Multiferroic materials are materials that are characterized by both magnetic order and charge order (ferroelectric order). The magnetic order can thus be manipulated with electric fields and vice versa. Typically, the ferroelectric order is arranged in certains domains and the boundary between two domains is called a domain wall. If the polarization in a domain has a component orthogonal to the domain it follows from standard electrostatics that the domain wall will be charged and the result is a two-dimensional metallic system localized at the domain wall.
In a multiferroic material the domain walls may be magnetic as well as metallic and one may obatain a unique two-dimensional magnet that can be manipulated with electric fields (beacause they are charged) and carry stable magnetization that is topologically protected by the domain structure.
The domain structure in multiferroics is currently a promising candidate for future non-volatile memory devices, since the domain boundaries are extremely sharp and allow for very dense data storage based on the domain structure.
In the present project we will unravel the physics of charged domain walls in multiferroic materials using first principles quantum mechanical computer simulations. In particualr we will examine the stability of charged domain walls and investigate the mechanism under which they form. We will then look into their physical properties such as magnetization, conductivity and mobility, which are the relevant quantities to understand if we are to contribute to the design and applicability of novel memory devices.