Optical and magneto-optical properties and electronic structures of single-crystalline RAl{sub 2} (R=Y, La, Ce, Pr, and Lu)
The diagonal optical conductivity spectra of single crystals of RAl{sub 2} (R=Y, La, Ce, Pr, and Lu) were measured at room temperature by spectroscopic ellipsometry in the 1.5--5.6-eV range. All the compounds exhibit two strong interband absorption peaks at about 1.8 and 3.6 eV for YAl{sub 2} and LuAl{sub 2}, and at about 2.0 and 3.0 eV for LaAl{sub 2}, CeAl{sub 2}, and PrAl{sub 2}. Such differences in the second peak position appear in the theoretical optical conductivity spectra calculated from their band structures obtained by the tight-binding linear-muffin-tin-orbitals method. Most of the contributions to the two peaks in LaAl{sub 2} are from the p and d states, i.e., p{yields}d and d{yields}p transitions, while those involving f states are negligible. These results suggest that f character near E{sub F} for LaAl{sub 2}, CeAl{sub 2}, and PrAl{sub 2} distorts their conduction bands significantly through hybridization, leading to different optical spectra compared to those of YAl{sub 2} and LuAl{sub 2}. The magneto-optical properties of CeAl{sub 2} and PrAl{sub 2} were measured at low temperatures. The Kerr rotation ({Theta}{sub K}) and ellipticity ({epsilon}{sub K}) for both compounds show similar spectral variations with maximum {Theta}{sub K} of 0.35{sup o} and 0.55{sup o} at about 2.1 eV for CeAl{sub 2} and PrAl{sub 2}, respectively. The evaluated off-diagonal conductivity spectra of the two compounds are also similar, with two structures at about 2.1 and 3.8 eV for CeAl{sub 2} and 2.1 and 3.4 eV for PrAl{sub 2}. The energy difference in the second structures is interpreted as due to the different conduction-band structures of the two compounds caused by different hybridization strengths of their f states with conduction bands, because of the difference in their degree of localization.
- Sponsoring Organization:
- (US)
- OSTI ID:
- 40205521
- Journal Information:
- Physical Review B, Vol. 63, Issue 3; Other Information: DOI: 10.1103/PhysRevB.63.035105; Othernumber: PRBMDO000063000003035105000001; 072103PRB; PBD: 15 Jan 2001; ISSN 0163-1829
- Publisher:
- The American Physical Society
- Country of Publication:
- United States
- Language:
- English
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