Direct photoemission spectroscopy and electronic properties of in situ grown, strained high- Tc and related oxide films

• Published in: The Journal of physics and chemistry of solids Vol. 65; no. 8; pp. 1391 - 1395
• Main Authors: Abrecht, Mike, Ariosa, Daniel, Cloetta, Dominique, Vobornik, Dusan, Margaritondo, Giorgio, Pavuna, Davor
• Format: Journal Article Conference Proceeding
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2004; Elsevier
• Subjects: Clean metal, semiconductor, and insulator surfaces; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron and ion emission by liquids and solids; impact phenomena; Electronic structure; Exact sciences and technology; Photoemission and photoelectron spectra; Physics; Properties of type I and type II superconductors; Superconductivity; Photoelectron spectra; Inorganic compounds; Angular resolution; Brillouin zones; Transition element compounds; Oxides; Pulsed laser deposition; Electronic density of states; Cuprates; Thin films; Electronic structure; High-Tc superconductors; Fermi surface; Synchrotron radiation
• ISSN: 0022-3697; 1879-2553
• DOI: 10.1016/j.jpcs.2003.12.016

We have optimized laser ablation thin film deposition and transfer procedures within synchrotron vault, specifically to perform angle-integrated and angle-resolved photoemission spectroscopy (ARPES) on high- T c and related films without cleaving the samples. However, the chain-containing phases like YBCO-123 easily loose surface oxygen and do not exhibit stable Fermi edge, hence are not suitable for ARPES studies. Direct in situ ARPES studies on strained LSCO-214 films show striking strain effects on the electronic structure. The Fermi surface (FS) of LSCO evolves with doping, yet changes even more significantly with strain. The strain changes the FS topology from hole-like to electron-like, and causes band dispersion along k x and the Fermi level crossing before the Brillouin zone boundary, in sharp contrast to the ‘usual’ flat band remaining ≈30 meV below E F measured on unstrained samples. The associated reduction of the density of states does not diminish the superconductivity; T c is enhanced in all our strained samples. Implications for the evolving high- T c theory and studies of nano-engineered film heterostructures are briefly discussed.