Observation of Jonscher Law in AC Hopping Conduction of Electron-Doped   Nanoporous Crystal 12CaO7Al2O3 in THz Frequency Range
  We have performed terahertz time-domain spectroscopy of carrier-doped nanoporous crystal 12CaO7Al2O3 showing the Mott variable range hopping at room temperature. The real part of the dielectric constant clearly demonstrates the nature of localized carriers. The frequency dependence of both the real and imaginary parts of the dielectric constant can be simply explained by assuming two contributions: a dielectric response by the parent compound with no carriers and an AC hopping conduction with the Jonscher law generally reported up to GHz range. The possible obedience to the Jonscher law in the THz range suggests a relaxation time of the hopping carriers much faster than 1ps in the carrier-doped 12CaO7Al2O3. 
H. Harimochi, J. Kitagawa, M. Ishizaka, Y. Kadoya, M. Yamanishi, S.   Matsuishi, H. Hosono