Spin freezing and magnetic inhomogeneities in bilayer manganites

TL;DR

This study uses muon spin rotation to explore local magnetic structures in electron-doped bilayer manganites, revealing phase separation and spin freezing phenomena that inform a new magnetic phase diagram.

Contribution

It provides new insights into magnetic inhomogeneities and spin dynamics in layered manganites, introducing a revised phase diagram including spin freezing regions.

Findings

Evidence of phase separation into antiferromagnetic and charge-ordered phases.

Observation of spin freezing below 100K for certain doping levels.

Proposal of a new magnetic phase diagram including spin freezing.

Abstract

We have performed a muon spin rotation study on polycrystalline samples of electron-doped layered manganites, La$_{2-2x}$Sr$_{1+2x}$Mn$_2$O$_7$ (0.4< x<1), in order to investigate the local magnetic structure and spin dynamics. Our results provide evidence for phase separation into A-type antiferromagnetic and charge-ordered phases for x=0.52 and spin freezing at low temperatures (T<100K) for 0.52<x<0.75. A new phase diagram which includes this spin freezing region is proposed.