We performed zero and transverse field muon spin rotation experiments on a large number of ${\mathrm{Y}\mathrm{B}\mathrm{a}}_2{\mathrm{C}\mathrm{u}}_3{\mathrm{O}}_{6+x}$ samples. We detect the coexistence of antiferromagnetic (AF) short range magnetism with superconductivity below $T_f\lesssim 10\mathrm{K}$ in compositions $0.37\lesssim x\lesssim 0.39$. Most muons experience local AF fields, even when a SQUID detects a full superconducting volume fraction, which points to a local minimal interference organization of short AF stripes embedded in the superconductor. A detailed phase diagram is produced and the consequences of the minimal interference are discussed.

The aim of the present work is to highlight the unique role of anilato-ligands, derivatives of the 2,5-dioxy-1,4-benzoquinone framework containing various substituents at the 3 and 6 positions (X = H, Cl, Br, I, CN, etc.), in engineering a great variety of new materials showing peculiar magnetic and/or conducting properties. Homoleptic anilato-based molecular building blocks and related materials will be discussed. Selected examples of such materials, spanning from graphene-related layered magnetic materials to intercalated supramolecular arrays, ferromagnetic 3D monometallic lanthanoid assemblies, multifunctional materials with coexistence of magnetic/conducting properties and/or chirality and multifunctional metal-organic frameworks (MOFs) will be discussed herein. The influence of (i) the electronic nature of the X substituents and (ii) intermolecular interactions i.e., H-Bonding, Halogen-Bonding, π-π stacking and dipolar interactions, on the physical properties of the resulting material will be also highlighted. A combined structural/physical properties analysis will be reported to provide an effective tool for designing novel anilate-based supramolecular architectures showing improved and/or novel physical properties. The role of the molecular approach in this context is pointed out as well, since it enables the chemical design of the molecular building blocks being suitable for self-assembly to form supramolecular structures with the desired interactions and physical properties.

Magnetic properties of iron oxide nanoparticles with spinel structure are strictly related to a complex interplay between cationic distribution and the presence of a non-collinear spin structure (spin canting). With the aim to gain better insight into the effect of the magnetic structure on magnetic properties, in this paper we investigated a family of small crystalline ferrite nanoparticles of the formula Co_xNi_1−xFe₂O₄ (0 ≤ x ≤ 1) having equal size (≈4.5 nm) and spherical-like shape. The field dependence of magnetization at low temperatures indicated a clear increase of magnetocrystalline anisotropy and saturation magnetization (higher than the bulk value for CoFe₂O₄: ∼130 A m² kg⁻¹) with the increase of cobalt content. The magnetic structure of nanoparticles has been investigated by Mössbauer spectroscopy under an intense magnetic field (8 T) at a low temperature (10 K). The magnetic properties have been explained in terms of an evolution of the magnetic structure with the increase of cobalt content. In addition a direct correlation between cationic distribution and spin canting has been proposed, explaining the presence of a noncollinear spin structure in terms of superexchange interaction energy produced by the average cationic distribution and vacancies in the spinel structure.

The structural and magnetic properties of two Fe₂O₃–SiO₂ nanocomposites, containing respectively 16.9 and 28.5 wt.% Fe₂O₃, were investigated. The samples were synthetized by a sol–gel method, using ethylene glycol as a solvent, and heating the gels gradually to 900°C. The procedure allowed us to obtain γ-Fe₂O₃ nanoparticles homogeneously dispersed in the amorphous silica matrix. The particles have a narrow size distribution and mean sizes from 3 to 6 nm depending on the iron oxide content. The magnetic properties of the samples were investigated by static and dynamic susceptibility measurements. All the samples showed superparamagnetic behaviour. The superparamagnetic relaxation was investigated also by Mössbauer spectroscopy. Hysteresis loops were measured at 2.5 K and both samples showed high values of coercive field. The role of magnetic interparticle interactions on the magnetic properties is discussed.