SKM 2023 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 57: Poster: Superconductivity I
TT 57.13: Poster
Thursday, March 30, 2023, 15:00–18:00, P2/OG2
Flat bands of surface states in chiral symmetric superconductors — •Clara Johanna Lapp1,2, Julia M. Link1,2, and Carsten Timm1,2 — 1Institute of Theoretical Physics, Technische Universität Dresden, 01069 Dresden, Germany — 2Würzburg-Dresden Cluster of Excellence ct.qmat, Technische Universität Dresden, 01062 Dresden, Germany
Nodal noncentrosymmetric superconductors can support flat bands of zero-energy surface states in part of their surface Brillouin zone if they obey time-reversal symmetry. These bands are protected by a winding number that relies on chiral symmetry, which in these systems is realized as the product of time-reversal and particle-hole symmetry. We examine which symmetry conditions a model must obey such that a winding number is well defined and can be nonzero. In particular, time-reversal symmetric Bogoliubov-de Gennes Hamiltonians which conserve one spin component can be interpreted as chiral symmetric in each of the spin-blocks and exhibit a nonzero winding number that protects zero energy surface modes. Moreover, we classify which types of sublattice symmetry lead to nonzero winding numbers.