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.

Many current research efforts in strongly correlated systems focus on the interplay between magnetism and superconductivity. Here we report on coexistence of both cooperative ordered states in recently discovered stoichiometric and fully inversion symmetric heavy fermion compound Ce₃PdIn₁₁ at ambient pressure. Thermodynamic and transport measurements reveal two successive magnetic transitions at T₁ = 1.67 K and T_N = 1.53 K into antiferromagnetic type of ordered states. Below T_c = 0.42 K the compound enters a superconducting state. The large initial slope of dB_c2/dT ≈ – 8.6 T/K indicates that heavy quasiparticles form the Cooper pairs. The origin of the two magnetic transitions and the coexistence of magnetism and superconductivity is briefly discussed in the context of the coexistence of the two inequivalent Ce-sublattices in the unit cell of Ce₃PdIn₁₁ with different Kondo couplings to the conduction electrons.

Theoretical and experimental studies of a quasi-two-dimensional quantum antiferromagnet $\text{Cu}(\mathrm{en}){\left({\mathrm{H}}_2\mathrm{O}\right)}_2{\mathrm{SO}}_4$ $\left(\mathrm{en}={\mathrm{C}}_2{\mathrm{H}}_8{\mathrm{N}}_2\right)$ were performed. ab initio calculations of exchange interactions confirmed that the system represents a realization of a spatially anisotropic zigzag square lattice. Corresponding quantum Monte Carlo calculations of thermodynamic quantities were realized and the results were applied in the analysis of experimental susceptibility, magnetization, and specific heat studied at temperatures ranging from nominally 300 mK up to 8 K and magnetic fields up to 14 T. The analysis of experimental results provided the estimates of intralayer exchange couplings, $J/k_B=3.5\pm 0.2$ K and $J^{\prime }=0.35J$. Theoretical analysis of spin symmetries in $\text{Cu}(\mathrm{en}){\left({\mathrm{H}}_2\mathrm{O}\right)}_2{\mathrm{SO}}_4$ structure predicted the presence of symmetric exchange anisotropies (out-of plane and in-plane spin anisotropy) and a spin-flop transition within the easy plane induced by the magnetic field applied along the easy axis. Isothermal magnetization measurements indicated the expected transition in the field 200 mT applied along the $b$ axis which was finally identified as the easy axis lying within the easy plane $bc$. Magnetic phase diagrams with saturation fields about 6.5 T show nearly identical behavior in all studied directions. Differences appear only in weak magnetic fields as a result of the presence of weak exchange anisotropies $\approx {10}^{-3}J$. The present analysis suggests that $\text{Cu}(\mathrm{en}){\left({\mathrm{H}}_2\mathrm{O}\right)}_2{\mathrm{SO}}_4$ can be a model system for exploring the interplay of quantum fluctuations, exchange anisotropies, and magnetic field in the two-dimensional lattice space.

We present a first-principles study of the electronic, magnetic, and transport properties of the topological insulator ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ doped with Mn atoms in substitutional $\left({\mathrm{Mn}}_{\mathrm{Bi}}\right)$ and interstitial van der Waals gap positions $\left({\mathrm{Mn}}_i\right)$, which act as acceptors and donors, respectively. The effect of native ${\mathrm{Bi}}_{\mathrm{Te}}$- and ${\mathrm{Te}}_{\mathrm{Bi}}$-antisite defects and their influence on calculated electronic transport properties is also investigated. We have studied four models representing typical cases, namely, (i) ${\mathrm{Bi}}_2{\mathrm{Te}}_3$ with and without native defects, (ii) ${\mathrm{Mn}}_{\mathrm{Bi}}$ defects with and without native defects, (iii) the same, but for ${\mathrm{Mn}}_i$ defects, and (iv) the combined presence of ${\mathrm{Mn}}_{\mathrm{Bi}}$ and ${\mathrm{Mn}}_i$. It has been found that lattice relaxations around ${\mathrm{Mn}}_{\mathrm{Bi}}$ defects play an important role for both magnetic and transport properties. The resistivity is strongly influenced by the amount of carriers, their type, and by the relative positions of the Mn-impurity energy levels and the Fermi energy. Our results suggest strategies to tune bulk resistivities and also clarify the location of Mn atoms in samples. Calculations indicate that at least two of the considered defects have to be present simultaneously in order to explain the experimental observations, and the role of interstitials may be more important than expected.