Superconducting Mechanism through direct and redox layer doping in Pnictides

TL;DR

This paper investigates how doping in different layers of pnictides influences superconductivity, revealing that redox layer doping is more effective than direct doping in FeAs layers, with Tc reaching up to 47 K.

Contribution

It provides new insights into the doping mechanisms in pnictides, highlighting the effectiveness of redox layer doping over direct FeAs layer doping for enhancing superconductivity.

Findings

Redox layer doping is more effective than direct doping in FeAs layers.

Superconductivity with Tc up to 47 K achieved through F doping in SmFeAsO.

Doping alters the structural and electronic properties, influencing Tc.

Abstract

The mechanism of superconductivity in pnictides is discussed through direct doping in superconducting FeAs and also in charge reservoir REO layers. The un-doped SmFeAsO is charge neutral SDW (Spin Density Wave) compound with magnetic ordering below 150 K. The Superconducting FeAs layers are doped with Co and Ni at Fe site, whereas REO layers are doped with F at O site. The electron doping in SmFeAsO through Co results in superconductivity with transition temperature (Tc) maximum up to 15 K, whereas F doping results in Tc upto 47 K in SmFeAsO. All these REFe/Co/NiAsO/F compounds are iso-structural to ZrCuSiAs structure. The samples are crystallized in a tetragonal structure with space group P4/nmm. Variation of Tc with different doping routes shows the versatility of the structure and mechanism of occurrence of superconductivity. It seems doping in redox layer is more effective than direct doping in superconducting FeAs layer.