Antiferromagnetism of SrFe2As2 studied by Single-Crystal 75As-NMR

TL;DR

This study uses 75As-NMR to investigate the antiferromagnetic and structural transitions in SrFe2As2, revealing similarities and differences with BaFe2As2 in static and dynamic magnetic properties.

Contribution

It provides detailed NMR analysis of SrFe2As2, highlighting the nature of its antiferromagnetic transition and spin fluctuations, and compares these with BaFe2As2.

Findings

Sharp first-order AF and structural transitions occur simultaneously.

Static quantities show similar temperature dependence in SrFe2As2 and BaFe2As2.

Differences in spin fluctuation anisotropy between the two compounds.

Abstract

We report results of 75As nuclear magnetic resonance (NMR) experiments on a self-flux grown high-quality single crystal of SrFe2As2. The NMR spectra clearly show sharp first-order antiferromagnetic (AF) and structural transitions occurring simultaneously. The behavior in the vicinity of the transition is compared with our previous study on BaFe2As2. No significant difference was observed in the temperature dependence of the static quantities such as the AF splitting and electric quadrupole splitting. However, the results of the NMR relaxation rate revealed difference in the dynamical spin fluctuations. The stripe-type AF fluctuations in the paramagnetic state appear to be more anisotropic in BaFe2As2 than in SrFe2As2.