S. L. Prischepa

Interface transparency and proximity effect in Nb/Cu triple layers realized by sputtering and molecular beam epitaxy

We have investigated, in the framework of the proximity effect theory, the interface transparency T between Nb and Cu in the case of high quality Nb/Cu trilayers fabricated by molecular beam epitaxy (MBE) and sputtering deposition techniques. The obtained T values do not seem to be strongly influenced by the fabrication methods but more by the intrinsic properties of the two metals; a slightly higher value for T has even been deduced for the MBE prepared samples. The proximity effect in these samples has also been studied in the presence of an external magnetic field. In the parallel configuration a significant shift towards lower values of the 2D–3D crossover temperature has been observed for MBE samples, in good agreement with very recent theoretical predictions. In the perpendicular case a positive curvature of the temperature dependence of the upper critical field has been detected, which was less pronounced for sputtered samples. Both the effects have been observed only for trilayers with low Nb thickness (<600 A) which confirms the crucial influence of the interface transparency on the values of the upper critical field in such samples.

Critical currents of MgB 2 thin films deposited in situ by sputtering

We have measured the temperature and magnetic field dependencies of the critical current density J c (H,T) in MgB 2 thin films, in situ deposited by sputtering. Three-dimensional point like normal core pinning was evidenced by measurements of the magnetic dependence of the pinning forces independently from the superconducting and structural quality of the investigated films. The analysis of the experimental data in terms of the collective pinning model has pointed out the presence of a crossover magnetic field from a single vortex to a small vortex bundle pinning regime. A ΔT c pinning mechanism, i.e., a pinning associated with spatial fluctuations of the transition temperature, has been evidenced by the temperature dependence of this crossover field, in agreement with previous observations performed on MgB 2 bulk materials.

Interface transparency of Nb/Pd layered systems

Abstract.We have investigated, in the framework of proximity effect theory, the interface transparency

Manifestation of coherent magnetic anisotropy in a carbon nanotube matrix with low ferromagnetic nanoparticle content

{\cal T}

Properties of Bi2+xSr2−xCuO6+δ thin films obtained by MBE

of superconducting/normal metal layered systems which consist of Nb and high paramagnetic Pd deposited by dc magnetron sputtering. The obtained

Bi2Sr2CuO6+δ/ACuO2(A=Ca, Sr) superconducting multilayers obtained by Molecular Beam Epitaxy

{\cal T}

Disorder and vortex dynamics in high- superconductors

value is relatively high, as expected by theoretical arguments. This leads to a large value of the ratio

Nitrogen-doped twisted graphene grown on copper by atmospheric pressure CVD from a decane precursor

d_{s}^{cr}/ \xi_{s}

The influence of a submicrometre antidot array on the vortex topology and the pinning mechanism in layered superconductors

although Pd does not exhibit any magnetic ordering.

Superconducting nanowire quantum interference device based on Nb ultrathin films deposited on self-assembled porous Si templates

The influence of the magnetic medium can lead to peculiar interaction between ferromagnetic nanoparticles (NPs). Most research in this area involves analysis of the interplay between magnetic anisotropy and exchange coupling. Increasing the average interparticle distance leads to the dominant role of the random magnetic anisotropy. Here we study the interparticle interaction in a carbon nanotube (CNT) matrix with low ferromagnetic NP content. Samples were synthesized by floating catalyst chemical vapor deposition. We found that below some critical NP concentration, when NPs are intercalated only inside CNTs, and at low temperatures, the extended magnetic order, of up to 150 nm, presents in our samples. It is shown by analyzing the correlation functions of the magnetic anisotropy axes that the extended order is not simply due to random anisotropy but is associated with the coherent magnetic anisotropy, which is strengthened by the CNT alignment. With increasing temperature the extended magnetic order is lost. Above the critical NP concentration, when NPs start to be intercalated not only into inner CNT channels, but also outside CNTs, the coherent anisotropy weakens and the exchange coupling dominates in the whole temperature range. We can make a connection with the various correlation functions using the generalized expression for the law of the approach to saturation and show that these different correlation functions reflect the peculiarities in the interparticle interaction inside CNTs. Moreover, we can extract such important micromagnetic parameters like the exchange field, local fields of random and coherent anisotropies, as well as their temperature and NP concentration dependencies.