Nuclear magnetic resonance in ferromagnetic HCP and FCC 59cobalt

The 59Co nuclear magnetic resonance spectra of powdered metal have been investigated in the temperature range from 3K - 295K. Both HCP resonance lines, coming from nuclei at the center and the edge of the domain walls (γ1 = 221 MHz, γ2 = 214 MHz at 295 K, respectively) have been observed as in bulk material. The quadrupole splitting, directly measured only by Kawakami et al., was verified. The line spacing γsub(q) = 3e2Qq/2I(2I-1)h is γsub(q) = (178 +- 5) kHz at 295 K. A new line with γ = 221.7 MHz at 295 K was found, which is probably due to a stacking fault. The temperature behavior of the FCC-linewidth is anomalous. Between 3 and 10 K a line splitting due to frequency pulling, already predicted by De Gennes et al. in 1962, was discovered. The frequency shift derived from the splitting of the FCC line at 3 K is delta ω0 approximately 2.51 MHz. The corresponding anisotropy field and zero field ferromagnetic resonance frequency of FCC cobalt are Hsub(A) approximately 1.25 X 102 Oe and ωsub(e) approximately 2.27 X 109 Hz, respectively. (Auth.)