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Systematic studies of (magneto)transport, structural and electronic properties of ultra-thin films of high-T-c cuprates and related layered oxides

Properties of ultra-thin films are different from their single crystal counterparts due to the presence of (substrate induced) strain, different degree and type of (growth induced) disorder and different average doping (distribution of oxygen vacancies, for example). Here we briefly summarize main results on ultra-thin (99 --> 1 unit cell (UC)) superconducting oxide films grown by laser ablation. Systematic studies show that BSCCO-2212, 2201, 2223, and LSCO-214 exhibit conductor-like Fermi edge, whereas materials containing "chains" (like YBCO-123) are prone to very rapid surface degradation, possibly related to critical oxygen loss at the outermost layers. Combined with X-ray analysis we have determined that BSCCO-2212 films undergo a structural phase transition at a nominal thickness of approximately 1 UC, converting the precursor Bi2O2.33 highly coherent ultra-thin film into the Bi-2212 structure. Our most recent angle resolved photoemission spectroscopy (ARPES) measurements on strained superconducting LSCO-214 thin films (with T-c of up to 44 K) are also discussed. For the first time the dispersion in ARPES spectra measured on such in situ grown strained LSCO film is shown. The relevance of these new results is briefly discussed. (C) 2002 Published by Elsevier Science B.V.

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