Comparison of Magneto-Optical Imaging with Other Local Magnetic Probes

Abstract

Over the past decade the development and refinement of a range of low temperature local magnetic probes has greatly advanced our understanding of vortex matter in type II superconductors. Many complementary techniques are now capable of imaging discrete vortices over quite wide ranges of H-T phase space, yielding very direct information regarding vortex structures and dynamics, and the relationship with other sample properties e.g. shape, microstructure and defect density. A detailed review of local magnetic probes will be presented here including Lorentz microscopy, magnetic force microscopy, scanning Hall probe microscopy, magneto-optical imaging (MOI) and scanning SQUID microscopy. In each case the principles underpinning the technique will be briefly reviewed along with the factors that limit magnetic field, spatial and temporal resolution. In addition the capabilities will be compared and contrasted with those of state-of-the-art MOI where relevant. A range of examples is described emphasising applications in the area of high temperature superconductors. Finally the ways in which the existing techniques can be expected to develop over the next few years will be discussed and new approaches that seem likely to be successful described.