Temperature-independent giant dielectric response in transitional BaTiO3 thin films

Arnoud S. Everhardt, Thibaud Denneulin, Anna Grünebohm, Yu Tsun Shao, Petr Ondrejkovic, Silang Zhou, Neus Domingo, Gustau Catalan, Jiří Hlinka, Jian Min Zuo, Sylvia Matzen, Beatriz Noheda

Research output: Contribution to journalArticlepeer-review

Abstract

Ferroelectric materials exhibit the largest dielectric permittivities and piezoelectric responses in nature, making them invaluable in applications from supercapacitors or sensors to actuators or electromechanical transducers. The origin of this behavior is their proximity to phase transitions. However, the largest possible responses are most often not utilized due to the impracticality of using temperature as a control parameter and to operate at phase transitions. This has motivated the design of solid solutions with morphotropic phase boundaries between different polar phases that are tuned by composition and that are weakly dependent on temperature. Thus far, the best piezoelectrics have been achieved in materials with intermediate (bridging or adaptive) phases. But so far, complex chemistry or an intricate microstructure has been required to achieve temperature-independent phase-transition boundaries. Here, we report such a temperature-independent bridging state in thin films of chemically simple BaTiO3. A coexistence among tetragonal, orthorhombic, and their bridging low-symmetry phases are shown to induce continuous vertical polarization rotation, which recreates a smear in-transition state and leads to a giant temperature-independent dielectric response. The current material contains a ferroelectric state that is distinct from those at morphotropic phase boundaries and cannot be considered as ferroelectric crystals. We believe that other materials can be engineered in a similar way to contain a ferroelectric state with gradual change of structure, forming a class of transitional ferroelectrics. Similar mechanisms could be utilized in other materials to design low-power ferroelectrics, piezoelectrics, dielectrics, or shape-memory alloys, as well as efficient electro- and magnetocalorics.

Original languageEnglish (US)
Article number011402
JournalApplied Physics Reviews
Volume7
Issue number1
DOIs
StatePublished - Mar 1 2020
Externally publishedYes

ASJC Scopus subject areas

  • General Physics and Astronomy

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