“Topologically protected Bogoliubov Fermi surfaces” by Daniel F Agterberg (University of Wisconsin-Milwaukee)

Wednesday, March 1, 2017 - 4:00pm
Condensed Matter Journal Club Seminars

As evidenced by the polar Kerr effect, there are many  superconductors exhibit broken time-reversal symmetry. It is commonly believed that in the absence of disorder or external magnetic field, there are only three types of superconducting excitation gaps in such materials: the gap is nodeless, it has point nodes, or it has line nodes.   I will  show that in the spin-singlet case, the low energy excitation spectrum often does not belong to any of these categories; instead it has Bogoliubov Fermi surfaces. These Bogoliubov Fermi surfaces are topologically protected from being gapped by a Z2 invariant. In this talk, I will discuss the origin, energetic stability, topological stability, and consequences of these Bogoliubov Fermi surfaces.

PAB 4-330