Universal Features of Terahertz Absorption in Disordered Materials

S. N. Taraskin,^1,2 S. I. Simdyankin,² S. R. Elliott,² J. R. Neilson,^2,3 and T. Lo⁴

¹St. Catharine's College, Trumpington Street, Cambridge CB2 1RL, United Kingdom

²Department of Chemistry, University of Cambridge, Cambridge CB2 1EW, United Kingdom

³Department of Materials Science and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, USA

⁴Teraview Ltd., Platinum Building, St. John's Innovation Park, Cambridge CB4 OW5, United Kingdom

(Received 10 March 2006; published 2 August 2006)

Using an analytical theory, experimental terahertz time-domain spectroscopy data, and numerical evidence, we demonstrate that the frequency dependence of the absorption coupling coefficient between far-infrared photons and atomic vibrations in disordered materials has the universal functional form, C()=A+B², where the material-specific constants A and B are related to the distributions of fluctuating charges obeying global and local charge neutrality, respectively.

©2006 The American Physical Society

URL: http://link.aps.org/abstract/PRL/v97/e055504

doi:10.1103/PhysRevLett.97.055504

PACS: 63.50.+x, 61.43.Fs, 78.30.Ly

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