Phase dependent NMR spectra of Co-rich CoV alloys

Abstract

Nuclear spin echo spectra are observed for three phases ( alpha H, alpha I, alpha L) of CoV alloys with 11.4-21.8 at.% V at 4.2K in zero external field. The 59Co spectra have three peaks and the hyperfine fields corresponding to the peak frequencies at 15.0 at.% V are: 136, 155, 174 kOe for the alpha H phase; 137, 165 195 kOe for the alpha I phase; and 141, 168, 201 kOe for the alpha L phase. On the reasonable assumption that Co atoms with more than four vanadium atoms at their nearest-neighbour (NN) sites do not have magnetic moments, the hyperfine fields obtained in a given phase are attributed, in order from the largest value, to Co atoms with one, two and three vanadium atoms at the NN sites, respectively. These Co atoms with one to three V neighbours seem to have well defined localised moments that do not differ very much from those in Co metal.