We report measurements up to 85 Tesla of the upper critical fields $H_{c2}$($T$) on Ba${}_{1-x}$K${}_x$As${}_2$Fe${}_2$ single crystals and FeSe${}_{1-x}$Te${}_x$ films tuned by doping and strain. We observed an $H_{c2}$ enhancement by more than 25 T at low temperatures for the optimally doped Ba${}_{1-x}$K${}_x$As${}_2$Fe${}_2$ as compared to the previous measurements and extraordinarily high slopes of $d{H}_{c2}$/$\mathit{dT}$ $=$ 250–500 T/K near $T_c$ in FeSe${}_{1-x}$Te${}_x$, indicating almost-complete suppression of orbital pair breaking. Theoretical analysis of $H_{c2}$($T$) suggests an inhomogeneous Fulde-Ferrel-Larkin-Ovchinnikov state below 10K for $H//ab$ in the optimally doped Ba${}_{1-x}$K${}_x$As${}_2$Fe${}_2$ and below 3K for $H//c$ and 9K for $H//ab$ in FeSe${}_{1-x}$Te${}_x$. The analysis also shows that $H_{c2}$ in a multiband Fe-based superconductor can be significantly enhanced by doping and strain by shrinking and expanding different pockets of the Fermi surface, which can be more effective than the conventional way of increasing $H_{c2}$ by nonmagnetic impurities.

Anisotropy effects on flux pinning and flux flow are strongly effective in cuprate as well as iron-based superconductors due to their intrinsically layered crystallographic structure. However Fe(Se,Te) thin films grown on CaF₂ substrate result less anisotropic with respect to all the other iron based superconductors. We present the first study on the angular dependence of the flux flow instability, which occurs in the flux flow regime as a current driven transition to the normal state at the instability point (I*, V*) in the current-voltage characteristics. The voltage jumps are systematically investigated as a function of the temperature, the external magnetic field, and the angle between the field and the Fe(Se,Te) film. The scaling procedure based on the anisotropic Ginzburg-Landau approach is successfully applied to the observed angular dependence of the critical voltage V*. Anyway, we find out that Fe(Se,Te) represents the case study of a layered material characterized by a weak anisotropy of its static superconducting properties, but with an increased anisotropy in its vortex dynamics due to the predominant perpendicular component of the external applied magnetic field. Indeed, I* shows less sensitivity to angle variations, thus being promising for high field applications.

In the frame of the Next Generation Europe program, the EU program to boost after-COVID recovery, the Italian Minister of University and Research has funded a project called Innovative Research Infrastructure for applied Superconductivity (IRIS). New laboratories will be built or upgraded in six poles: Milan (hub of the infrastructure), Genoa, Frascati, Naples, Salerno, and Lecce, to carry out basic research on magnetism and superconducting materials, test of wires, tapes, and large current cables, superconducting magnets construction with advanced instrumentation, power tests of magnets, and a special facility for high current-high voltage superconducting lines. The program will be executed over three years and then will operate for at least 10 years. It includes two first demonstrators: one HTS magnet to be operated at 10–20 K and a superconducting line of 1 GW (40 kA–25 kV) about 140 m long. The demonstrators anticipate the main scope of the investment in the IRIS infrastructure: to support the use of superconductivity for improving sustainability by decreasing the energy consumption without compromising performance. This article describes the global IRIS project.

The origin of (ferro)magnetic ordering in transition metal doped ZnO is a still open question. For applications it is fundamental to establish if it arises from magnetically ordered impurity clusters embedded into the semiconducting matrix or if it originates from ordering of magnetic ions dilute into the host lattice. In this latter case, a reciprocal effect of the magnetic exchange on the charge carriers is expected, offering many possibilities for spintronics applications. In this paper we report on the relationship between magnetic properties and free charge density investigated by using Zinc oxide based field effect transistors, in which the charge carrier density is modulated by more than 4 order of magnitude, from 10¹⁶ to 10²⁰ e⁻/cm³. The magnetotransport properties are employed to probe the magnetic status of the channel both in pure and cobalt doped zinc oxide transistors. We find that it is widely possible to control the magnetic scattering rates by field effect. We believe that this finding is a consequence of the modulation of magnetization and carrier spin polarization by the electric field. The observed effects can be explained by the change in size of bound magnetic polarons that induces a percolation magnetic ordering in the sample.

In this paper, the feasibility of producing Fe(Se,Te) coated conductors on cost-effective, unbuffered Invar 36 substrates is studied. A suitable substrate with a sharp {001} texture and a misorientation angle lower than 10° was developed, and the possibility of growing epitaxial thin films without any buffer layer was demonstrated. It was also shown that the presence of a Fe(Se,Te) seed layer can improve the in- and out-of-plane orientation of the film. A high resolution scanning electron microscopy study was performed, and the absence of a superconducting transition has been attributed to Ni poisoning based on X-ray microanalysis.

At the present day, iron-based superconductors (IBS) can be considered as competitors of cuprates for the fabrication of su-perconducting cables for high field application in the presence of particle irradiation. In particular, it has been demonstrated that 11 IBS are very robust against proton irradiation. In this work, we analyze the effect of this kind of irradiation on the anisotropy of superconducting and pinning properties of Fe(Se,Te) thin films grown on CaF $^{2}$ . By electrical transport measurements, we evaluate the upper critical field as a function of the temperature and the pinning activation energy as function of the applied magnetic field, for different orientation between the material crystal structure and the field itself, in pristine and irradiated samples. The aim is to recognize if and how proton irradiation modifies the anisotropy of the material properties.