PULSED NUCLEAR-MAGNETIC-RESONANCE OF CO-59 IN CO3S4

Nuclear magnetic resonance of Co-59 in Co3S4, which had been considered to be a simple Pauli paramagnet, has been reinvestigated by a pulsed method. Free-induction decay or spin-echo signals from A and B sites in the spinel structure have been observed. The signal from the magnetic A site shows a temperature-dependent Knight shift, and disappears suddenly at 58 K with decreasing temperature, suggesting the onset of a magnetically ordered state. The hyperfine coupling constant is roughly estimated to be - 10 kOe/mu-B from the K-chi plot. The signal from the nonmagnetic B site, which shows a textbooklike quadrupolar powder pattern, is strong at low temperatures but the effect of the magnetic A site on the B site was not detected. The nuclear spin-lattice relaxation shows the Korringa-type behavior with (T1T)-1 = 13 +/- 2 (s K)-1 for Co-59 at the A site.