AndreaBianchi

Professeur adjoint

GeneralizedUmklappScatteringInTheThermalTransportOfQuasicrystals

Filed in: Site.GeneralizedUmklappScatteringInTheThermalTransportOfQuasicrystals · Modified on : Wed, 08 May 19


Comparison glass-quasicrystal-crystal

Quasicrystals have a perfectly ordered structure, however they lack translational symmetry. Instead, the crystal structure is self-similar and if structural elements are grouped together, the same structure is found as before, only inflated by the golden mean. This has profound effects on the physical properties of quasicystals. Instead of one characteristic length scale which in periodic crystals is given by the size of the unit cell, there is a series of characteristic length scales.

As a consequence Umklapp scattering, which in periodic crystals leads to a characteristic maximum of the phonon thermal conductivity ph, we observed a much weaker maximum in the phonon thermal conductivity of icosahedral quasicrystals. The series of length scales also results in a power law temperature dependence of ph above the maximum, instead of an exponential temperature dependence as observed in periodic crystals (1,2). To this day, this finding remains one of the few where it was possible to directly relate the aperiodic crystals structure of quasicrystals to a physical property.

  1. P. A. Kalugin, M. A. Chernikov, A. D. Bianchi and H. R. Ott, “Structural scattering of phonons in quasicrystals”, Phys. Rev. B 53, 14145, (1996).
  2. M. A. Chernikov, A. Bianchi, and H. R. Ott, “Low-temperature thermal conductivity of icosahedral Al70Mn9Pd21”, Phys. Rev. B 51, 153 (1995).

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