Magnetization and polarization dynamics in complex multiferroic oxides

Biplab Sanyal
Biplab Sanyal. Photo: Camilla Thulin

The Swedish Research Council reached a decision on February 23, 2017 on project grants and starting grants on Natural and Engineering Sciences. The Department of Physics and Astronomy is granted 45.9 million SEK for the period 2016-2020 for in total six project grants and six starting grants. The projects will begin during 2017.

Project description

Biplab Sanyal, Materials Theory, was granted 2.55 million SEK for the project “Magnetization and polarization dynamics in complex multiferroic oxides” from the Swedish Research Council for the period 2016-2020.

Project description

Our society has a constant need of technological innovations for a better future. To achieve this goal, we need new materials with multifunctional properties to have miniaturized devices having multitasking capabilities. One of the most important application areas is information and communication technology. Magnetism and magnetic materials have a long history of important technological applications where they are used abundantly in computer hard disks, tape-recorders, magneto-optical storage devices, credit cards etc. in daily life. To enhance the efficiency of data-storage devices, the microscopic understanding of the dynamical processes under external fields are essential.

The goal of this project is the development and application of theoretical tools to understand and predict the properties of complex multiferroic oxides. These multifunctional materials may overcome the limitations of conventional devices by combining several functionalities in one single device. The inherent multifunctional nature of the multiferroic materials is revealed in the simultaneous presence of magnetic, and electric order parameters and also a coupling between them in some cases, giving rise to the possibility of controlling the polarization (magnetization) by an external magnetic (electric) field. Though a lot of research has been done in connection to the static properties, the time-dependent properties have been rarely studied. The central theme of this project is to understand the polarization and magnetization dynamics in a quantum mechanical way, i.e., how the atoms and their magnetic moments change with time. The knowledge of the relevant time scales and the microscopic understanding of the dynamical processes will be of significant importance in interpreting the experimental results and to develop fast and efficient multifunctional devices in future.

The theoretical modeling of static properties will be done using first principles density functional theory (DFT) for which Walter Kohn was awarded the Noble prize in Chemistry in 1998. The time dependence of magnetic moments will be studied using atomistic spin dynamics simulations. New computational techniques will be developed to combine spin dynamics with atomic dynamics to study the time evolution of polarization and magnetization on the same footing.