Transferred hyperfine interactions in Co2P2O7

The transferred hyperfine interaction has been investigated in Co2P2O7 by means of the 31P nuclear magnetic resonance. The expectation values of the cobalt ion spins were determined from the electron spin resonance of Co++ ions in the isomorphous diamagnetic salt Mg2P2O7. The values were confirmed by comparison with bulk susceptibility measurements. The fraction of unpaired electron transferred per Co–O–P path is (0.057 ± 0.005)%. This value is anomalously small compared with previous results of the transferred hyperfine interaction in Mn2P2O7.