Nesting of electron and hole Fermi surfaces in non-superconducting BaFe_2P_2

TL;DR

This study provides a detailed Fermi surface mapping of BaFe_2P_2, revealing nesting features and a warped hole surface that may relate to the nodal gap structure, challenging assumptions about nesting and superconductivity.

Contribution

It offers the first comprehensive dHvA measurements of BaFe_2P_2, showing detailed Fermi surface topology and its implications for superconductivity and nesting.

Findings

Nesting between hole and electron surfaces in non-superconducting BaFe_2P_2

Presence of a highly warped hole surface possibly linked to nodal gaps

Improved nesting does not correlate with increased pairing strength

Abstract

We report detailed measurements of the de Haas-van Alphen (dHvA) effect in BaFe_2P_2 which is the end member of the superconducting series, BaFe_2(As_{1-x}P_x)_2. Using high purity samples we are able to observe dHvA oscillations from all the sheets of Fermi surface and hence build up a complete detailed picture of its structure. The results show the existence of a highly warped section of hole surface which may be the origin of the nodal gap structure in this series. Importantly, we find that, even for this non-superconducting end member, one of the hole surfaces almost exactly nests with the inner electron surface. This suggests that improved geometric nesting does not drive the increase in pairing strength with decreasing x in this system.