We investigated the magnetic properties of the antiferromagnetic (AFM) topological insulator MnBi${}_2$Te${}_4$ with a partial substitution of Mn atoms by non-magnetic elements (A${}^{\mathrm{IV}}$ = Ge, Pb, Sn). Samples with various element concentrations (10–80%) were studied using SQUID magnetometry. The results demonstrate that, for all substitutes the type of magnetic ordering remains AFM, while the Néel temperature (T${}_{\mathrm{N}}$) and spin-flop transition field (H${}_{\mathrm{SF}}$) decrease with an increasing A${}^{\mathrm{IV}}$ = Ge, Pb, Sn concentration. The rate of decrease varies among the elements, being highest for Pb, followed by Sn and Ge. This behavior is attributed to the combined effects of the magnetic dilution and lattice parameter increase on magnetic properties, most prominent in (Mn${}_{1-x}$Pb${}_x$)Bi${}_2$Te${}_4$. Besides this, the linear approximation of the experimental data of T${}_{\mathrm{N}}$ and H${}_{\mathrm{SF}}$ suggests higher magnetic parameters for pure MnBi${}_2$Te${}_4$ than observed experimentally, indicating the possibility of their non-monotonic variation at low concentrations and the potential for enhancing magnetic properties through doping MnBi${}_2$Te${}_4$ with small amounts of nonmagnetic impurities. Notably, the (Mn${}_{1-x}$Pb${}_x$)Bi${}_2$Te${}_4$ sample with 10% Pb substitution indeed exhibits increased magnetic parameters, which is also validated by local-probe analyses using ARPES. Our findings shed light on tailoring the magnetic behavior of MnBi${}_2$Te${}_4$-based materials, offering insights into the potential applications in device technologies.

The critical exponent of the correlation length ν = 1.51 ± 0.25 and critical size d₀ = 1.2 ± 0.6 nm for the dipole ferromagnet DyF₃ has been determined experimentally by the finite-size-scalingt heory for the first time.

The magnetic properties of DyF₃ powders with a particle size of 16 nm–7 μm were studied.

For applications of nanolattices in low-temperature nanoelectronics, the inter-unit space can be filled with superconducting metallic alloys. However, superconductivity under nanoconfinement is expected to be strongly affected by size-effects and other factors. We studied the magnetic properties and structure of the Ga-Sn eutectic alloy within regular nanopores of an opal template, to understand the specifics of the alloy superconductivity. Two superconducting transitions were observed, in contrast to the bulk alloy. The transitions were ascribed to the segregates with the structures of tetragonal tin and a particular gallium polymorph. The superconducting-phase diagram was constructed, which demonstrated crossovers from the positive- to the common negative-curvature of the upper critical-field lines. Hysteresis was found between the susceptibilities obtained at cooling and warming in the applied magnetic field.