Abstract. The ratio of the real (σ₁) and imaginary (σ₂) parts of the ac conductivity of Y_(1−x)Pr_xBa₂Cu₃O_7−δ (x = 0,0.1,0.3,0.4) in the frequency range 0.5–12 MHz and in the temperature range 78–300 K is measured. The agreement between the experimental and theoretical results suggests that the normal state ac conduction behaviour can be successfully explained using a correlated barrier hopping (CBH) model for polarons as carriers. The CBH process is dominant in the higher frequency range (above 2.5 MHz), and at lower frequencies tunnelling of polarons has to be considered to explain the nature of the variation of with ω. This analysis may be considered as supporting evidence for Mott's theory of polaronic conduction in high temperature superconducting materials.

Print publication: Issue 12 (December 2009)
Received 10 August 2009
Published 23 October 2009