Broadband dielectric response of CaCu3Ti4O12:: From dc to the electronic transition regime

被引：49

作者：

Kant, C. H. ^{[1
]}

Rudolf, T. ^{[1
]}

Mayr, F. ^{[1
]}

Krohns, S. ^{[1
]}

Lunkenheimer, P. ^{[1
]}

Ebbinghaus, S. G. ^{[2
]}

Loidl, A. ^{[1
]}

机构：

[1] Univ Augsburg, Ctr Elect Correlat & Magnetism, D-86135 Augsburg, Germany

[2] Univ Augsburg, D-86135 Augsburg, Germany

来源：

PHYSICAL REVIEW B | 2008年 / 77卷 / 04期

关键词：

D O I：

10.1103/PhysRevB.77.045131

中图分类号：

T [工业技术];

学科分类号：

08 ;

摘要：

We report on phonon properties and electronic transitions in CaCu3Ti4O12, a material which reveals a colossal dielectric constant at room temperature without any ferroelectric transition. The results of far- and midinfrared measurements are compared to those obtained by broadband dielectric and millimeter-wave spectroscopy on the same single crystal. The unusual temperature dependence of phonon eigenfrequencies, dampings, and ionic plasma frequencies of low-lying phonon modes is analyzed and discussed in detail. Electronic excitations below 4 eV are identified as transitions between full and empty hybridized oxygen-copper bands and between oxygen-copper and unoccupied Ti 3d bands. The unusually small band gap determined from the dc conductivity (similar to 200 meV) compares well with the optical results.

引用

页数：7

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