Change of the charge modulation during superconducting transition in SmFeAsO(0.91)F(0.09) seen by 57Fe M\"ossbauer spectroscopy

TL;DR

This study uses 57Fe Mössbauer spectroscopy to observe how charge density modulation and electric field gradients change during the superconducting transition in SmFeAsO(0.91)F(0.09), revealing insights into electron behavior related to superconductivity.

Contribution

It provides new evidence of charge density wave modulation and electric field gradient changes during superconducting transition in an iron-based superconductor.

Findings

Charge density wave modulation increases near the superconducting transition.

Electric field gradient wave amplitude is partly suppressed during the transition.

The effects differ from those observed in Ba(0.6)K(0.4)Fe2As2 superconductor.

Abstract

Iron-based superconductor SmFeAsO(0.91)F(0.09) has been investigated by the 57Fe Moessbauer spectroscopy versus temperature with the special attention paid to the region of the superconducting transition at about 47 K. Modulation of the electron charge density was found. It leads to the development of the charge density wave (CDW) and electric field gradient wave (EFGW). The modulation of CDW is enhanced in the temperature region of the superconducting gap opening, while the amplitude of EFGW is partly suppressed within this temperature region. This effect is exactly opposite to the similar effect in Ba(0.6)K(0.4)Fe2As2 superconductor. Hence, it seems that d electrons contribute significantly to the Cooper pair formation in both compounds as EFGW is perturbed within the temperature region of the superconducting gap formation.