Early experiments on quasicrystals and their approximants revealed their unusual optical properties: no Drude peaks were observed; instead, a.c. conductivity linearly increased with frequency. Several theories have been proposed to explain this linear behaviour. We argue that the observed nearly linear rise in conductivity was an artifact, in good quality samples there should be no linear behaviour. © 1994.
Burkov, S. E., & Rashkeev, S. N. (1994). On optical properties of quasicrystals and approximants. Solid State Communications, 92(6), 525–529. https://doi.org/10.1016/0038-1098(94)90491-X