Analyses of the optical and magneto-optical spectra of Tb3Ga5O12

Abstract

L 10,9 multiplet manifolds of Tb 3+ ͑4f 8 ͒ in D 2 sites in cubic garnet Tb 3 Ga 5 O 12 ͑TbGaG͒ are investigated at sample temperatures between 1.8 K and room temperature. Absorption measurements extend from 5000 to 340 nm. From analyses of temperature-dependent ͑hot-band͒ absorption spectra, many of the crystal-field split energy ͑Stark͒ levels of the 2S+1 L J multiplet manifolds of Tb 3+ are identified and confirmed from analyses of the fluorescence spectra observed between 485 and 680 nm, representing transitions from the 5 D 4 to the 7 F J manifolds. Each manifold is split by the crystal field into 2J + 1 Stark levels. Some of these manifolds, including the ground-state manifold 7 F 6 , 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 ͑1.8 K͒. To resolve these spectra, we have investigated the Zeeman and magneto-optical spectra for representative manifolds 5 D 4 , 7 F 5 , and 7 F 6 at temperatures of 78 and 85 K and magnetic fields up to 7 kOe. The data are interpreted using the Stark levels and wave functions from a crystal-field splitting calculation that involved 80 individual Stark levels identified from the optical spectra of the 7 F J and quintet states reported in this study. Good agreement is obtained between the calculated and the experimental Stark levels. The calculated energy and symmetry label for each Stark level in the 5 D 4 , 7 F 5 , and 7 F 6 manifolds suitably interpret the spectral properties observed in the magneto-optical spectra, including the experimental assignment reported in the literature for the ground state as a quasidoublet ͕⌫ 1 , ⌫ 2 ͖.

Spectroscopic and magnetic susceptibility analyses of the 7FJ and 5D4 energy levels of Tb3+(4f8) in TbAlO3

“…Stimulated emission from 5 D 4 to 7 F 5 observed at 544 nm has been reported for Tb 3+ in YLF (yttrium lithium fluoride), and is predicted for the same manifoldto-manifold transition in TbAlO 3 [21]. However, excited state absorption (ESA) may limit the efficiency for stimulated emission in the oxide host since Tb 3+ has a number of states at approximately double the 5 D 4 energy [23,24]. On the other hand, infrared absorption bands associated with transitions within the 7 F J manifolds that extend between 1.7 and 5.5 mm can be pumped directly using arrays of infrared diode lasers now available commercially [21].…”

“…Crystal-field modeling generates wave functions for each Stark level that are used to calculate the magnetic susceptibility. In requiring the crystal-field model to interpret both the optical and magnetic properties of TbAlO 3 , we are following an approach similar to that we used earlier in the analyses of the optical and magnetic properties of Tb 3+ and Dy 3+ in the ortho-aluminates TbAlO 3 and DyAlO 3 , and Tb 3+ in the garnets Tb 3 Al 5 O 12 and Tb 3 Ga 5 O 12 [13,14,24].…”

“…The distribution of these so-called ''quasi-doublets'' within the manifold is instrumental in establishing the magnetic properties of the material, especially at low temperature [1,5]. The quasi-doublets can be investigated in greater detail by analyzing the Zeeman and magneto-optical spectra, as we have done earlier for Tb 3+ in Tb 3 Ga 5 O 12 and Tb 3 Al 5 O 12 [24].…”

Terahertz modulation of the Faraday rotation by laser pulses via the optical Kerr effect

“…2 (b) of the signal shows that the dominating oscillation frequency cannot be attributed to either the pump induced coherence between levels of the ground multiplet 7 F 6 of the Tb 3+ ion (1.36 and 2.25 THz) or phonon modes (5.1 and 5.4 THz). 12,[24][25][26] Note that the highest frequency observed in the experiment is about 7.27 THz (Supplementary materials G) indicating that the temporal resolution is not worse than 140 fs. This is much shorter than the pulse duration, which can be mistakingly deduced from the overlap in Fig.…”

Electrically active magnetic excitations in antiferromagnets (Review Article)

“…Magnetic-strictions properties of such garnet were considered in [87]. Investigation the dynamical properties of these interesting systems is just in the beginning [88][89][90]. Recent advance in THz time-domain spectroscopy may stimulate the investigations on a variety of kagome spin structure magnets to uncover the electric-dipole active magnetic resonances in these compounds.…”