Variable-temperature infrared microscopy of conducting oxide interfaces

Probing the local transport properties of two-dimensional electron systems confined at buried interfaces requires a non-invasive technique with a high spatial resolution. Using a scattering-type scanning near field optical microscopy, we study the conducting LaAlO₃/SrTiO₃ interface from room temperature down to 6 K [1]. We observe that the near-field optical signal is highly sensitive to the transport properties of the electron system. According to our model, such sensitivity originates from the interaction of the AFM tip with coupled plasmon–phonon modes.
[1] W. Luo et al., Nat. Commun. 10, 2774 (2019)