Superconductivity induced by ruthenium substitution in an iron arsenide: investigation of SrFe2-xRuxAs2 (0 <= x <= 2)

TL;DR

This study shows that substituting ruthenium for iron in SrFe2As2 suppresses magnetic order and induces bulk superconductivity with Tc up to 20K, supported by experimental and theoretical analyses.

Contribution

It demonstrates that isovalent Ru substitution effectively suppresses magnetism and induces superconductivity in SrFe2As2, expanding understanding of doping effects in iron arsenides.

Findings

Superconductivity appears for 0.6 <= x <= 0.8 with Tc ~20K.

Ruthenium substitution suppresses magnetic order.

Structural changes include a decrease in the c/a lattice parameter ratio.

Abstract

The magnetism in SrFe2As2 can be suppressed by electron doping through a small substitution of Fe by Co or Ni, giving way to superconductivity. We demonstrate that a massive substitution of Fe by isovalent ruthenium similarly suppresses the magnetic ordering in SrFe2-xRuxAs2 and leads to bulk superconductivity for 0.6 <= x <= 0.8. Magnetization, electrical resistivity, and specific heat data show Tc up to approx 20K. Detailed structural investigations reveal a strong decrease of the lattice parameter ratio c/a with increasing x. DFT band structure calculations are in line with the observation that the magnetic order in SrFe2-xRuxAs2 is only destabilized for large x.