By Prof. Nicola Spaldin

ABSTRACT: The behavior of the early early universe just after the Big Bang is one of the most intriguing basic questions in all of science, and is extraordinarily difficult to answer because of insurmountable issues associated with replaying the Big Bang in the laboratory. One route to the answer -- which lies at the intersection between cosmology and materials physics -- is to use laboratory materials to test the so-called "Kibble-Zurek" scaling laws proposed for the formation of defects such as cosmic strings in the early universe. Here I will show that a popular multiferroic material -- with its coexisting magnetic, ferroelectric and structural phase transitions -- generates the crystallographic equivalent of cosmic strings. I will describe how straightforward solution of the Schroedinger equation for the material allows the important features of its behavior to be identified and quantified, and present experimental results of what seem to be the first unambiguous demonstration of Kibble-Zurek scaling in real materials. I will end with some very recent data showing that cosmic strings in multiferroics might be less unambiguous than they seem...