Photoemission spectromicroscopy study of a Bi 2Sr 2CaCu 2O8+x single crystal

Using photoemission spectromicroscopy at sub-micron lateral resolution we studied two superconductor systems of high fundamental and practical importance, such as Bi 2Sr 2CaCu 2O and MgB 2. Our findings demonstrate the importance of considering, for this class of Systems, the possible presence of spatial inhomogeneities in interpreting the results of conventional photoemission experiments, which typically probe an area of the order of 1 mm 2. In particular, in the case of MgB 2, we report a measured density of states directly comparable to the theoretical predictions, thus rejecting the daim for the existence of strong correlation effects proposed by previous spatially averaged measurements.