Occupied density of states in MgB2 revealed by photoemission microscopy

Using photoemission microscopy at submicron lateral resolution, we measured the occupied density of states in MgB2 single crystalline grains from commercial MgB2 powder. This experiment provided a reliable measurement of the integrated density of states in MgB2 directly comparable to the theoretical predictions. According to the conventional metallic nature of MgB2, with weak electron-electron correlation effects, we observe a close overall agreement between our photoemission valence-band spectrum and the calculated density of states. This is further supported by the analysis of the loss features in the B 1s photoemission spectrum. We also report evidence of a quick surface degradation due to the exposure to the synchrotron radiation beam.