Nonexponential photon-echo decays of paramagnetic ions in the superhyperfine limit

Abstract

Nonexponential photon-echo decays are observed in ruby, ${\mathrm{Er}}^{3+}$:${\mathrm{YLiF}}_{4}$, and ${\mathrm{Er}}^{3+}$:${\mathrm{LaF}}_{3}$ with samples of low ion concentrations in high (10--50 kG) magnetic fields. At the highest fields, photon-echo decays are field independent and their temporal forms are identical for all three systems. This behavior is attributed to optical dephasing arising from electron-spin nuclear-spin superhyperfine interactions in the presence of a frozen core.