Heavy Fermions, Rise of the Topologies

The electrons in Heavy fermion materials are subject to spin-orbit coupling interactions that greatly exceed their Kinetic energy. It has long been known that the spin orbit coupling stablizes new kinds of heavy fermion metals, superconductors and ``Kondo insulators'' against the competing state of magnetism. In this talk I will discuss the new realization that spin orbit copling can influence the ground state, changing its topology and giving rise to Topological Kondo insulators. We'll look at samarium hexaboride, SmB6, ``the worlds oldest topological insulator,'' a Kondo insulator discovered 45 years ago, predicted to be topological in 2011, and tentatively confirmed to be so in a series of hot new experimental studies of the past few months. I'll discuss a simple model for a topological Kondo insulator and introduce the most recent measurements, including ARPES, de Haas van Alphen and weak antilocalization that appear to support the idea that this is a strongly interacting topological insulator in which the surface conductance is carried by electrons on spin-orbit coupled Dirac cones. We'll also discuss the open unanswered questions surrounding this topic.