ArXiv · 2026
Dilek Yildiz (Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, USA, Joint Quantum Institute, Department of Physics, University of Maryland, College Park, USA, Department of Advanced Material Science, The University of Tokyo, Chiba, Japan), Sungmin Kim (Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, USA, Joint Quantum Institute, Department of Physics, University of Maryland, College Park, USA), Dengyu Yang (Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, USA, Joint Quantum Institute, Department of Physics, University of Maryland, College Park, USA, Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, USA), Muqing Yu (Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, USA), Kyoungjun Lee (Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, USA), Ruiqi Sun (Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, USA), En-Min Shih (Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, USA, Department of Chemistry and Biochemistry, University of Maryland, College Park, USA), Steven R. Blankenship (Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, USA), Patrick Irvin (Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, USA), Franz J. Giessibl (Institute of Experimental and Applied Physics, University of Regensburg, Regensburg, Germany), Chang-Beom Eom (Department of Materials Science and Engineering, University of Wisconsin-Madison, Madison, USA), Jeremy Levy (Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, USA), Joseph A. Stroscio (Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, USA)
Superconductivity in strontium titanate has remained enigmatic for more than 50 years. The LaAlO₃/SrTiO₃ (LAO/STO) heterointerface enables systematic dimensional confinement, from a two-dimensional electron gas to quasi-one-dimensional nanostructures, providing access to this quantum state. Transport measurements in patterned devices reveal puzzling phenomena, including width-independent critical currents and anomalous pairing suggestive of one-dimensional behavior, but direct local probes of the patterned interface and its superconducting response have been lacking. Here we use ultralow-temperature non-contact atomic force microscopy, dissipation spectroscopy, and Kelvin probe force microscopy to locally probe signatures of superconductivity in patterned LAO/STO devices. Spatially resolved energy-dissipation measurements reveal superconducting signatures, with features confined in some devices to edge channels approximately 200 nm wide. Dissipation spectra exhibit a characteristic nonlinear bias dependence that provides a local diagnostic of superconductivity, consistent with the intermediate carrier-density regime near the superconducting dome, and persisting up to the critical field. These results establish atomic force microscopy as a local probe of superconductivity in patterned LAO/STO structures and provide a route to addressing longstanding questions about quantum confinement and transport anomalies in correlated oxide nanostructures.
