Magnetic properties of pure and Gd doped EuO probed by NMR

TL;DR

This study investigates the magnetic properties of pure and Gd-doped EuO using NMR, revealing doping-induced inhomogeneities, their temperature dependence, and how Gd doping affects the exchange interactions.

Contribution

It provides a detailed NMR analysis of Gd-doped EuO, highlighting doping effects on magnetic inhomogeneity and exchange interactions for the first time.

Findings

Gd doping induces temperature-dependent magnetic inhomogeneity.

The exchange integral J increases with Gd doping and remains temperature independent.

Inhomogeneity in Gd-doped EuO is linked to colossal magnetoresistance.

Abstract

An Eu NMR study in the ferromagnetic phase of pure and Gd doped EuO was performed. A complete description of the NMR lineshape of pure EuO allowed for the influence of doping EuO with Gd impurities to be highlighted. The presence of a temperature dependent static magnetic inhomogeneity in Gd doped EuO was demonstrated by studying the temperature dependence of the lineshapes. The results suggest that the inhomogeneity in 0.6% Gd doped EuO is linked to colossal magnetoresistance. The measurement of the spin-lattice relaxation times as a function of temperature led to the determination of the value of the exchange integral J as a function of Gd doping. It was found that J is temperature independent and spatially homogeneous for all the samples and that its value increases abruptly with increasing Gd doping.