Probing the current-phase relation in Josephson point-contact junctions between [Formula: see text]In[Formula: see text] and [Formula: see text]K[Formula: see text](FeAs)[Formula: see text] superconductors.

The Josephson effect in point contacts between an "ordinary" superconductor [Formula: see text]In[Formula: see text] ([Formula: see text]) and single crystals of the Fe-based superconductor Ba[Formula: see text]K[Formula: see text](FeAs)[Formula: see text] ([Formula: see text]), was investigated. In order to shed light on the order parameter symmetry of Ba[Formula: see text]K[Formula: see text](FeAs)[Formula: see text], the dependence of the Josephson supercurrent [Formula: see text] on the temperature and on [Formula: see text] with [Formula: see text] was studied. The dependencies of the critical current on temperature [Formula: see text] and of the amplitudes of the first current steps of the current-voltage characteristic [Formula: see text] [Formula: see text] on the power of microwave radiation with frequency [Formula: see text] were measured.

The 2021 room-temperature superconductivity roadmap.

Designing materials with advanced functionalities is the main focus of contemporary solid-state physics and chemistry. Research efforts worldwide are funneled into a few high-end goals, one of the oldest, and most fascinating of which is the search for an ambient temperature superconductor (A-SC). The reason is clear: superconductivity at ambient conditions implies being able to handle, measure and access a single, coherent, macroscopic quantum mechanical state without the limitations associated with cryogenics and pressurization.

Directed Self-Assembly of Polystyrene Nanospheres by Direct Laser-Writing Lithography.

In this work, we performed a systematic study on the effect of the geometry of pre-patterned templates and spin-coating conditions on the self-assembling process of colloidal nanospheres. To achieve this goal, large-scale templates, with different size and shape, were generated by direct laser-writer lithography over square millimetre areas. When deposited over patterned templates, the ordering dynamics of the self-assembled nanospheres exhibits an inverse trend with respect to that observed for the maximisation of the correlation length ξ on a flat surface.

Chemical-Vapor-Deposited Graphene as a Thermally Conducting Coating.

We performed scanning thermal microscopy measurements on single layers of chemical-vapor-deposited (CVD) graphene supported by different substrates, namely, SiO, AlO, and PET using a double-scan technique to remove the contribution to the heat flux through the air and the cantilever. Then, by adopting a simple lumped-elements model, we developed a new method that allows determining, through a multistep numerical analysis, the equivalent thermal properties of thermally conductive coatings of nanometric thickness. In this specific case we found that our CVD graphene is "thermally equivalent", for heat injection perpendicular to the graphene planes, to a coating material of conductivity = 2.

Mapping multi-valley Lifshitz transitions induced by field-effect doping in strained MoS nanolayers.

Gate-induced superconductivity at the surface of nanolayers of semiconducting transition metal dichalcogenides (TMDs) has attracted a lot of attention in recent years, thanks to the sizeable transition temperature, robustness against in-plane magnetic fields beyond the Pauli limit, and hints to a non-conventional nature of the pairing. A key information necessary to unveil its microscopic origin is the geometry of the Fermi surface hosting the Cooper pairs as a function of field-effect doping, which is dictated by the filling of the inequivalent valleys at the K/K[Formula: see text] and Q/Q[Formula: see text] points of the Brillouin zone. Here, we achieve this by combining density functional theory calculations of the bandstructure with transport measurements on ion-gated 2H-MoS nanolayers.

Fermi-Surface Topological Phase Transition and Horizontal Order-Parameter Nodes in CaFe2As2 Under Pressure.

Iron-based compounds (IBS) display a surprising variety of superconducting properties that seems to arise from the strong sensitivity of these systems to tiny details of the lattice structure. In this respect, systems that become superconducting under pressure, like CaFe2As2, are of particular interest. Here we report on the first directional point-contact Andreev-reflection spectroscopy (PCARS) measurements on CaFe2As2 crystals under quasi-hydrostatic pressure, and on the interpretation of the results using a 3D model for Andreev reflection combined with ab-initio calculations of the Fermi surface (within the density functional theory) and of the order parameter symmetry (within a random-phase-approximation approach in a ten-orbital model).

Temperature dependence of electric transport in few-layer graphene under large charge doping induced by electrochemical gating.

