Giant dielectric permittivity caused by carrier hopping in a layered cuprate Bi 2Ba 2Nd 1.6Ce 0.4Cu 2O 10+ δ

Abstract

The ceramic sample of a layered cuprate Bi 2Ba 2Nd 1.6Ce 0.4Cu 2O 10+ δ , so-called Ba-based Bi-2222 compound was studied by the measurement of the temperature (80–300 K) and the frequency (20–10 6 Hz) dependence of the complex dielectric permittivity. The dielectric constant was measured as high as ∼1000 at 1 kHz and 300 K with relatively low dissipation factor. However, it decreases systematically with decreasing temperature or with increasing frequency due to the dipolar relaxation process. This thermally activated relaxation process plays a dominant role for the low frequency dielectric response. Furthermore, the frequency-dependent ac conductivity was found to obey the power law σ = A ω s . The results were interpreted in terms of Pike's model of hopping transport of localized charge carriers which yields explicitly the ω s behavior and the temperature dependence of s. And we calculated the ionization energy of localized carriers W m = 0.35 eV for the present sample.