Colloquium on June 6, 2011

Piers Coleman
Rutgers University
Center for Materials Theory, Department of Physics and Astronomy

Magnetism and Superconductivity: A new era of convergence in condensed matter physics.

Three years after the discovery of superfluid He-3 was discovered, Physicists first observed heavy fermion superconductivity, yet the open mind-set required to embrace these results as a discovery, rather than a materials artifact was lacking. It took the efforts of a brave and determined set of heavy electron pioneers, to overcome this resistance and change the mind-set.  It is fasincating to imagine how our field might have changed if our community could have been wildly more adventurous.  Moreover, it poses the interesting question - how can we avoid the conservative errors of the past to embracing todays new challenges posed by strongly correlated electron materials?

Today, we are increasingly concious of the convergence of magnetism and superconductivity in condensed matter physics, of the central role of spin as a driver for heavy electron metals and superconductors - not just as the glue of pairing - but as the basic fabric of these materials.  Many of us suspect that the nexus of these phenomena lies at the quantum critical point that appears to present in heavy electron, cuprate and iron-based superconductors.

I'll talk about how our ideas about spins and their role in correlated electron physics are changing.  I want to talk about the severe challenges the physicists face in trying to describe the incompressible spin component of these materials.  I'll discuss the all-important linksm between f- and d-electron materials and some of the new kinds of order we are encountering, including a hidden and topological order.