Preprints at http://arxiv.org/abs/1211.6769 and http://arxiv.org/abs/1211.5104 (2012)

The electronic surface states of topological insulators have recently been the subject of intense study by theoreticians and experimentalists alike. A fundamental stumbling block that has so far prevented further inroads being made towards harnessing these surface states for potential applications is the difficulty in distinguishing them from bulk contributions, an irony not lost on many. Zachary Fisk and colleagues present evidence suggesting samarium hexaboride — a so-called Kondo insulator known for decades — is also an ideal topological insulator in which the bulk is completely insulating and the surface highly conducting. Thus, relatively simple transport measurements of the material reveal the properties of the surface conductivity in a manner that has not been possible with other topological insulators such as bismuth selenide. Further work is undoubtedly underway to conclusively prove the origin of these surface states is indeed topological in origin, but what is clear is that there is a new kid on the block for researchers studying topological insulators to focus on.