Edge-Ferromagnetism from Majorana Flat-Bands: Application to Split Tunneling-Conductance Peaks in the High-Tc Cuprates

Abstract

In mean-field descriptions of nodal d-wave superconductors, generic edges exhibit dispersionless Majorana fermion bands at zero-energy. These states give rise to an extensive ground-state degeneracy, and are protected by time-reversal (TR) symmetry. We argue that the infinite density of states of these flat-bands make them inherently unstable to interactions, and show that repulsive interactions lead to edge FM which splits the flat bands. This edge FM offers an explanation for the observation of splitting of zero-bias peaks in edge tunneling in High-Tc cuprate superconductors. We argue that this mechanism for splitting is more likely than previously proposed scenarios, and describe its experimental consequences.

10 pages, 5 figures

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• Phase transition between the quantum spin Hall and insulator phases in 3D: emergence of a topological gapless phase
• Quantum Hall Ferromagnetism in Graphene
• Majorana Flat Bands and Uni-directional Majorana Edge States in Gapless Topological Superconductors
• The Topological Relation Between Bulk Gap Nodes and Surface Bound States : Application to Iron-based Superconductors

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