Аннотация: High-resolution polarized broadband (1800–23 000 cm−1) optical absorption spectra of Tb3+ in TbFe3(BO3)4 single crystals are studied between room temperature and 4.2 K. The spectral signatures of the structural (R32–P3121, TS = 192 K) and magnetic (TN = 41 K) phase transitions are found and analyzed. Energies and symmetries of the Tb3+ crystal-field (CF) levels were determined for both the high-temperature R32 and the low-temperature P3121 structures of TbFe3(BO3)4 and compared with the calculated ones. It follows unambiguously from the spectral data that the ground state is the Γ1 + Γ2 quasi-doublet of the local D3 point symmetry group for Tb3+ in the R32 high-temperature structure. The CF calculations revealed the CF parameters and wavefunctions for Tb3+ in TbFe3(BO3)4. The value of the Tb–Fe exchange integral and of the effective magnetic field created by the ordered Fe subsystem were estimated as Jfd = 0.26 K and Beff = 3.92 T, using the observed splitting Δ = 32 cm−1 of the Tb3+ ground quasi-doublet at the temperature 5 K. The reliability of the obtained parameters was proven by modeling the literature data on the magnetic susceptibility of TbFe3(BO3)4. Lattice distortions below TS were evidenced by the observed changes of probabilities of the forced electric dipole transitions of Tb3+.
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Держатели документа:
[Popova, M. N.] Russian Acad Sci, Inst Spect, Troitsk 142190, Moscow Region, Russia
[Stanislavchuk, T. N.] New Jersey Inst Technol, Dept Phys, Newark, NJ 07102 USA
[Malkin, B. Z.] Kazan Fed Univ, Kazan 420008, Russia
[Bezmaternykh, L. N.] RAS, Kirenskii Inst Phys, Siberian Branch, Krasnoyarsk 660036, Russia
Доп.точки доступа:
Popova, M. N.; Stanislavchuk, T. N.; Malkin, B. Z.; Bezmaternykh, L. N.; Безматерных, Леонард Николаевич