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Quantum diffusion of electrons in quasiperiodic and periodic approximant lattices in the rare earth-cadmium system

TitleQuantum diffusion of electrons in quasiperiodic and periodic approximant lattices in the rare earth-cadmium system
Publication TypeJournal Article
Year of Publication2016
AuthorsArmstrong, NMR, Mortimer, KD, Kong, T, Bud'ko, SL, Canfield, PC, Basov, DN, Timusk, T
JournalPhilosophical Magazine
Volume96
Pagination1122-1130
Date Published04
Type of ArticleArticle
ISBN Number1478-6435
Accession NumberWOS:000373946000006
Keywordsal70mn9pd21, alloys, approximant, crystals, Drude model, Materials Science, mechanics, Metallurgical Engineering, optical conductivity, physics, quantum diffusion, quasicrystal, reflectivity
Abstract

Icosahedral quasicrystals are characterised by the absence of a distinct Drude peak in their low-frequency optical conductivity and the same is true of their crystalline approximants. We have measured the optical conductivity of i-GdCd [GRAPHICS] , an icosahedral quasicrystal, and two approximants, GdCd [GRAPHICS] and YCd [GRAPHICS] . We find that there is a significant difference in the optical properties of these compounds. The approximants have a zero frequency peak, characteristic of a metal, whereas the quasicrystal has a striking minimum. This is the first example where the transport properties of a quasicrystal and its approximant differ in such a fundamental way. Using a generalised Drude model introduced by Mayou, we find that our data are well described by this model. It implies that the quantum diffusion of electron wave packets through the periodic and quasiperiodic lattices is responsible for these dramatic differences: in the approximants, the transport is superdiffusive, whereas the quasicrystals show subdiffusive motion of the electrons.

DOI10.1080/14786435.2016.1150612
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Complex States

Alternate JournalPhilos. Mag.