Regensburg 2019 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 51: Focus Session: Broken Time Reversal Symmetry in Multiband Superconductors
TT 51.3: Hauptvortrag
Donnerstag, 4. April 2019, 10:30–11:00, H2
Topologically protected Bogoliubov Fermi surfaces — •Daniel Agterberg1, Philip Brydon2, Henri Menke2, and Carsten Timm3 — 1Department of Physics, University of Wisconsin - Milwaukee — 2Department of Physics and MacDiarmid Institute for Advanced Materials and Nanotechnology, University of Otago — 3Institute of Theoretical Physics, Technische Universität Dresden
It is commonly believed that, in the absence of disorder or an external magnetic field, there are two possible types of nodal superconducting excitation gaps: the gap has point nodes or it has line nodes. Here, we show that, for an even-parity nodal superconducting state which spontaneously breaks time-reversal symmetry, the low-energy excitation spectrum generally does not belong to either of these categories; instead, it has extended Bogoliubov Fermi surfaces. These Fermi surfaces are topologically protected from being gapped by a non-trivial Z2 invariant. In this talk, I will discuss the physical origin, topological protection, and energetic stability of these Bogoliubov Fermi surfaces, using chiral superconductivity in j=3/2 fermions as a representative example.