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The magneto- mechanical behaviour of structural steel specimens stressed up to a plastic deformation stage using a high- Tc scanning SQUID ( superconducting quantum interference device) microscope is investigated. The correlation between the gradient of the normal component of the magnetization and dislocation density, before the crack initiation, is carried out. The capability of scanning SQUID microscopy to detect the residual magnetization, due to the tensile stress, with a non- invasive technique is reported.

In this work an eddy current technique based on a HTS-SQUID (superconducting quantum interference device) is used to evaluate the relation between the magnetic field response and the damage process of one of the most promising fibre metallic laminates known as GLARE®. In particular the magnetic field response due to impact loading at energies ranging from 5 to 36 J has been detected. The magnetic field signal from GLARE® specimens in the presence of mechanical damaging is discussed according to a simple electromagnetic model.

The main advantage of using SQUIDs in NDE is its unrivalled magnetic sensitivity down to very low frequencies, which allows the detection of weak magnetic fields due to defects also in very low electrical conductive materials like CFRP, commonly used in aerospace structures. In this work the fatigue damage evaluation on CFRP laminates, cross-ply or quasi-isotropic, in real-time during quasi-static loading is monitored. The material responses are detected by using an Eddy Current technique with HTS dc SQUID magnetometer.

The interest in magnetometry for eddy-current non-destructive testing, e.g. of planar conductive structures encountered in the aircraft industry, using high-temperature superconducting quantum interference devices (SQUIDs) is primarily due to their high sensitivity to magnetic flux even at very low frequencies. Here it is shown how theoretical, numerical and measurement machineries are combined to get reasonable synthetic and experimental data and to reach a good understanding of the interaction of diffusive wavefields with a damaged non-magnetic metal plate (as a first step towards the retrieval of pertinent features of the defects). The measurement modalities are considered first. It is illustrated in some detail how laboratory-controlled experiments are performed by a SQUID-based probe displaced above artificially damaged plates. Experimental data are then confronted with simulation results in order to evaluate the accuracy and reliability of this measurement system. Simulations are carried out by a computationally fast vector volume integral method dedicated to a planar layering affected by a volumetric defect, which involves the construction of the dyadic Green system of the layering.

Femtosecond spectroscopy has been used to investigate the quasi-particle relaxation times in nearly optimally doped Fe-based superconductors FeSe 0.5Te0.5 and optimally doped Ba-122 thin films growth on a Fe buffer layer. Experimental results concerning the temperature dependence of the relaxation time of such pnictides both in the superconducting state are now presented and discussed. Modelling the T-dependence of relaxation times an estimation of both electron-phonon constant and superconducting energy gap in the excitation spectrum of both Fe(Se,Te) and Ba-122 compounds is obtained.

We present characterization of Ba(Fe1-x Cox) 2As2 thin film using a magneto-optical Kerr effect setup based on photoelastic modulation. The magneto optical technique has been used to analyse the thickness and the temperature dependence of the magnetic properties of epitaxial Ba(Fe1-x Cox)2As2/Fe thin films grown on MgO substrate. The first harmonics, of the reflected laser beam intensity from pnictide thin films is compared with a reference Fe thin film. The hysteretic loops of such samples at room temperature and at 5K are presented.

The correlation between electrical conductivity and magnetic field response, due to multi-walled carbon nanotubes' (MWCNTs) distribution within the polymer matrix, has been demonstrated using a contactless and non-destructive technique. Multi-walled carbon nanotubes, both buckypaper and reinforced epoxy matrix specimens with different nanotube percentages, have been inspected using the eddy current technique based on an HTc SQUID magnetometer. The SQUID magnetic field response, due to the nanotube distribution, has been compared with the thermographic technique results. Moreover, the electrical conductivity of nanotube-reinforced composites and buckypaper has been carried out by using the Van der Pauw method.