Physics Colloquium | 15 April

From multiferroic oxides to cosmology with electronic
structure calculations,
Professeur Nicola Spaldin, Materials Theory, ETH Zürich.

Monday 15 April 2013, 5 pm
École de Physique, Auditoire Stueckelberg
24, quai Ernest-Ansermet, 1211 Genève 4

Abstract: What happened in the early universe just after the Big Bang? This is one of the most intriguing basic questions in all of science, and is difficult to answer because of insurmountable issues associated with replaying the Big Bang in the laboratory. One route to the answer is to use condensed matter systems to test the so-called "Kibble- Zurek" scaling laws for the formation of defects such as cosmic strings that are proposed to have formed in the early universe. In this talk 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 we used electronic structure calculations within the density functional theory framework to identify and quantify the behavior, and show experimental results of the first unambiguous demonstration of Kibble-Zurek scaling.