Laser spectroscopic study of multiple Eu3+ sites and their crystal fields in YAlG crystals

Resonance fluorescence spectra are excited from a single crystal of europium doped yttrium aluminum garnet. An analysis from the energy spectrum shows that the spectra are due to trivalent europium ions occupying two different sites in the unit cell and a crystal field analysis reveals that these ions at these sites experience fields of orthorhombic and axial symmetry. The former is that expected if Eu3+ replaces the Y3+ at the orthorhombic d sites, the latter if the lanthanide ion replaces the Al3+ ions at the a sites (with a distorted Csub(3i) symmetry), there are indications that Eu3+ prefers the a over the d sites. (Auth.)