High sensitivity variable-temperature infrared nanoscopy of conducting oxide interfaces

Abstract

Probing the local transport properties of two-dimensional electron systems (2DES) confined at buried interfaces requires a non-invasive technique with a high spatial resolution operating in a broad temperature range. In this paper, we investigate the scattering-type scanning near field optical microscopy as a tool for studying the conducting LaAlO3/SrTiO3 interface from room temperature down to 6 K. We show that the near-field optical signal, in particular its phase component, is highly sensitive to the transport properties of the electron system present at the interface. Our modelling reveals that such sensitivity originates from the interaction of the AFM tip with coupled plasmon-phonon modes with a small penetration depth. The model allows us to quantitatively correlate changes in the optical signal with the variation of the 2DES transport properties induced by cooling and by electrostatic gating. To probe the spatial resolution of the technique, we image conducting nano-channels written in insulating heterostructures with a voltage-biased tip of an atomic force microscope.

arXiv comment19 pages, 5 figures

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Cited by in corpus (8)

• Thermal and electrostatic tuning of surface phonon-polaritons in LaAlO3/SrTiO3 heterostructures
• A two-dimensional electron gas based on a 5s oxide with high room-temperature mobility and strain sensitivity
• High-index and low-loss topological insulators for mid-infrared nanophotonics
• Electronic transport in sub-micrometric channels at the LaAlO${}_3$/SrTiO${}_3$ interface
• Strongly confined Mid-infrared to Terahertz Phonon Polaritons in Ultra-thin SrTiO3
• Quantitative Analytical Model for Scattering-type Scanning Near-field Optical Spectroscopy
• Quantum Heat Under the Microscope: A Perspective on Cryogenic Scanning Thermal Microscopy
• Superconductivity in Shear Strained Semiconductors