Distortion of the crystal field in the van Vleck paramagnet LiTmF 4 activated by isovalent impurities
The spin‐lattice relaxation times of Ce 3+ , Nd 3+ , Yb 3+ ions are measured in LiTmF 4 single crystals at temperatures (1.6 to 5.0 K) and frequencies 9.4 and 23.0 GHz. An observed exponential dependence of the relaxation rate on temperature, T ∼ exp (−Δ/ kT ), shows that relaxation proceeds through...
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Veröffentlicht in: | physica status solidi (b) 1989-03, Vol.152 (1), p.191-201 |
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Hauptverfasser: | , , , , , , , |
Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | The spin‐lattice relaxation times of Ce
3+
, Nd
3+
, Yb
3+
ions are measured in LiTmF
4
single crystals at temperatures (1.6 to 5.0 K) and frequencies 9.4 and 23.0 GHz. An observed exponential dependence of the relaxation rate on temperature,
T
∼ exp (−Δ/
kT
), shows that relaxation proceeds through Van Vleck Tm
3+
host ions, and for the Nd
3+
ion it is possible to distinguish the contributions to relaxation of the nearest and more distant coordination spheres. The distinction of the activation energy Δ from the excitation energy of the lowest Tm
3+
doublet state in the ideal crystal (
32
cm
−1
) is explained by a strong distortion of the crystal field at the Tm
3+
ions nearest to the impurity. Investigations of the optical absorption spectra of Tm
3+
ions in pure and doped LiTmF
4
single crystals are in good agreement with this point of view.
[Russian Text Ignored]. |
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ISSN: | 0370-1972 1521-3951 |
DOI: | 10.1002/pssb.2221520121 |