Speaker: Dr Ben Powell (University of Queensland)
Date: 4th September 2009
Condensed matter provides a rich variety of playgrounds for studying the quantum mechanics of large numbers of strongly interacting particles. Yet in condensed matter systems materials issues, such as disorder and the inherent complexity of materials science, often mask the richness of the physics. Therefore an important task for condensed matter physicists is to identify and understand universal properties of matter, i.e. properties are the same in broad classes of materials. This approach has led to many deep insights into quantum many-body physics. I will discuss the history of universal ratios in condensed matter physics and how they have helped us understand the quantum many-body problem. I will then introduce a new ratio, which compares the temperature dependence of a metal’s resistivity to that of its heat capacity, that takes the same (predicted) value in a wide range of strongly correlated metals – despite the numerator and denominator varying by ten orders of magnitude. Finally, I will discuss what we learn about strong correlated electrons from this result.