Anisotropic transport at the LaAlO3/SrTiO3 interface explained by microscopic imaging of channel-flow over SrTiO3 domains

Abstract

Oxide interfaces, including the LaAlO3/SrTiO3 interface, have been a subject of intense interest for over a decade due to their rich physics and potential as low dimensional nanoelectronic systems. The field has reached the stage where efforts are invested in developing devices. It is critical now to understand the functionalities and limitations of such devices. Recent scanning probe measurements of the LaAlO3/SrTiO3 interface have revealed locally enhanced current flow and accumulation of charge along channels related to SrTiO3 structural domains. These observations raised a key question regarding the role these modulations play in the macroscopic properties of devices. Here we show that the microscopic picture, mapped by scanning superconducting quantum interference device, accounts for a substantial part of the macroscopically measured transport anisotropy. We compared local flux data with transport values, measured simultaneously, over various SrTiO3 domain configurations. We show a clear relation between maps of local current density over specific domain configurations and the measured anisotropy for the same device. The domains divert the direction of current flow, resulting in a direction dependent resistance. We also show that the modulation can be significant and that in some cases up to 95% of the current is modulated over the channels. The orientation and distribution of the SrTiO3 structural domains change between different cooldowns of the same device or when electric fields are applied, affecting the device behavior. Our results, highlight the importance of substrate physics, and in particular, the role of structural domains, in controlling electronic properties of LaAlO3/SrTiO3 devices. Further, these results point to new research directions, exploiting the STO domains ability to divert or even carry current.

arXiv commentin ACS Appl. Mater. Interfaces, Article ASAP, 2016

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• Imaging and tuning polarity at SrTiO3 domain walls
• Six-fold crystalline anisotropic magnetoresistance in the (111) LaAlO${}_3$/SrTiO${}_3$ oxide interface
• One-Dimensional Nature of Pairing and Superconductivity at the LaAlO${}_3$/SrTiO${}_3$ Interface
• Direct reconstruction of two-dimensional currents in thin films from magnetic field measurements
• Coupling lattice instabilities across the interface in ultrathin oxide heterostructures
• Anisotropic electrical resistance in mesoscopic LaAlO${}_3$/SrTiO${}_3$ devices with individual domain walls
• Anisotropic, multi-carrier transport at the (111) LaAlO${}_3$/SrTiO${}_3$ interface
• Non-universal current flow near the metal-insulator transition in an oxide interface
• Bimodal Phase Diagram of the Superfluid Density in LaAlO3/SrTiO3 Revealed by an Interfacial Waveguide Resonator
• Large-scale modulation in the superconducting properties of thin films due to domains in the $SrTi{O}_3$ substrate
• Signatures of Electronic Nematicity in (111) LaAlO${}_3$/SrTiO${}_3$ Interfaces
• Electron Pairing and Nematicity in LaAlO${}_3$/SrTiO${}_3$ Nanostructures
• Observation of zero-field transverse resistance in AlO${}_x$/SrTiO${}_3$ interface devices
• Influence of the vicinal substrate miscut on the anisotropic two-dimensional electronic transport in Al2O3-SrTiO3 heterostructures
• Anisotropic magnetotransport in LaAlO${}_3$/SrTiO${}_3$ nanostructures
• Temperature dependent giant resistance anomaly in LaAlO3/SrTiO3 nanostructures