Electron-Nuclear Double Resonance ofFe57in MgO

Abstract

The accuracy of the value of the nuclear magnetic moment of ${\mathrm{Fe}}^{57}$ has been increased by a factor of 10 by an electron-nuclear double resonance measurement in the ${\mathrm{Fe}}^{3+}$ state in MgO, where the paramagnetic shielding correction is less than 1 part in ${10}^3$. The value found is ${\mu }_I\left({\mathrm{Fe}}^{57}\right)=+0.09024\mathrm{}\pm 0.00007$ nm. Ludwig and Woodbury's earlier determination, +0.0903±0.0007 nm, is in excellent agreement with this result, although approximately ten times less accurate. An additional term in the hyperfine interaction of the type $S^{3}I$ was observed. The hyperfine field at the ${\mathrm{Fe}}^{57}$ nucleus is shown to differ by less than ½% from the value found by Robert for ${\mathrm{Fe}}^{3+}$ in octahedral coordination in yttrium iron garnet (YIG). Thus, whatever zero-point spin deviation may be present in YIG is apparently less than anticipated theoretically.