Reflectance anisotropy of Gd5Si2Ge2 and Tb5Si2.2Ge1.8

Reflectance difference (RD) spectra for the a-b plane of the single crystals of Gd5Si2Ge2 and b-c planes of Gd5Si2Ge2 and Tb5Si2.2Ge1.8 were obtained in the photon energy range of 1.5-5.5 eV. Several peaks were observed for these crystals in the measured spectrum range. Similar features were observed in the RD spectra for the b-c planes of Gd5Si2Ge2 and Tb5Si2.2Ge1.8, while different features were observed for the a-b plane and b-c plane of Gd5Si2Ge2. The RD spectra for the crystals arise not only from the surface anisotropy but also from the bulk anisotropy due to the monoclinic structure of the bulk crystal. (C) 2004 American Institute of Physics.