Long- to short-range magnetic order in fluorine-doped CeFeAsO

TL;DR

This study investigates how fluorine doping in CeFeAsO alters magnetic order from long-range to short-range, and how superconductivity emerges alongside magnetic suppression, revealing a complex coexistence phase.

Contribution

It provides detailed insight into the evolution of magnetic order and the emergence of superconductivity in fluorine-doped CeFeAsO using muon-spin spectroscopy.

Findings

Long-range magnetic order becomes short-range at x=0.04

Superconductivity appears after magnetic order weakens

Magnetic and superconducting phases coexist nanoscopically

Abstract

The evolution of the antiferromagnetic order parameter in CeFeAsO_{1-x}F_{x} as a function of the fluorine content x was investigated primarily via zero-field muon-spin spectroscopy. The long-range magnetic order observed in the undoped compound gradually turns into a short-range order at x=0.04, seemingly accompanied/induced by a drastic reduction of the magnetic moment of the iron ions. Superconductivity appears upon a further increase in doping (x>0.04) when, unlike in the cuprates, the Fe magnetic moments become even weaker. The resulting phase diagram evidences the presence of a crossover region, where the superconducting and the magnetic order parameters coexist on a nanoscopic range.