Sang-Wook Cheong: Topological Vortex Domains in Quantum Materialss

Charge/spin/orbital order in quantum materials accompanies directional variants and translational variants. The large-range domain wall configuration of these variants can be associated with non-trivial topologies and topological vortex defects. In addition, the temporal evolution of the domain wall configuration and topological vortices or their changes with external stimuli can strictly follow topological charge conservation laws. We also found that if the relevant phase transition is continuous, the formation kinetics of topological vortices follows the so-called Kibble-Zurek mechanism, which is important to understand the early stage of universe after big bang. Thus, a tiny single crystal of quantum materials can be a test bed for the development of this cosmos. Statistical analysis of the spatial distribution of vortex domains in certain compounds unveils a power law, which resembles the effect of "the rich get richer". We will discuss a number of intriguing exemplary cases in compounds such as multiferroic R(Mn,Fe)O3, hybrid improper ferroelectric (Ca,Sr)3Ti2O7 and antiferromagnetic-superconducting Sr2VO3FeAs.