A review of NMR studies in RCo3 systems presenting d-moment instability

For the past few years, intermetallic systems with the formula RCo3, where R is a rare earth, have attracted the attention of the magnetism community. In these systems, the magnetism associated to the Co ions presents a magne tic instability which gives rise to metamagnetic phase transitions observed as a change on the Co magnetic moment for some critical values of the mole cular field acting on this sublattice. A number of publications about these systems is concerned with basic magnetic measurements and Co-59 NMR in com pounds such as Y1-xRxCo3, where R = Gd, Nd, Er. The Co ions are distributed among three crystal sites with different symmetries, one of these sites be ing further split into two magnetic sites, a fact in itself that considerab ly complicates the NMR spectra. Besides, as we have observed, the linewidth s and even the number of lines appearing on the NMR spectra are strongly de pendent on some NMR features, such as the radiofrequency power applied to t he sample. Adding to this fact, these magnetic peculiarities depend on the compounds stoichiometry; therefore it is no surprise to find conflicting re sults in the literature. In the present paper a review of the NMR published data will be made, including some new results of our own.