Topological change of the Fermi surface in ternary iron-pnictides with reduced c/a ratio: A dHvA study of CaFe2P2

TL;DR

This study uses de Haas-van Alphen measurements to reveal a three-dimensional Fermi surface in CaFe2P2, indicating a topological change associated with reduced c/a ratio and diminished nesting in the electronic structure.

Contribution

It provides the first detailed Fermi surface topology of CaFe2P2, highlighting a significant topological change linked to structural parameters in iron-pnictides.

Findings

Fermi surface is highly dispersive along the c-axis

Mass enhancement is approximately 1.5 on all pockets

Fermi surface topology differs from related phosphides, indicating reduced nesting

Abstract

We report a de Haas-van Alphen effect study of the Fermi surface of CaFe2P2 using low temperature torque magnetometry up to 45 T. This system is a close structural analogue of the collapsed tetragonal non-magnetic phase of CaFe2As2. We find the Fermi surface of CaFe2P2 to differ from other related ternary phosphides in that its topology is highly dispersive in the c-axis, being three-dimensional in character and with identical mass enhancement on both electron and hole pockets (~1.5). The dramatic change in topology of the Fermi surface suggests that in a state with reduced (c/a) ratio, when bonding between pnictogen layers becomes important, the Fermi surface sheets are unlikely to be nested.