Flexoelectricity in twisted oxide perovskites

• Applicant: Wahib Aggoune, Ph.D.
• Subject Area: Theoretical Condensed Matter Physics
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 510995508

The overall aim of the project is to explore and manipulate the flexoelectric response of complex oxide perovskites by strain engineering. In doing so, the potential of flexoelectricity will be demonstrated, especially with respect to novel properties in twisted perovskite layers. Employing first-principles approaches, we will start with the implementation of flexoelectricity theory in the software package exciting to calculate the flexoelectric response of a series of perovskites in their bulk phases. Our implementation will allow researchers for exploring the flexoelectric effect in other emerging materials. Thereafter, the focus will be on exploring how to control flexoelectricity through distortions. Understanding of the mechanism will also be exploited towards tailoring two-dimensional electron gases (2DEG) formed at interfaces of twisted layers. In particular, we will study interfaces that tend to form screw dislocations. Through the strain gradient, we will determine the flexoelectric response around the dislocations and thus learn how to control it. The roles of twist angle, nature of the material, and lattice mismatch will be analyzed. All this information will allow us to make predictions on how the electronic properties in 2DEG systems will respond.

• DFG Programme: Research Grants
• Co-Investigator: Professorin Dr. Claudia Draxl