Investigation of ferroelectric materials by the thermal noise method: Advantages and limitations

ABSTRACT

An overview of the dielectric properties of ferroelectrics by means of thermal noise method from 60s to our days is presented. Different realizations of the thermal noise method are discussed and the advantages and disadvantages are compared for bulk crystals and for thin films. A short overview of the application of the thermal noise method for measurements of dielectric properties of different objects (barium titanate and triglycine sulphate crystals and barium titanate thin films) is presented. The original method for thermal noise voltage characterization, based on digital data processing is demonstrated. The piezoactivity data for barium titanate crystals below phase transition temperature are obtained by thermal noise method. Barkhausen thermal noise data for barium titanate and triglycine sulphate crystals are analyzed below and above the phase transition temperature. The possibility of equivalent circuit analysis for thin ferroelectric films using their noise characteristics is discussed.

KEYWORDS:

• Thermal noise
• ferroelectricity
• thin films
• dielectric permittivity
• equivalent circuit

Acknowledgments

The reported study was partially supported by RFBR (Russian Foundation for Basic Research) (projects 08-02-01010-a, 09-02-05018-6, 11-02-01317-a) and the Czech Science Foundation (Project No. 13-15110S). The authors wish to express their deep gratitude to Prof. Y. Uesu for providing the research group with the BaTiO₃ thin film samples and to Prof. A. Tagantsev for his assistance.