Cross-relaxation and phonon bottleneck effects on magnetization dynamics inLiYF4:Ho3+

Semi-ab initio calculations of superposition model and crystal field parameters for Co2+ ions using the exchange charge model

“…[37][38][39][40] 3. Short description of the studied crystals structures, whereas the remaining one (Co(OH) 2 )) has a trigonal structure.…”

19F nuclear spin relaxation and spin diffusion effects in the single-ion magnet LiYF4:Ho3+

“…Having obtained a microscopic expression for the spectral fluctuation density, which can be calculated using known parameters for the titled system [12], we now consider the effect of spin diffusion on the 19 F nuclear magnetization recovery curve. Since in the presence of spin diffusion the relaxation recovery curves are typically non-exponential, it is not possible in general to define a T 1 parameter.…”

“…The spin dynamics at the anti-crossings of the hyperfine sublevels of the ground electronic doublet of Ho 3+ ions produce striking effects at low temperatures, comparable to those observed in SMM. Large peaks (dips) were observed in the magnetic field dependence of the ac-susceptibility [11] and the fluorine nuclear relaxation rate [10] at temperatures in the range 1.7-4 K. The ac-susceptibility results were subsequently described by a microscopic theory [12], while the NMR measurements were analyzed using a phenomenological model [4,5].…”

“…Analysis of the relaxation rates for magnetic fields far from and in between the crossing points allowed us to determine the parameters of nuclear spin-diffusion processes. The previously obtained parameters of Ho 3+ cross-relaxation (CR) processes [12] have been corrected to describe the behavior of fluorine nuclear relaxation as well as of holmium spin dynamics at the anticrossings. In all cases we find our calculations in good agreement with experiments, where the only fitting parameters are associated with 19 F spin diffusion and holmium CR rates.…”

“…In the present work, microscopic calculations of the 19 F nuclear relaxation are carried out by (a) making use of the earlier developed theory of, and calculations for, electronic relaxation in holmium-doped LiYF 4 [12] and (b) by taking into account the consequences of the spin-diffusion theory [18,19]. The experimental data obtained earlier [10] are reanalyzed, and additional measurements have been performed to observe the predicted variation of the fluorine spin-lattice relaxation time at the anti-crossings of electron-nuclear sublevels of Ho 3+ ions with the magnetic field component transverse to the symmetry axis of a crystal.…”