Study of Pure and Gadolinium Doped Single Crystals of Europium Monoxide by Nuclear Magnetic Resonance

We performed an Eu and Eu NMR study of EuO and Gd doped EuO using a home-made spectrometer designed to measure signals with fast spin-spin relaxation times. We determined and described the broadening mechanisms giving rise to the structure in the lineshape of pure EuO. The complete description of the lineshape of pure EuO allowed us to highlight the influence of doping EuO with Gd impurities on the lineshape. We demonstrated the presence of a temperature dependent static magnetic inhomogeneity in Gd doped EuO by studying the temperature dependence of the lineshapes. Our results suggested that the inhomogeneity in 0.6% Gd doped EuO was linked to colossal magnetoresistance. We also determined and described the origin and the temperature dependence of both the spin-spin and the spin-lattice relaxation mechanisms. The measurement of the spin-lattice relaxation times as a function of temperature led to the determination of the value of the exchange integral as a function of Gd doping.