Nuclear Magnetic Resonance in KMnF3

Abstract

The nuclear magnetic resonance of fluorine in KMn${\mathrm{F}}_3$ has been studied and hyperfine interactions between the fluorine nucleus and the magnetic electrons measured. The values are $A_s=(16.26\mathrm{}\pm 0.4)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$ and $(A_{\sigma }-A_{\pi })=(0.17\mathrm{}\pm 0.1)\times {10}^{-4\mathrm{}}$ ${\mathrm{cm}}^{-1\mathrm{}}$. These values correspond to (0.52±0.02)% $2s$ and (0.18±0.1)% $2p$ character for the unpaired electron. The implications of these results in terms of the $\sigma$ and $\pi$ bonding in this compound are discussed. By a comparison with hyperfine interactions measured in recent paramagnetic resonance studies of KMg${\mathrm{F}}_3$: ${\mathrm{Mn}}^{+2\mathrm{}}$ the amount of distortion in the mixed crystal is estimated. An antiferromagnetic transition is observed at 88.5°K.