Short range magnetic order and effective suppression of superconductivity by manganese-doping in LaFe1-xMnxAsO1-yFy

TL;DR

This study investigates how manganese doping affects magnetic order and suppresses superconductivity in LaFeAsO-based compounds, revealing short-range magnetic order and the persistent absence of superconductivity despite electron doping.

Contribution

It provides new insights into the effects of Mn doping and charge compensation on magnetic and electronic properties in LaFeAsO systems, highlighting pair-breaking effects.

Findings

Mn doping increases unit cell size and reduces semiconducting behavior.

Electron doping suppresses magnetic order in Mn-doped samples.

Superconductivity remains absent despite electronic conditions favorable for pairing.

Abstract

We present a study of the structural and physical properties of directly hole doped LaFe1-xMnxAsO (x = 0.0-0.2) and the influence of charge compensation / electron-doping by additional F doping in LaFe0.9Mn0.1AsO1-yFy (y = 0.1-0.5). High quality polycrystalline samples were prepared using a solid state metathesis reaction. The unit cell increases upon Mn doping, but decreases again when additional F is inserted. The semiconducting character of LaFe1-xMnxAsO decreases with additional F doping. Muon spin relaxation (muSR) measurements reveal short range magnetic order in LaFe1-xMnxAsO and a suppression of magnetism by additional electron-doping with fluoride in LaFe0.9Mn0.1AsO1-yFy. Superconductivity remains absent even though the electronic preconditions are fulfilled in electron-doped LaFe0.9Mn0.1AsO1-yFy at x > 0.1, which is suggestive of effective pair breaking by Mn in this system.