On the nature of the Faraday effect in the rare-earth ortho-aluminate TbAlO3

The magnetic susceptibility chi, the absorption and luminescence spectra, a nd the Verde constant V along different crystallographic axes of the rhombi c crystal TbAlO3 have been investigated experimentally in the temperature i nterval 78-300 K. It is found that, in contrast to the magnetic susceptibil ity chi measured along the [110] axis, the Verde constant V varies in inver se proportion to the temperature in the given range. It is shown that this temperature dependence of the Verde constant measured along the [110] axis is connected with the absence of a contribution to the Faraday rotation of the van Vleck mechanism (in an external field H) of "mixing" of the states of the rare-earth ion Tb3+. From a comparison of the optical and magnetic m easurements, we have determined the wave functions and magnitudes of the St ark intervals between the lower Stark sublevels for the F-7(6) ground multi plet of the Tb3+ ion in the ortho-aluminate TbAlO3. (C) 1999 American Insti tute of Physics. [S1063-7834(99)02811-7].