Controlled tuning of atomic structure in functional materials by acoustic waves and electric fields

• Applicant: Professor Dr. Matthias Zschornak
• Subject Area: Experimental Condensed Matter Physics ; Synthesis and Properties of Functional Materials
• Term: from 2019 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 409743569

Active research in the field of condensed matter and nanotechnology not only led to significant progress in understanding the mechanisms of formation of electrical polarization and magnetoelectric phenomena, but also showed the possibilities of creating new classes of devices based on a combination of magnetoelectric and piezoelectric properties. Meanwhile, macroscopic properties, such as multiferroism and piezoelectricity, are associated with local structural changes that occur under the influence of external perturbations. The key ability to control such displacements requires careful study of their connection with the parameters of external fields, and is a fundamental task. Since structural changes at the atomic level caused by external influences are very small, methods for determining atomic displacements with high accuracy are required. New possibilities for that emerged recently due to the novel method developed by the German co-authors of this project (C. Richter et al., Nature Communications 2018), which allows to determine atomic displacements with picometer accuracy using resonant diffraction of synchrotron radiation. In this project, it is proposed to study the transformations in the structural characteristics of a number of piezoelectrics and multiferroics excited by standing acoustic waves and electric fields. For this it is proposed to develop a new method based on the appearance of forbidden Bragg reflections using Resonant X-ray Diffraction of synchrotron radiation and their amplification due to interference effects.It is expected that the results will give a better insight into the mechanisms, controlling the atomic displacement in functional materials under influence of external physical fields, as exemplified by a number of materials, such as such as LiNbO3/LiTaO3, Li2B4O7, Fe2Mo3O8, GaN, ZnO, RbH2PO4, BiFeO3, BaTiO3, and the MFP phase in SrTiO3, and quantitative information regarding the dependence of local atomic displacements on the amplitude and frequency of acoustic waves. Further, new methods for controlled and reversible transformation of structural parameters in functional materials and new experimental equipment compatible both with conventional X-ray sources as well as with the state of the art beamlines at synchrotron radiation facilities will be made available. The obtained results can significantly widen the range of functional materials and can be directly used in modern technological applications.

• DFG Programme: Research Grants
• International Connection: Russia
• Partner Organisation: Russian Foundation for Basic Research