Inflated nodes and surface states of topological superconductors

In the talk, I will consider two examples. First, noncentrosymmetric superconductors with spin-orbit coupling generically show mixing of singlet and triplet Cooper pairs and have energy gaps with line nodes in momentum space. These are associated with flat zero-energy bands of Majorana surface states with interesting magnetic properties. Second, centrosymmetric materials in which superconductivity breaks time-reversal invariance are even more exotic. I will argue that they generically show extended, two-dimensional Fermi surfaces (see figure). Such Fermi surfaces are of course the hallmark of normal metals but here they are both topologically protected and energetically stable in superconductors.