temperature range from 0.1 to 6 K. Electrical conductivity Δσ(T) = σ(T) − σ(4.2 K) for the Al63Cu25Fe12 alloy, in contrast to Δσ(T) of the Al62Cu25.5Fe12.5 alloy, increases linearly up to 2 K, which corresponds to the predictions of theories of electron-electron interaction, however, at 2 K there is a sharp change in this regime. Low-temperature phonon thermal conductivity κph(T) of the Al63Cu25Fe12 alloy shows a deviation from the expected T^3 law: in the range of T 0.1–0.8 K κph(T)∼T^2,7. Anomalous behavior in the phonon thermal conductivity is observed at a temperature of about 1 K and is combined with a monotonic increase in κph(T) with increasing T. We believe that this anomaly is associated with an abrupt change in the Δσ(T) regime in a similar temperature range. For Al62Cu25,5Fe12,5 κph(T) changes almost linearly between 0.28 and 1.2 K, with a transition to a rapid change at temperatures below 150 mK, which is significantly faster than T^3. Measurements of the heat capacity in the κ(T) transition regions did not reveal phase transitions.

Studies show that the low-temperature thermal conductivity of these alloys is due to the complex spin configuration and interactions between atoms. The unique three-dimensional structure of icosahedral quasicrystals contributes to the easy scattering of phonon, which affects their thermal conductivity. Each of these compounds exhibits its own individual characteristics, which can be associated with both the composition and the presence of various defects in the crystal lattice.

The study of low-temperature thermal conductivity of icosahedral quasicrystals opens new horizons for understanding their fundamental properties and possible applications in high-tech areas such as thermally conductive materials and coolers.