Imaging of Quantum Mechanical Effects in Superconductors by Means of Polarized Neutron Radiography

Polarization measurements in neutron imaging

“…While on a first glance the information content with respect to quantitative analyses appears limited, the continuous nature of magnetic fields and the spatial resolution of the data pro vide a context that allows for the extraction of a large variety of information despite the named limitations. This has been demonstrated and exploited in a number of applications so far [1,[8][9][10][11][12][13][14][15][16][17][18][19][20][21]. In particular, two and threedimensional data of that form provide a critical basis for modeling in order to retrieve field distributions as has been applied, for example, to the inter pretation of measurements of trapped fields in superconducting materials [1,17,18], but also to electric current observations [9].…”

“…This has been demonstrated and exploited in a number of applications so far [1,[8][9][10][11][12][13][14][15][16][17][18][19][20][21]. In particular, two and threedimensional data of that form provide a critical basis for modeling in order to retrieve field distributions as has been applied, for example, to the inter pretation of measurements of trapped fields in superconducting materials [1,17,18], but also to electric current observations [9].…”

“…Therefore, the potential of modeling systems and discrete measurements utilizing all a priori information on samples that are available provides an attractive alternative. While sev eral attempts have been reported [17][18][19][20][21], the approach and techniques are yet in an early stage of development; in par ticular, the uniqueness of modeling solutions describing an isolated measurement will have to be considered carefully. However, the principal tools of forward modeling are avail able and have been developed in a range of contexts through out the development of polarized imaging methods.…”

“…While some realspace obser vations of magnetic fields and structures have been reported earlier based on diffraction, phase, and refraction effects [2][3][4][5][6][7], the corresponding techniques suffered from low efficiency and did not lead to extensive utilization. Eventually, based on the work of Kardjilov et al [1], it was demonstrated that the utiliza tion of polarized neutrons in imaging allows the visualization of magnetic structures, fields, and phenomena even with basic spin polarization and analyzer components added to dedicated highflux imaging beamlines [1,[8][9][10][11][12][13][14][15][16][17][18][19][20][21]. The main difference to earlier approaches is the attempt to keep track of the neutron polarization vector while maintaining the spatial resolution capability in the intense transmitted beam.…”

High-resolution neutron depolarization microscopy of the ferromagnetic transitions in Ni3Al and HgCr2Se4 under pressure

“…When a neutron non-adiabatically enters a magnetic field, its magnetic moment undergoes Larmor precession. Changes in the polarization state of the transmitted neutron beam can probe the magnetic domain distribution inside a ferromagnet [32,28,33], magnetic islands in spin glasses [34,35,4], or the Meissner field outside a superconductor [36,37,38].…”