ISSN:
1432-0630
Schlagwort(e):
PACS: 73.20.At; 73.40.Gk; 74.70.Vy
Quelle:
Springer Online Journal Archives 1860-2000
Thema:
Maschinenbau
,
Physik
Notizen:
Abstract. The low-energy electronic structure of a c-axis SrxAyCuO2 (A is alkaline earth cation, x+y≦1, hole- and electron-doped infinite layer) thin film, grown by laser-molecular-beam epitaxy on a SrTiO3 (001) substrate, has been studied using ultrahigh-vacuum scanning tunneling microscopy/spectroscopy. Images have been obtained for co-deposited SrxAyCuO2 thin films, which show the surface consisting of flat terraces separated by steps that are unit cell high. Tunneling spectra of undoped Sr0.3Ca0.7CuO2 indicate a wide band gap of 1.8 eV which is consistent with the charge transfer gap. Hole-doped Sr0.85CuO2 shows in-gap states appearing at both the valence and conduction band edges. In contrast, for the electron-doped Sr0.9La0.1CuO2, in-gap states appear predominantly above the Fermi level, and the spectral shape becomes asymmetric around the Fermi level. When these two systems are compared, barrier-height measurements reveal that there is no apparent shift of the Fermi level measured from the vacuum level. This suggests that the framework of the rigid-band picture might break down implying a strongly correlated electron system.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1007/s003390050961
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