The temperature dependence of electric transport properties of single-layer and few-layer graphene at large charge doping is of great interest both for the study of the scattering processes dominating the conductivity at different temperatures and in view of the theoretically predicted possibility to reach the superconducting state in such extreme conditions. Here we present the results obtained in 3-, 4- and 5-layer graphene devices down to 3.5 K, where a large surface charge density up to about 6.

Large conductance modulation of gold thin films by huge charge injection via electrochemical gating.

By using an electrochemical gating technique with a new combination of polymer and electrolyte, we were able to inject surface charge densities n(2D) as high as 3.5×10(15)  e/cm(2) in gold films and to observe large relative variations in the film resistance, ΔR/R', up to 10% at low temperature. ΔR/R' is a linear function of n(2D)-as expected within a free-electron model-if the film is thick enough (≥25  nm); otherwise, a tendency to saturation due to size effects is observed.

Multigap superconductivity and strong electron-boson coupling in Fe-based superconductors: a point-contact Andreev-reflection study of Ba(Fe(1-x)Co(x))2As2 single crystals.

Directional point-contact Andreev-reflection measurements in Ba(Fe(1-x)Co(x))2As2 single crystals (T(c) = 24.5 K) indicate the presence of two superconducting gaps with no line nodes on the Fermi surface. The point-contact Andreev-reflection spectra also feature additional structures related to the electron-boson interaction, from which the characteristic boson energy Ω(b)(T) is obtained, very similar to the spin-resonance energy observed in neutron scattering experiments.

Thermal and electronic properties of macroscopic multi-walled carbon nanotubes blocks.

Massive carpets of well packed, vertically aligned and very long multiwall carbon nanotubes were synthesized by an efficient thermal Chemical Vapour Deposition process. Electrical properties of the material were evaluated, both in terms of "global" characteristics (bulk resistivity) and in terms of "local" properties (Scanning Tunnel Spectroscopy measurements) for as-grown and annealed at different temperatures samples. The behaviour of bulk resistivity as a function of temperature was evaluated in the range 3-300 K, with a four-probe technique.

Evidence for gap anisotropy in CaC6 from directional point-contact spectroscopy.

We present the first results of directional point-contact spectroscopy in high-quality CaC6 samples both along the ab plane and in the c-axis direction. The superconducting order parameter Delta(0), obtained by fitting the Andreev-reflection (AR) conductance curves at temperatures down to 400 mK with the single-band 3D Blonder-Tinkham-Klapwijk model, presents two different distributions in the two directions of the main current injection, peaked at 1.35 and 1.

Effect of magnetic impurities in a two-band superconductor: a point-contact study of mn-substituted single crystals.

We present the first results of directional point-contact measurements in Mg1-xMnxB2 single crystals, with x up to 0.015 and bulk Tc down to 13.3 K.

Direct evidence for two-band superconductivity in MgB2 single crystals from directional point-contact spectroscopy in magnetic fields.

We present the results of the first directional point-contact spectroscopy experiments in high-quality MgB2 single crystals. Because of the directionality of the current injection into the samples, the application of a magnetic field allowed us to separate the contributions of the sigma and pi bands to the total conductance of our point contacts. By using this technique, we were able to obtain the temperature dependency of each gap independent of the other.

Josephson effect in MgB(2) break junctions.

We present the first observation of the dc and ac Josephson effect in MgB(2) break junctions. The junctions, obtained at 4.2 K in high-quality, high-density polycrystalline metallic MgB(2) samples, show a nonhysteretic dc Josephson effect.

Automatic model selection for the 'best localization' of cardiac sources.

In the present paper a simulation study on the influence of noise and source model on the accuracy of localization of the sources of biomagnetic fields is presented. Applying a statistical analysis (F test) to the localization results obtained by various models on the simulated maps calculated using different theoretical sources and different noise levels we were able to define a 'best localization' (BL) method. It allows an automatic determination of the particular source model able to represent in the best statistical way a specific field distribution obtaining the best source localization for that distribution.

Inverse problem solution in cardiomagnetism using a current multipole expansion of the primary sources.

The equivalent current dipole (ECD) model is only the first-order approximation in modelling the primary sources of the magnetic field of the heart. From the experimental point of view this fact is particularly evident during the onset of ventricular depolarisation. In this paper we have tried to explain the departures of the experimental maps from the dipolar pattern in terms of the second-order component of the current multipole expansion for the primary source density.