The three-dimensional electronic structure of the nematic and antiferromagnetic phases of NaFeAs from detwinned ARPES measurements

TL;DR

This study uses detwinned ARPES to reveal the three-dimensional electronic structure of NaFeAs, showing how nematic and antiferromagnetic phases influence its Fermi surface and spectral weight distribution.

Contribution

It provides the first detailed ARPES analysis of NaFeAs's electronic structure across nematic and magnetic phases, emphasizing three-dimensional effects and magnetic coupling.

Findings

Spectral weight is confined to the elliptical electron pocket in the nematic phase.

In the antiferromagnetic phase, the electron pocket is backfolded and hybridizes with hole bands.

The magnetic backfolding wavevector is ($ ext{π}$,0,$ ext{π}$), consistent with neutron scattering results.

Abstract

We report a comprehensive ARPES study of NaFeAs, a prototypical parent compound of the Fe-based superconductors. By mechanically detwinning the samples, we show that in the nematic phase (below the structural transition at $T_s$ = 54 K but above the antiferromagnetic transition at $T_N$ = 43 K) spectral weight is detected on only the elliptical electron pocket along the longer $a_{orth}$ axis. This dramatic anisotropy is likely to arise as a result of coupling to a fluctuating antiferromagnetic order in the nematic phase. In the long-range ordered antiferromagnetic state below $T_N$, this single electron pocket is backfolded and hybridises with the hole bands, leading to the reconstructed Fermi surface. By careful analysis of the $k_z$ variation, we show that the backfolding of spectral weight in the magnetic phase has a wavector of ($\pi$,0,$\pi$), with the $c$-axis component being in agreement with the magnetic ordering in NaFeAs observed by neutron scattering. Our results clarify the origin of the tiny Fermi surfaces of NaFeAs at low temperatures and highlight the importance of the three-dimensional aspects of the electronic and magnetic properties of Fe-based superconductors.