Analyses of the optical and magneto-optical spectra of Tb3Ga5O12

Abstract

Absorption spectra of the FJ7, D4,3,25, G6,5,45, and L10,95 multiplet manifolds of Tb3+ (4f8) in D2 sites in cubic garnet Tb3Ga5O12 (TbGaG) are investigated at sample temperatures between 1.8K and room temperature. Absorption measurements extend from 5000to340nm. From analyses of temperature-dependent (hot-band) absorption spectra, many of the crystal-field split energy (Stark) levels of the LJ2S+1 multiplet manifolds of Tb3+ are identified and confirmed from analyses of the fluorescence spectra observed between 485 and 680nm, representing transitions from the D45 to the FJ7 manifolds. Each manifold is split by the crystal field into 2J+1 Stark levels. Some of these manifolds, including the ground-state manifold F67, consist of Stark levels that are accidentally degenerate, or nearly so, making transitions to or from these levels appear as unresolved spectra, even at the lowest temperature investigated (1.8K). To resolve these spectra, we have investigated the Zeeman and magneto-optical spectra for repres...