Condensed Matter Physics Seminar: Ida Skogvoll

Abstract: Ferroic materials are defined by the spontaneous emergence of long-range magnetic, electric or elastic order below the critical temperature. This ordering can be switched by a conjugate field and is thus an essential functional property in modern electronics. With the progress in spatial resolution of advanced characterization techniques, these applications are no longer limited to utilizing the bulk state, they also include nanoscale device architectures that functionalize the boundaries separating each ordered domain. These domain walls are 2D topological defects which can be written, moved and erased on demand.
In this talk I will explain how the inherent symmetry-breaking and confined structural distortion in domain walls can enable compelling emergent phenomena, such as polarization in non-polar structures or conductivity in otherwise insulating systems. This includes work on CaMnO3, where density functional theory calculations were used to uncover how the symmetry in ferroelastic domain walls activates a magnetoelectric coupling between the local magnetic order and the induced polar distortion. In addition, I will introduce how we are using machine-learned potentials and the NEP scheme to extend this framework to more complex domain structures, larger scales and finite temperature, with the Ca3Ti2O7 Ruddlesden-Popper structure as our model system.