Anomalous Fermi surface in FeSe seen by Shubnikov-de Haas oscillation measurements

TL;DR

This paper reports the observation of Shubnikov-de Haas oscillations in FeSe, revealing an anomalous Fermi surface with significantly lower carrier density and small Fermi energies, challenging existing band-structure predictions.

Contribution

It provides experimental evidence of an unusual Fermi surface in FeSe, highlighting discrepancies with theoretical models and emphasizing the need for advanced theories including correlations and orbital effects.

Findings

Fermi surface deviates from band-structure calculations

Carrier density is about 0.01 carriers/Fe, much lower than predicted

Effective Fermi energies as small as 3.6 meV

Abstract

We have observed Shubnikov-de Haas oscillations in FeSe. The Fermi surface deviates significantly from predictions of band-structure calculations and most likely consists of one electron and one hole thin cylinder. The carrier density is in the order of 0.01 carriers/ Fe, an order-of-magnitude smaller than predicted. Effective Fermi energies as small as 3.6 meV are estimated. These findings call for elaborate theoretical investigations incorporating both electronic correlations and orbital ordering.