Electronic structure of the SrTiO3/LaAlO3 interface revealed by resonant soft x-ray scattering (original) (raw)
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Structure-Property Relation of SrTiO3-LaAlO3 Interfaces
2008
A large variety of transport properties have been observed at the interface between the insulating oxides SrTiO 3 and LaAlO 3 such as insulation, 2D interface metallicity, 3D bulk metallicity, magnetic scattering, and superconductivity. The relation between the structure and the properties of the SrTiO 3 /LaAlO 3 interface can be explained in a meaningful way by taking into account the relative contribution of three structural aspects: oxygen vacancies, structural deformations (including cation disorder), and electronic interface reconstruction. The emerging phase diagram is much richer than for related bulk oxides due to the occurrence of interface electronic reconstruction. The observation of this interface phenomenon is a display of recent advances in thin film deposition and characterization techniques, and provides an extension to the range of exceptional electronic properties of complex oxides.
Physical Review B, 2011
Here, we demonstrate a structural interaction between LaAlO 3 thin films and SrTiO 3 substrates using highresolution x-ray diffraction. X-ray diffraction profiles reveal the presence of periodic lattice distortions in the LaAlO 3 thin films, whose in-plane periodicity is determined by the miscut angle and miscut direction of the substrate. We show that the structural distortions in LaAlO 3 thin films induce similar distortions in the SrTiO 3 substrate.
Electronic and Magnetic Properties of SrTiO3/LaAlO3 Interfaces from First Principles
Advanced Materials, 2010
A number of intriguing properties emerge upon the formation of the epitaxial interface between the insulating oxides LaAlO 3 and SrTiO 3 . These properties, which include a quasi two-dimensional conducting electron gas, low temperature superconductivity, and magnetism, are not present in the bulk materials, generating a great deal of interest in the fundamental physics of their origins. While it is generally accepted that the novel behavior arises as a result of a combination of electronic and atomic reconstructions and growth-induced defects, the complex interplay between these effects remains unclear. In this report, we review the progress that has been made towards unraveling the complete picture of the SrTiO 3 /LaAlO 3 interface, focusing primarily on present ab initio theoretical work and its relation to the experimental data. In the process, we highlight some key unresolved issues and discuss how they might be addressed by future experimental and theoretical studies.
Polarization-controlled synchrotron radiation was used to map the electronic structure of buried conducting interfaces of LaAlO 3 /SrTiO 3 in a resonant angle-resolved photoemission experiment. A strong polarization dependence of the Fermi surface and band dispersions is demonstrated, highlighting different Ti 3d orbitals involved in two-dimensional (2D) conduction. Measurements on samples with different doping levels reveal different band occupancies and Fermi-surface areas. The photoemission results are directly compared with advanced first-principles calculations, carried out for different 3d-band filling levels connected with the 2D mobile carrier concentrations obtained from transport measurements, with indication of charge localization at the interface.
Strong correlations elucidate the electronic structure and phase diagram of LaAlO3/SrTiO3 interface
Nature Communications, 2015
The interface between the two band insulators SrTiO 3 and LaAlO 3 unexpectedly has the properties of a two dimensional electron gas. It is even superconducting with a transition temperature, T c , that can be tuned using gate bias V g , which controls the number of electrons added or removed from the interface. The gate bias -temperature (V g , T) phase diagram is characterized by a domeshaped region where superconductivity occurs, i.e., T c has a non-monotonic dependence on V g , similar to many unconventional superconductors. In this communication the frequency of the quantum resistance-oscillations versus inverse magnetic field is reported for various V g . This frequency follows the same nonmonotonic behavior as T c ; similar trend is seen in the low field limit of the Hall coefficient. We theoretically show that electronic correlations result in a non-monotonic population of the mobile band, which can account for the experimental behavior of the normal transport properties and the superconducting dome.
Nonlinear Optical Response of SrTiO3/LaAlO3 Superlattices
The electronic symmetry of the SrTiO3/LaAlO3 interface was investigated by optical second harmonic generation, using superlattices with varying periodicity to study the evolution of the electronic reconstruction while avoiding substrate contributions. The superlattices show large perpendicular optical nonlinearity, which abruptly increases when the sublattice thickness goes above 3 unit cells, revealing substantial effects of the polar-nonpolar interface. The nonlinear 'active' area is primarily in SrTiO3, develops with increasing thickness, and extends up to 8 unit cells from the interface.
Structural Basis for the Conducting Interface between LaAlO_ {3} and SrTiO_ {3}
2007
The complete atomic structure of a five-monolayer film of LaAlO3 on SrTiO3 has been determined for the first time by surface x-ray diffraction in conjunction with the coherent Bragg rod analysis phaseretrieval method and further structural refinement. Cationic mixing at the interface results in dilatory distortions and the formation of metallic La1ÿxSrxTiO3.
Physical Review B, 2010
We present a first-principles study of the electronic structures and properties of ideal (atomically sharp) LaAlO 3 / SrTiO 3 (001) heterointerfaces and their variants such as a new class of quantum well systems. We demonstrate the insulating-to-metallic transition as a function of the LaAlO 3 film thickness in these systems. After the phase transition, we find that conduction electrons are bound to the n-type interface while holes diffuse away from the p-type interface, and we explain this asymmetry in terms of a large hopping matrix element that is unique to the n-type interface.