M\"{o}ssbauer study of the '11' iron-based superconductors parent compound Fe(1+x)Te

TL;DR

This study uses Mössbauer spectroscopy to analyze the magnetic properties of Fe(1+x)Te, revealing spin density waves and interstitial iron contributions, and how these magnetic features evolve with temperature and iron content.

Contribution

It provides detailed insights into the magnetic structure and interstitial iron effects in Fe(1+x)Te using Mössbauer spectroscopy, a novel application for this compound.

Findings

Spin density wave observed in Fe(1+x)Te at low temperatures.

Interstitial iron contributes additional magnetic spectral components.

Magnetic ordering of interstitial iron diminishes with increasing temperature.

Abstract

57Fe Moessbauer spectroscopy was applied to investigate the superconductor parent compound Fe(1+x)Te for x=0.06, 0.10, 0.14, 0.18 within the temperature range 4.2 K - 300 K. A spin density wave (SDW) within the iron atoms occupying regular tetrahedral sites was observed with the square root of the mean square amplitude at 4.2 K varying between 9.7 T and 15.7 T with increasing x. Three additional magnetic spectral components appeared due to the interstitial iron distributed over available sites between the Fe-Te layers. The excess iron showed hyperfine fields at approximately 16 T, 21 T and 49 T for three respective components at 4.2 K. The component with a large field of 49 T indicated the presence of isolated iron atoms with large localized magnetic moment in interstitial positions. Magnetic ordering of the interstitial iron disappeared in accordance with the fallout of the SDW with the increasing temperature.