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

• Published in: Physical review. B, Condensed matter and materials physics Condensed matter and materials physics, 2006-11, Vol.73
• Main Authors: Bertaina, Sylvain, Barbara, B., Giraud, R., B.Z., Malkin, M.V., Vanuynin, A.I., Pominov, A.L., Stolov, A.M., Tkachuk
• Format: Article
• Language: English
• Subjects: Condensed Matter; Physics; Strongly Correlated Electrons
• ISSN: 1098-0121; 1550-235X
• DOI: 10.1103/PhysRevB.74.184421

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.