Phonon scattering in quasicrystalline i-Al_{72}Pd_{19.5}Mn_{8.5}: A study of the low-temperature thermal conductivity

TL;DR

This study investigates phonon scattering mechanisms in a quasicrystal by measuring thermal conductivity across a broad temperature range, revealing the roles of tunnelling states and stacking faults in phonon scattering.

Contribution

It provides a detailed analysis of phonon scattering in quasicrystals, highlighting the significance of stacking faults and tunnelling states through experimental measurements and modeling.

Findings

Tunnelling states affect phonon scattering only below 1 K.

Stacking faults are a major source of phonon scattering.

Transmission electron microscopy confirms the presence of stacking faults.

Abstract

We measured the thermal conductivity of an icosahedral quasicrystal i-Al_{72}Pd_{19.5}Mn_{8.5} in the temperature range between 0.4 K and 300 K. The analysis of the low-temperature results was based on a Debye-type model. The results of the analysis for the two temperature regions of 0.4 K <T<40 K and 0.4 K <T<1 K, are not consistent in the sense that a tunnelling-states contribution to phonon scattering is verified only for 0.4 K <T<1 K. The same fitting procedure indicates that structural defects of the stacking-fault type are an important source of phonon scattering. Their physical presence was cleary identified by a transmission electron microscopy experiment.