MgB 2 thin films were deposited using pulsed laser deposition (PLD) and ex situ annealing in Mg atmosphere. The films presented critical temperatures up to 36 K and turned out to be preferentially c-oriented both on Al 2 O 3 (r-cut) and MgO(100) substrates. Synchrotron analyses also gave some indications of in-plane texturing. The films exhibit very fine grain size (1200 Å in the basal plane and 100 Å along the c-axis) but the general resistivity behaviour and the remarkable extension of the irreversible region confirm that the grains' boundaries are not barriers for supercurrents. Upper critical field measurements with the magnetic field perpendicular and parallel with respect to the film surface evidenced a field anisotropy ratio of 1.8. The H c2 values are considerably higher with respect to the bulk ones, namely when the field lies in the basal plane, and the field-temperature phase diagram for the two magnetic field orientations suggest the possibility of strongly enhancing the pinning region by means of texturing.

Superconducting thin films of MgB 2 were deposited by Pulsed Laser Deposition on magnesium oxide and sapphire substrates. Samples grown at 450ºC in an argon buffer pressure of about 10 -2 mbar by using a magnesium enriched target resulted to be superconducting with a transition temperature of about 25 K. Film deposited from a MgB 2 sintered pellet target in ultra high vacuum conditions showed poor metallic or weak semiconducting behavior and they became superconducting only after an ex-situ annealing in Mg vapor atmosphere. Up to now, no difference in the superconducting properties of the films obtained by these two procedures has been evidenced.The recent outstanding discovery of 40K superconductivity in MgB 2 [1, 2] is a breakthrough that stimulated a worldwide excitement in the scientific community renewing the interest on superconductivity. This material exhibits a lot of intriguing properties: it is the compound with the highest T c among non-oxides materials and first reports indicate a phonon mediated mechanism for the superconductivity making MgB 2 also the BCS materials with the highest T C [3]. Furthermore, the grains boundaries have not dramatic effects on the critical current densities, being of its coherence length longer than those of HTSC. The reported properties, the very simple structure and the commercial availability of this material make MgB 2 a favorite candidate for large scale and electronic applications and suggest the possibility of further progress in technology based on superconducting materials. The main limitation for the application seems to be related to the considerable small value of the irreversibility field (about 7 Tesla at liquid helium temperature) [4]. High quality epitaxial thin film are needed to implement a new class of electronic devices. Actually, thin film deposition of this material is a quite difficult task due to the high volatility of Mg, so that MgB 2 growth seems impossible in vacuum conditions. This necessity imposes severe restrictions on deposition systems and, up to now, superconducting thin films have been produced only via ex-situ annealing in magnesium atmosphere [5,6]. Very recently, an in situ annealing has been proposed [7] to react, after the deposition, stoichiometric or Mg rich mixture of magnesium and

We explored the feasibility of employing strontium titanate (SrTiO3) as semiconducting material in field-effect metal–insulator–semiconductor epitaxial heterostructures. This idea was suggested by the observation of a dramatic effect of the oxygen deficiency on SrTiO3−δ transport properties, which brings about metallic behavior with low-temperature mobility values comparable with those commonly found for silicon. By pulsed-laser deposition, we realized patterned field-effect devices, showing a resistance enhancement up to 90%. This promising result could open perspectives for crystalline-oxide electronics.

We report the demonstration of dc and ac Josephson effects in Nb/Al2O3/Al/MgB2 thin-film heterostructure. The heterostructure exhibits moderately hysteretic current–voltage characteristic with a dc Josephson current branch and regular microwave-induced Shapiro steps. From conductance spectrum, a gap of about 2 meV at 7.7 K is estimated for the proximized surface of MgB2 electrode.

Thin films of the intermetallic superconducting compound LuNi2B2C have been prepared by pulsed laser ablation, and different deposition parameters (substrate temperature, target-substrate distance, laser beam energy density and thickness) have been the subject of extensive studies to optimize growth. The best samples show electrical properties similar to those of single crystals (Tc = 16.4 K, ΔTc = 0.3 K, RRR = 13), are strongly c-axis-oriented, and present a high density of in-plane-oriented surface structures. This in-plane texturing is found only in films some thousands of ångström thick, while if the thickness is reduced below 1000-1500 Å the samples are very flat, but there is no evidence of in-plane texturing.