Presence of magnetic excitations in SmFeAsO

TL;DR

This study investigates magnetic excitations in SmFeAsO, revealing dispersive spin excitations with a bandwidth of about 170 meV, and highlights the influence of structural parameters on magnetic properties in Fe pnictides.

Contribution

First measurement of dispersive spin excitations in SmFeAsO, linking magnetic spectrum features to structural parameters in Fe-based superconductors.

Findings

Magnetic excitations disperse with a bandwidth of ca 170 meV.

Magnetic excitations merge into the elastic line near the $ ext{Γ}$ point.

Structural parameters significantly influence the magnetic excitation spectrum.

Abstract

We measured dispersive spin excitations in $\mathrm{SmFeAsO}$, parent compound of $\mathrm{SmFeAsO_{\text{1-x}}F_{\text{x}}}$ one of the highest temperature superconductors of Fe pnictides (T$_{\text{C}}\approx$55~K). We determine the magnetic excitations to disperse with a bandwidth energy of ca 170 meV at (0.47, 0) and (0.34, 0.34), which merges into the elastic line approaching the $\Gamma$ point. Comparing our results with other parent Fe pnictides, we show the importance of structural parameters for the magnetic excitation spectrum, with small modifications of the tetrahedron angles and As height strongly affecting the magnetism.