59Co NMR and nuclear magnetic relaxation study of the magnetic superconductor Y9Co7

The magnetic superconductor Y9Co7 presents in its structure magnetic and non-magnetic Co atoms. A search is made of the 59Co NMR lines attributed in the literature to magnetic Co atoms, with negative results. For the strong 59Co NMR line arising from nuclei of non-magnetic Co atoms the relaxation times T1 and T2 versus temperature are measured directly at 6.5 and 9.0 MHz. A linear dependence on temperature is observed for 1/T1 which can be attributed to interactions with conduction electrons. 1/T2 is not linear with temperature, an effect that is related to the temperature dependence of the magnetization. (author)