Atomic-scale observation of a graded polar discontinuity and a localized two-dimensional electron density at an insulating oxide interface

C. P. Chang, J. G. Lin, H. T. Jeng, S. L. Cheng, W. F. Pong, Y. C. Shao, Y. Y. Chin, H. J. Lin, C. W. Chen, J. R. Yang, C. H. Chen, M. W. Chu

Research output: Contribution to journalArticlepeer-review

16 Scopus citations

Abstract

Using atomically resolved electron energy-loss spectroscopy, the atomic-plane-by-atomic-plane, unit-cell-by-unit-cell stoichiometry, and charge characteristics of the oxide interface (Nd0.35Sr0.65) MnO3/SrTiO3, with a primitive polar discontinuity of (Nd0.35Sr0.65O)0.35+-(TiO2)0, were thoroughly investigated. (Nd0.35Sr0.65)MnO3 is a strongly correlated insulator and the interface was characterized to be insulating. The cell-specific stoichiometric evaluation unveiled an extensive interdiffusion across the interface. The plane-specific charge characterization revealed that the interdiffusion grades the primitive polar discontinuity. Despite the graded polar discontinuity, a charge transfer inversely into (Nd0.35Sr0.65)MnO3 was firmly resolved with a length scale of ∼2 nm and a charge density on the order of ∼1013/cm2 and is effectively mediated by an asymmetric Ti interdiffusion. The intricate electronic correlations of the interfacial (Nd0.35Sr 0.65)MnO3 unit cells and the interdiffusion-induced chemical disorder tend to render the charges localized, resulting in a localized two-dimensional electron density and thus the insulating interface, in distinct contrast to the conventional understanding of a vanishing charge density for an insulating interface and the metallic two-dimensional electron gas found at other classical polar-discontinuous interface systems. A potential strain manipulation on the electronic localization of the electron density was also proposed.

Original languageEnglish
Article number075129
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume87
Issue number7
DOIs
StatePublished - 19 Feb 2013

Fingerprint

Dive into the research topics of 'Atomic-scale observation of a graded polar discontinuity and a localized two-dimensional electron density at an insulating oxide interface'. Together they form a unique fingerprint.

Cite this