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TT: Fachverband Tiefe Temperaturen

TT 58: SrTiO₃: A Versatile Material from Bulk Quantum Paraelectric to 2D Superconductor: Poster (joint session TT/KFM/MA/O)

TT 58.4: Poster

Wednesday, March 20, 2024, 15:00–18:00, Poster E

ferromagnetic two-dimensional electron gas in oxide interfaces — •Yu Chen¹, Maria D’Antuono^1,2, Martando Rath¹, Cinthia Piamonteze³, Daniele Preziosi⁴, Benoit Jouault⁵, Daniela Stornaiuolo^1,2, and Marco Salluzzo¹ — ¹CNR-SPIN, Napoli, Italy — ²Università di Napoli ”Federico II”, Italy — ³Photon Science Division, Paul Scherrer Institut, Switzerland — ⁴Université de Strasbourg, CNRS, IPCMS UMR, France — ⁵Laboratoire Charles Coulomb, UMR 5221, CNRS, Université de Montpellier, France

Interfacial inversion symmetry breaking triggers novel phenomena not observed in bulk materials, such as unconventional superconductivity and magnetism. Here, we report on the realization of ferromagnetic two-dimensional electron gas (2DEG) at (001) and (111) interfaces between LaAlO₃, EuTiO₃, and SrTiO₃. At variance with the octahedral and quasi-octahedral symmetry in bulk SrTiO₃ and (001) interface, trigonal crystal field is reconstructed at (111) interface. The experiments of transport, magnetic and x-ray spectroscopy indicate that the filling of Ti 3d bands in the EuTiO₃ layer and at the interface with SrTiO₃ induces an exchange interaction between Eu-4f⁷ magnetic moments. We observe carrier density-dependent ferromagnetic correlations and anomalous Hall effect, sizable in-plane orbital moment possibly related to Ti-3d electrons occupying bands with the main 3d_xz,zy and a_1g orbital characters at (001) and (111) interfaces, respectively. Our findings show intriguing interplay between ferromagnetism, spin-orbit coupling, and symmetry breaking at oxide 2DEG, serving as a guide for the materials design of advanced spintronics.

Keywords: spin-polarized 2DEG; trigonal crystal field; multi-orbital; x-ray spectroscopy; oxide interfaces