Low temperature near-field fingerprint spectroscopy of 2D electron systems in oxide heterostructures and beyond

Julian Barnett; Konstantin G. Wirth; Richard Hentrich; Yasin C. Durmaz; Marc-André Rose; Felix Gunkel; Thomas Taubner

doi:10.1038/s41467-025-59633-1

journal article Open Access May 13, 2025

Low temperature near-field fingerprint spectroscopy of 2D electron systems in oxide heterostructures and beyond

Julian Barnett

Konstantin G. Wirth Richard Hentrich Yasin C. Durmaz Marc-André Rose Felix Gunkel

Thomas Taubner

Nature Communications Vol. 16 No. 1 · Springer Science and Business Media LLC

View at Publisher Save 10.1038/s41467-025-59633-1

Abstract

Abstract
Confined electron systems, such as 2D electron gases (2DEGs), 2D materials, or topological insulators, show great technological promise but their susceptibility to defects often results in nanoscale inhomogeneities with unclear origins. Scattering-type scanning near-field optical microscopy (s-SNOM) is useful to investigate buried confined electron systems non-destructively with nanoscale resolution, however, a clear separation of carrier concentration and mobility was so far impossible in s-SNOM. Here, we predict a previously inaccessible characteristic “fingerprint” response of the prototypical LaAlO3/SrTiO3 2DEG, and verify it using a state-of-the-art tunable narrow-band laser in mid-infrared cryo-s-SNOM at 8 K. Our modeling allows us to separate the influence of carrier concentration and mobility on fingerprint spectra and to characterize 2DEG inhomogeneities on the nanoscale. Finally, we model the surface accumulation layer in doped InAs, to show that our fingerprint spectra are a universal feature and generally applicable to confined electron systems, like topological insulators or stacked van-der-Waals materials.

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Published: May 13, 2025
Vol/Issue: 16(1)
License: View

Authors

Leibniz-Institute for Solid State and Materials Research, 01069 Dresden, Germany

Peter Gruenberg Institute 7, Forschungszentrum Juelich GmbH, 52425 Juelich, Germany; JARA-FIT, RWTH Aachen University, 52056 Aachen, Germany

T

Thomas Taubner

I. Institute of Physics (IA) RWTH Aachen University D‐52056 Aachen Germany

Funding

Deutsche Forschungsgemeinschaft Award: SFB 917

Cite This Article

Julian Barnett, Konstantin G. Wirth, Richard Hentrich, et al. (2025). Low temperature near-field fingerprint spectroscopy of 2D electron systems in oxide heterostructures and beyond. Nature Communications, 16(1). https://doi.org/10.1038/s41467-025-59633-1

Low temperature near-field fingerprint spectroscopy of 2D electron systems in oxide heterostructures and beyond

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