J. Phys. IV France 104 (2003) 487
DOI: 10.1051/jp4:20030128

Photoemission spectromicroscopy study of a Bi ₂Sr ₂CaCu ₂O single crystal

M. Bertolo¹, A. Bianco¹, G. Cautero¹, A. Goldoni¹, R. Larciprete¹, S. La Rosa¹, S. Lizzit¹, A.A. Zakharov², I. Lindau³, I. Vobornik⁴ and R. Yoshizaki<sup>5

1</sup>  Sincrotrone Trieste, S.S. 14 km 163.5 in Area Science Park, 34012 Basovizza (Trieste), Italy
²  Max-Laboratory, Lund University, P.O. Box 118, 22100 Lund, Sweden
³  Department of Synchrotron Radiation Research, Lund University, P.O. Box 118, 22100 Lund, Sweden
⁴  Laboratorio Nazionale TASC-INFM, S.S. 14 km 163.5, 34012 Basovizza (Trieste), Italy
⁵  Institute of Applied Physics and Cryogenic Center, University of Tsukuba, Tsukuba, Ibaraki 305, Japan

Abstract
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.

© EDP Sciences 2003