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arXiv · 0910.0519

Cross-relaxation and phonon bottleneck effects on magnetization dynamics in LiYF4:Ho3+

S. Bertaina·B. Barbara·R. Giraud·B. Z. Malkin·M. V. Vanuynin·A. I. Pominov·A. L. Stolov·A. M. Tkachuk
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Abstract

Frequency and dc magnetic field dependences of dynamic susceptibility in diluted paramagnets LiYF$_4$:Ho$^{3+}$ have been measured at liquid helium temperatures in the ac and dc magnetic fields parallel to the symmetry axis of a tetragonal crystal lattice. Experimental data are analyzed in the framework of microscopic theory of relaxation rates in the manifold of 24 electron-nuclear sublevels of the lowest non-Kramers doublet and the first excited singlet in the Ho$^{3+}$ ground multiplet $^5I_8$ split by the crystal field of S$_4$ symmetry. The one-phonon transition probabilities were computed using electron-phonon coupling constants calculated in the framework of exchange charge model and were checked by optical piezospectroscopic measurements. The specific features observed in field dependences of the in- and out-of-phase susceptibilities (humps and dips, respectively) at the crossings (anti-crossings) of the electron-nuclear sublevels are well reproduced by simulations when the phonon bottleneck effect and the cross-spin relaxation are taken into account.

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S. Bertaina, B. Barbara, R. Giraud, B. Z. Malkin, M. V. Vanuynin, A. I. Pominov, A. L. Stolov, A. M. Tkachuk. 2009-10-03. Cross-relaxation and phonon bottleneck effects on magnetization dynamics in LiYF4:Ho3+. https://doi.org/10.1103/physrevb.74.184421

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