New insights into the electron trapping mechanism in LaAlO_3 / SrTiO3 heterostructures

Abstract

In LaAlO3/SrTiO3 heterostructures, a commonly observed but poorly understood phenomenon is that of electron trapping in back-gating experiments. In this work, by combining magnetotransport measurements and self-consistent Schroedinger-Poisson calculations, we obtain an empirical relation between the amount of trapped electrons and the gate voltage. We find that the trapped electrons follow an exponentially decaying spatial distribution away from the interface. However, contrary to earlier observations, we find that the Fermi level remains well within the quantum well. The enhanced trapping of electrons induced by the gate voltage can therefore not be explained by a thermal escape mechanism. Further gate sweeping experiments strengthen our conclusion that the thermal escape mechanism is not valid. We propose a new mechanism which involves the electromigration and clustering of oxygen vacancies in SrTiO3. Our work indicates that electron trapping is a universal phenomenon in SrTiO3-based two-dimensional electron systems.

manuscript + supplementary information, 8 pages

References in corpus (28)

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• Magnetic effects at the interface between nonmagnetic oxides
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• Tunable Rashba spin-orbit interaction at oxide interfaces
• Direct imaging of the coexistence of ferromagnetism and superconductivity at the LaAlO3/SrTiO3 interface
• Coexistence of Magnetic Order and Two-dimensional Superconductivity at LaAlO${}_3$/SrTiO${}_3$ Interfaces
• Unveiling a two-dimensional electron gas with universal subbands at the surface of SrTiO3
• Mapping the Spatial Distribution of Charge Carriers in LaAlO3/SrTiO3 Heterostructures
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• 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
• Dominant mobility modulation by the electric field effect at the LaAlO_3 / SrTiO_3 interface
• Locally enhanced conductivity due to the tetragonal domain structure in LaAlO${}_3$/SrTiO${}_3$ heterointerfaces
• Visible light enhanced field effect at LaAlO3/SrTiO3 interface
• Imaging and tuning polarity at SrTiO3 domain walls
• Phase separation from electron confinement at oxide interfaces
• Intrinsic instability of electronic interfaces with strong Rashba coupling
• Gate-tunable band structure of the LaAlO${}_3$-SrTiO${}_3$ interface
• Modulation of conductance and superconductivity by top-gating in LaAlO3/SrTiO3 2-dimensional electron systems
• Metal-Insulator Transition of the LaAlO3-SrTiO3 Interface Electron System
• Phase diagrams of voltage-gated oxide interfaces with strong Rashba coupling
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• Anomalous response to gate voltage application in mesoscopic LaAlO_3/SrTiO_3 devices
• Correlation between Superconductivity, Band Filling and Electron Confinement at the LaAlO${}_3$-SrTiO${}_3$ Interface
• Probing Quantum Confinement and Electronic Structure at Polar Oxide Interfaces
• Electrostatic tuning of magnetism at the conducting (111) (La${}_{0.3}$Sr${}_{0.7}$)(Al${}_{0.65}$Ta${}_{0.35}$)/SrTiO${}_3$ interface
• Influence of stoichiometry on interfacial conductance in LaAlO${}_3$/SrTiO${}_3$ grown by 90${}^o$ off-axis sputtering

Cited by in corpus (11)

• Tuning Rashba spin-orbit coupling at LaAlO3/SrTiO3 interfaces by band filling
• Nanoscale control of the metal-insulator transition at LAO/KTO (110) and LAO/KTO (111) interfaces
• Electron trapping and detrapping in an oxide two-dimensional electron gas: The role of ferroelastic twin walls
• Ionic liquid gating of SrTiO${}_3$ lamellas fabricated with a focused ion beam
• Irreversible multi-band effects and Lifshitz transitions at the LaAlO3/SrTiO3 interface under field effect
• Non-collinear and strongly asymmetric polar moments at back-gated SrTiO3 interfaces
• Inhomogeneous superconductivity and quasilinear magnetoresistance at amorphous LaTiO3/SrTiO3 interfaces
• Beyond being free: glassy dynamics of SrTiO${}_3$-based two-dimensional electron gas
• Universally enhanced superconductivity and coexisting ferroelectricity at oxide interfaces
• Two-Dimensional Charge Localization at the Perovskite Oxide Interface
• Density-tuned isotherms and dynamic change at phase transition in a gate-controlled superconducting system