# Quantum Oscillations in the Anomalous Spin Density Wave State of FeAs

## TL;DR

This study investigates quantum oscillations in FeAs, revealing discrepancies between experimental Fermi surface data and theoretical predictions, highlighting the influence of electronic correlations on carrier mass enhancement.

## Contribution

It introduces a new crystal growth method and provides detailed experimental data on the Fermi surface in the anomalous spin density wave state of FeAs.

## Key findings

- Evidence for one electron and one hole band in FeAs
- Fermi surface shape differs from theoretical predictions
- Carrier mass is up to four times larger than predicted

## Abstract

Quantum oscillations in the binary antiferromagnetic metal FeAs are presented and compared to theoretical predictions for the electronic band structure in the anomalous spin density wave state of this material. Demonstrating a new method for growing single crystals out of Bi flux, we utilize the highest quality FeAs to perform torque magnetometry experiments up to 35 T, using rotations of field angle in two planes to provide evidence for one electron and one hole band in the magnetically ordered state. The resulting picture agrees with previous experimental evidence for multiple carriers at low temperatures, but the exact Fermi surface shape differs from predictions, suggesting that correlations play a role in deviation from ab initio theory and cause up to a four-fold enhancement in the effective carrier mass.