Polar catastrophe and electronic reconstructions at the LaAlO3/SrTiO3 interface: evidence from optical second harmonic generation

Abstract

The so-called "polar catastrophe", a sudden electronic reconstruction taking place to compensate for the interfacial ionic polar discontinuity, is currently considered as a likely factor to explain the surprising conductivity of the interface between the insulators LaAlO3 and SrTiO3. We applied optical second harmonic generation, a technique that a priori can detect both mobile and localized interfacial electrons, to investigating the electronic polar reconstructions taking place at the interface. As the LaAlO3 film thickness is increased, we identify two abrupt electronic rearrangements: the first takes place at a thickness of 3 unit cells, in the insulating state; the second occurs at a thickness of 4-6 unit cells, i.e., just above the threshold for which the samples become conducting. Two possible physical scenarios behind these observations are proposed. The first is based on an electronic transfer into localized electronic states at the interface that acts as a precursor of the conductivity onset. In the second scenario, the signal variations are attributed to the strong ionic relaxations taking place in the LaAlO3 layer.

References in corpus (14)

• Magnetic effects at the interface between nonmagnetic oxides
• Why Some Interfaces Cannot be Sharp
• Electric Field Control of the LaAlO${}_3$/SrTiO${}_3$ Interface Ground State
• Origin of charge density at LaAlO3-on-SrTiO3 hetero-interfaces; possibility of intrinsic doping
• Mapping the Spatial Distribution of Charge Carriers in LaAlO3/SrTiO3 Heterostructures
• Avoiding the polarization catastrophe in LaAlO3 overlayers on SrTiO3(001) through a polar distortion
• Orbital reconstruction and two-dimensional electron gas at the LaAlO3/SrTiO3 interface
• Profiling the interface electron gas of LaAlO3/SrTiO3 heterostructures by hard X-ray photoelectron spectroscopy
• Polar Discontinuity Doping of the LaVO_3/SrTiO_3 Interface
• Towards two-dimensional metallic behavior at LaAlO3/SrTiO3 interfaces
• Origin of Metallic States at Heterointerface between Band Insulators LaAlO${}_3$ and SrTiO${}_3$
• Electronic structure induced reconstruction and magnetic ordering at the LaAlO${}_3|$SrTiO${}_3$ interface
• Fundamental asymmetry in interfacial electronic reconstruction between insulating oxides
• Recombination kinetics of a dense electron-hole plasma in strontium titanate

Cited by in corpus (26)

• Physics of SrTiO${}_3$-based heterostructures and nanostructures: a review
• Emergent properties hidden in plane view: Strong electronic correlations at oxide interfaces
• LaAlO3 stoichiometry found key to electron liquid formation at LaAlO3/SrTiO3 interfaces
• Electron transfer and ionic displacements at the origin of the 2D electron gas at the LAO/STO interface: Direct measurements with atomic-column spatial resolution
• Conducting interfaces between band insulating oxides: the LaGaO3/SrTiO3
• Mechanisms of charge transfer and redistribution in LaAlO3/SrTiO3 revealed by high-energy optical conductivity
• Ab Initio Second-Order Nonlinear Optics in Solids: Second-Harmonic Generation Spectroscopy from Time-Dependent Density-Functional Theory
• Localized vs. delocalized character of charge carriers in LaAlO3/ SrTiO3 superlattices
• Pulsed laser deposition of SrTiO3/LaGaO3 and SrTiO3/LaAlO3: plasma plume effects
• Polar catastrophe in ultra-thin limit: A case of rare-earth perovskite LaNiO3
• Blue luminescence of SrTiO3 under intense optical excitation
• Localization of Two-dimensional Electron Gas in LaAlO3/SrTiO3 Heterostructures
• Oxygen Vacancies on SrO-terminated SrTiO3(001) Surfaces studied by Scanning Tunneling Spectroscopy
• Evolution of the SrTiO${}_3$ surface electronic state as a function of LaAlO${}_3$ overlayer thickness
• Reconstruction-Stabilized Epitaxy of LaCoO3/SrTiO3(111) Heterostructures by Pulsed Laser Deposition
• Manipulating the Polar mismatch at LaNiO3/SrTiO3 (111) Interface
• Oxygen-vacancy clustering and pseudogap behaviour at LaAlO3/SrTiO3 interface
• Phase segregation of superconductivity and ferromagnetism at LaAlO${}_3$/SrTiO${}_3$ interface
• Electronic multipoles in second harmonic generation and neutron scattering
• Ultrafast Modification of the Polarity at LaAlO${}_3$/SrTiO${}_3$ Interfaces
• Reversible and Persistent Photoconductivity at the NdGaO3/SrTiO3 Conducting Interface
• Polarity-field driven conductivity in SrTiO${}_3$/LaAlO${}_3$: a hybrid functional study
• Electrostatic treatment of charged interfaces in classical atomistic simulations
• Large electropositive cations as surfactants for the growth of polar epitaxial films
• Charge Fractionalization in Oxide Heterostructures: A Field Theoretical Model
• Temperature dependent giant resistance anomaly in LaAlO3/SrTiO3 nanostructures