Estudos dos compostos pseudobinários Ho1-xGdxAl2 via ressonância magnética nuclear em campo zero

Abstract

In this study, the zero field nuclear mgnetic resonance technique was applied for obtaining NMR spectra and quadrupolar coupling of 27Al nuclei in samples of Ho1-xGdxAl2 for x= 0, 0,25, 0,5 and 0,75. The value of the quadrupolar coupling was determined using the measurement experiment of the quadrupole oscillations in 4,2 K. The NMR spectra of nuclei 27Al were obtained at various temperatures using the Hahn echo experiment by varying the excitation frequency between 6 and 65 MHz. These spectra were obtained at temperatures between 4.2 K and the spontaneous spin reorientation temperature (TRS). The results from the integration of the spectra show a correlation between the area under the spectra at different tempetatures. A larger area is observed in the spin reorientation temperature, which can therefore be used to characterize this transitions in a zero field NMR spectrum. The results were analyzed using a simple model used for the calculation of resonance frequencies, which show a good agreement with the experimental results.