Magnetoelastic Coupling Constants of Rare Earth Ions from Optical-Spectroscopic Data

Measurements are presented of the shifts with uniaxial pressure of the exchange split ${}^2{F}_{\text{7/2}}{\mathrm{(\Gamma }}_7)$ levels of Ce³⁺ in $\mathrm{YIG}$ . By assuming that the pressure shifts of the exchange splittings scale as the unshifted splittings, the Ce³⁺ excited‐state data is used to predict the shifts in the ${}^2{F}_{\text{7/2}}{\mathrm{(\Gamma }}_7)$ ground state of Yb³⁺ in $\mathrm{YIG}$ . The Yb³⁺ shifts are used to predict low‐temperature magnetoelastic coupling constants of Yb³⁺ in $\mathrm{YIG}$ . The predicted constants are in good agreement with those previously measured using a strain gauge.