Fermi surface reconstruction in FeSe under high pressure

TL;DR

This study investigates how high pressure induces Fermi surface reconstruction in FeSe, correlating it with antiferromagnetic order and changes in superconducting properties, revealing significant electronic structure modifications.

Contribution

It provides direct evidence of Fermi surface reconstruction in FeSe under high pressure using SdH oscillations, linking it to antiferromagnetic order and superconductivity suppression.

Findings

Fermi surface reconstructs at ~8 kbar pressure.

Antiferromagnetic order onset coincides with oscillation change.

High ratio of T_c to E_F persists under pressure.

Abstract

We report Shubnikov-de Haas (SdH) oscillation measurements on FeSe under high pressure up to $P$ = 16.1 kbar. We find a sudden change in SdH oscillations at the onset of the pressure-induced antiferromagnetism at $P$ $\sim$ 8 kbar. We argue that this change can be attributed to a reconstruction of the Fermi surface by the antiferromagnetic order. The negative d$T_c$/d$P$ observed in a range between $P$ $\sim$ 8 and 12 kbar may be explained by the reduction in the density of states due to the reconstruction. The ratio of the transition temperature to the effective Fermi energy remains high under high pressure: $k_BT_c/E_F$ $\sim$ 0.1 even at $P$ = 16.1 kbar.