Physics 838 Seminar
09.10.2018 4:00 pm - 5:00 pm
John S. Toll Rm 1201


Speaker: Yun Suk Eo

Title: What we understand and don’t understand about Samarium hexaboride from electrical transport

Topological insulators (TIs) are a subject of recent interest in the condensed matter community due to their unusual electronic properties. Physically, TIs are characterized by the presence of protected metallic surface states located within the bulk gap that is manifested at low temperatures. One of the TI candidates is samarium hexaboride (SmB6), which is especially intriguing because it may be the first strongly correlated TI. It has been several years now since the first experimental report that the conducting surface indeed exists, but its properties are still not well known and the non-trivial nature is under debate. In addition, a recent de-Haas van Alphen quantum oscillation reports that an exotic Fermi surface exists in the electrically insulating bulk of SmB6. In my talk, I will briefly review the recent progress of the study of SmB6, specifically from the electrical transport (in the dc limit) perspective. Then, I will introduce a new way to measure the bulk resistivity of SmB6 in the presence of strong surface conduction at low temperatures (below 4K) using a non-local transport method. Currently, the bulk resistivity at low temperatures is being studied using this technique, and it allows us to study the role of disorder in the bulk. Our results so far show that the bulk resistivity behaves almost like an ideal insulator or an intrinsic semiconductor as if no impurity states in the gap are present. In addition, some of the samples show a small bulk conduction at low temperatures after a very large increase of bulk resistivity. The origin is still not clear yet. Possible scenarios will be discussed in my talk.