Stress-Induced Angular Momentum Quenching in MgO: ${\mathrm{Fe}}^{2+}$ as Observed by Mössbauer Spectroscopy

Under the influence of a suitable uniaxial stress, the quenching of the electronic angular momentum of the low-lying threefold degenerate ${\Gamma }_{5g}$ level of ${\mathrm{Fe}}^{2+}$ in cubic MgO has been observed by Mössbauer spectroscopy. The result is consistent with Ham's model for the appearance of a quadrupole doublet at low temperatures. A value for the strain coefficient of ${\mathrm{Fe}}^{2+}$ in MgO has been obtained: $G_{11}=585\mathrm{}$ ${\mathrm{cm}}^{-1\mathrm{}}$.