Isoelectronic Ru substitution at Fe-site in Sm(Fe1-xRux)As(O0.85F0.15) compound and its effects on structural, superconducting and normal state properties

TL;DR

This study investigates how isoelectronic Ru substitution at Fe sites in Sm(Fe1-xRux)As(O0.85F0.15) affects structural, superconducting, and normal state properties, revealing two distinct regimes with different behaviors.

Contribution

It provides a combined experimental and theoretical analysis of Ru substitution effects, clarifying the role of structural disorder in superconductivity suppression and magnetic frustration.

Findings

Superconductivity is strongly affected in Fe-rich phase (x<0.5) due to disorder.

Ru-rich phase (x>0.5) shows metallic behavior with suppressed magnetic moments.

Lack of spin fluctuations correlates with the suppression of superconductivity.

Abstract

In this work we present a systematic experimental and theoretical study of the structural, transport and superconducting properties of Sm(Fe1-xRux)As(O0.85F0.15) polycrystalline samples as a function of Ru content (x) ranging from 0 to 1. The choice of Ru as isoelectronic substitution at Fe site of F-doped compounds allows to better clarify the role of structural disorder in modifying the normal and superconducting properties of these newly discovered multiband superconductors. Two different regions are identified: the Fe-rich phase (x<0.5) where superconducting and normal state properties are strongly affected by disorder induced by Ru substitution; the Ru-rich phase (x>0.5) where the system is metallic and strongly compensated and the presence of Ru frustrates the magnetic moment on Fe ions. Here the lack of magnetic features and related spin fluctuations may be the cause for the suppression of superconductivity.