Specific-heat and susceptibility studies of powdered Ni(${\mathrm{C}}_2$ ${\mathrm{H}}_8$ ${\mathrm{N}}_2$ ${)}_2$Ni(CN${)}_4$ have been performed from 50 mK to 20 K, and magnetization measurements have been conducted at 4.3 K in magnetic fields up to 6 T. The results show that Ni(${\mathrm{C}}_2$ ${\mathrm{H}}_8$ ${\mathrm{N}}_2$ ${)}_2$Ni(CN${)}_4$ is an S=1 antiferromagnetic Heisenberg chain with a strong planar anisotropy. The low-temperature specific-heat data show a contribution due to magnetic excitations which are interpreted within the framework of a strong coupling theory of (anti)excitons.

Results of ac-susceptibility, specific-heat, magnetization, and electron-spin-resonance studies of a $\left[{\text{Gd}}_2{\left(\text{fum}\right)}_3{\left({\text{H}}_2\text{O}\right)}_4\right]\cdot 3{\text{H}}_2\text{O}$ ($\text{fum}=\text{fumarate}$, ${\text{C}}_4{\text{H}}_2{\text{O}}_4$) powder samples are reported. The results of these measurements enabled us to identify the studied compound as a three-dimensional $S=7/2$ Heisenberg magnet with $T_N=0.19\text{K}$ and dominant crystal-field anisotropy. The susceptibility studies conducted at audio frequencies and temperatures from 2 to 30 K revealed that the application of static magnetic fields induces a slow spin relaxation. The relaxation is not associated with an anisotropy energy barrier and is explicable assuming resonant phonon trapping. The magnetic field dependence of the relaxation time is consistent with the proposed scenario and suggests that a strong spin-lattice interaction may be the mechanism governing the relaxation properties in the studied system.

Magnetocaloric properties of ${\text{KEr}\left({\mathrm{MoO}}_4\right)}_2$ single crystals were investigated using magnetization and specific heat measurements in the magnetic field applied along the easy and hard axis. Large conventional magnetocaloric effect was found around 10 K ($-\mathrm{\Delta }{S}_{\max }=14$ J/kg K for 5 T) in the field applied along the easy axis. What is more, a huge magnetic anisotropy in the $ab$ plane leads to a large anisotropy of magnetocaloric effect, $-\mathrm{\Delta }{S}_{\mathrm{R},\max }=10$ and 13 J/kg K obtained by a simple rotating of the single crystal within the $ab$ plane in the constant magnetic field 2 and 5 T, respectively. Large $\mathrm{\Delta }{S}_{\mathrm{R}}$ values with no hysteresis losses and rather wide working temperature spans imply that ${\text{KEr}\left({\mathrm{MoO}}_4\right)}_2$ may serve as a promising candidate for the implementation of a compact rotary magnetic cryorefrigerator.