Quasi-Two-Dimensional Fermi Surfaces and Coherent Interlayer Transport in KFe$_2$As$_2$

TL;DR

This study uses angular-dependent magnetoresistance oscillations to map the Fermi surface shapes in KFe$_2$As$_2$, revealing quasi-two-dimensional Fermi surfaces with rounded-square cross sections and insights into orbital contributions.

Contribution

First detailed mapping of Fermi surface shapes in KFe$_2$As$_2$ using AMROs, revealing quasi-two-dimensional Fermi surfaces with specific cross-sectional shapes.

Findings

Identified two Q2D Fermi surfaces with rounded-square cross sections.

Confirmed FS shape through interlayer transport analysis.

Inferred orbital contributions to the Fermi surfaces.

Abstract

We report the results of the angular-dependent magnetoresistance oscillations (AMROs), which can determine the shape of bulk Fermi surfaces in quasi-two-dimensional (Q2D) systems, in a highly hole-doped Fe-based superconductor KFe$_2$As$_2$ with $T_c \approx$ 3.7 K. From the AMROs, we determined the two Q2D FSs with rounded-square cross sections, corresponding to 12% and 17% of the first Brillouin zone. The rounded-squared shape of the FS cross section is also confirmed by the analyses of the interlayer transport under in-plane fields. From the obtained FS shape, we infer the character of the 3d orbitals that contribute to the FSs.