The superconductor KxSr(1-x)Fe2As2: Normal state and superconducting properties

TL;DR

This study explores the normal and superconducting phases of KxSr(1-x)Fe2As2, revealing how magnetic order and Fermi surface changes influence its superconducting properties across different compositions.

Contribution

It provides detailed insights into the phase diagram, critical fields, and Fermi surface reconstruction in KxSr(1-x)Fe2As2, highlighting the interplay between magnetism and superconductivity.

Findings

H_{c2}(0) scales with T_c

Seebeck coefficient changes near x=0.3

Fermi surface reconstructs with magnetic order

Abstract

The normal state and superconducting properties are investigated in the phase diagram of K_xSr_{1-x}Fe_2As_2 for 0<x<1. The ground state upper critical field, H_{c2}(0), is extrapolated from magnetic field dependent resistivity measurements. H_{c2}(0) scales with the critical temperature, T_c, of the superconducting transition. In the normal state the Seebeck coefficient is shown to experience a dramatic change near a critical substitution of x=0.3. This is associated with the formation of a spin density wave state above the superconducting transition temperature. The results provide strong evidence for the reconstruction of the Fermi surface with the onset of magnetic order.