Polar catastrophe and electronic reconstructions at the LaAlO3-SrTiO3 interface: evidence from optical second harmonic generation - Condensed Matter > Materials ScienceReport as inadecuate




Polar catastrophe and electronic reconstructions at the LaAlO3-SrTiO3 interface: evidence from optical second harmonic generation - Condensed Matter > Materials Science - Download this document for free, or read online. Document in PDF available to download.

Abstract: The so-called -polar catastrophe-, a sudden electronic reconstruction takingplace to compensate for the interfacial ionic polar discontinuity, is currentlyconsidered as a likely factor to explain the surprising conductivity of theinterface between the insulators LaAlO3 and SrTiO3. We applied optical secondharmonic generation, a technique that a priori can detect both mobile andlocalized interfacial electrons, to investigating the electronic polarreconstructions taking place at the interface. As the LaAlO3 film thickness isincreased, we identify two abrupt electronic rearrangements: the first takesplace at a thickness of 3 unit cells, in the insulating state; the secondoccurs at a thickness of 4-6 unit cells, i.e., just above the threshold forwhich the samples become conducting. Two possible physical scenarios behindthese observations are proposed. The first is based on an electronic transferinto localized electronic states at the interface that acts as a precursor ofthe conductivity onset. In the second scenario, the signal variations areattributed to the strong ionic relaxations taking place in the LaAlO3 layer.



Author: A. Savoia, D. Paparo, P. Perna, Z. Ristic, M. Salluzzo, F. Miletto Granozio, U. Scotti di Uccio, C. Richter, S. Thiel, J. Mannhar

Source: https://arxiv.org/







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