Gap structure in Fe-based superconductors with accidental nodes: the role of hybridization

TL;DR

This paper investigates how hybridization between electron pockets in Fe-based superconductors affects the gap structure, revealing three possible modifications to the nodal points, including shifting, merging, or emergence of new nodes.

Contribution

It introduces a detailed analysis of hybridization effects on accidental nodes in Fe-based superconductors, highlighting three distinct outcomes on the gap structure.

Findings

Hybridization shifts nodal positions.

Nodes can merge and vanish.

New nodal points can emerge, doubling the original number.

Abstract

We study the effects of hybridization between the two electron pockets in Fe-based superconductors with s-wave gap with accidental nodes. We argue that hybridization reconstructs the Fermi surfaces and also induces an additional inter-pocket pairing component. We analyze how these two effects modify the gap structure by tracing the position of the nodal points of the energy dispersions in the superconducting state. We find three possible outcomes. In the first, the nodes simply shift their positions in the Brillouin zone; in the second, the nodes merge and disappear, in which case the gap function has either equal or opposite signs on the electron pockets; in the third, a new set of nodal points emerges, doubling the original number of nodes.