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O: Fachverband Oberflächenphysik

O 101: Focus Session: SrTiO₃: A Versatile Material from Bulk Quantum Paraelectric to 2D Superconductor III (joint session TT/KFM/MA/O)

O 101.1: Talk

Friday, March 22, 2024, 09:30–09:45, H 0104

High-mobility two-dimensional electron gases based on strain engineered ferroelectric SrTiO₃ thin films — •Ruchi Tomar¹, Tatiana Kuznetsova², Srijani Mallik¹, Luis M. Vicente-Arche¹, Fernando Gallego¹, Maximilien Cazayous³, Roman Engel-Herbert^2,4, and Manuel Bibes¹ — ¹Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767 Palaiseau, France. — ²Pennsyvlania State University, University Park, PA 16802, USA. — ³Laboratoire Matériaux et Phénomènes Quantiques (UMR 7162 CNRS), Université de Paris, 75205 Paris Cedex 13, France. — ⁴Paul Drude Institute for Solid State Electronics, Leibniz Institute within Forschungsverbund Berlin eV, Hausvogteiplatz 5-7, 10117, Berlin, Germany.

Two-dimensional electron gases (2DEGs) based on the quantum paraelectric SrTiO₃ display fascinating properties such as large electron mobilities, superconductivity, and efficient spin-charge interconversion owing to their Rashba spin-orbit coupling. Here, we use oxide molecular beam epitaxy to grow high-quality strain-engineered SrTiO₃ films that are ferroelectric up to 170 K. We then generate a 2DEG by sputtering a thin Al layer and demonstrate an increase in mobilities compared to earlier literature. Furthermore, through Raman spectroscopy and magneto-transport measurements, we show that the ferroelectric character is retained after 2DEG formation. These results thus qualify our samples as ferroelectric 2DEGs up to temperatures well above previous results based on Ca-SrTiO₃ substrates, opening the way towards ferroelectric 2DEGs operating at room temperature.

Keywords: two-dimensional electron gas; Epitaxial strain; Ferroelectricity; Raman spectroscopy