Electron-hole asymmetry in Co- and Mn-doped SrFe2As2

TL;DR

This study investigates how electron and hole doping via Co and Mn substitution affects the phase diagram of SrFe2As2, revealing that superconductivity appears only with electron doping and is influenced by structural changes rather than charge doping.

Contribution

It demonstrates the electron-hole asymmetry in SrFe2As2 and highlights the importance of structural modifications over charge doping for superconductivity.

Findings

Superconductivity appears only with Co (electron) doping.

Mn (hole) doping does not induce superconductivity.

Structural changes, especially Fe-As distance, are crucial for superconductivity.

Abstract

Phase diagram of electron and hole-doped SrFe2As2 single crystals is investigated using Co and Mn substitution at the Fe-sites. We found that the spin-density-wave state is suppressed by both dopants, but the superconducting phase appears only for Co (electron)-doping, not for Mn (hole)-doping. Absence of the superconductivity by Mn-doping is in sharp contrast to the hole-doped system with K-substitution at the Sr sites. Distinct structural change, in particular the increase of the Fe-As distance by Mn-doping is important to have a magnetic and semiconducting ground state as confirmed by first principles calculations. The absence of electron-hole symmetry in the Fe-site-doped SrFe2As2 suggests that the occurrence of high-Tc superconductivity is sensitive to the structural modification rather than the charge doping.