Ferromagnetic Quasi-Two-Dimensional Electron Gas with Trigonal Crystal Field Splitting Ferromagnetic Quasi-Two-Dimensional Electron Gas with Trigonal Crystal Field Splitting AITranslate

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DOI：https://doi.org/10.1021/acsaelm.2c00447

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Interfacial inversion symmetry breaking gives rise to electronic properties that differ substantially from those of the bulk constituent materials. Here, we report on the realization of an artificial ferromagnetic quasi-two-dimensional electron gas (q2DEG) at the (111) interfaces between LaAlO3, EuTiO3, and SrTiO3 characterized by a reconstruction of the bulk quasioctahedral crystal field into a trigonal one. The q2DEG is created through a transfer of electrons to the EuTiO3 layers at the interface with LaAlO3, extending into the first layers of SrTiO3, as shown by an electron-energy-loss spectroscopy map of the titanium valence with atomic column resolution. Interestingly, polarized X-ray absorption spectroscopy shows that the Eu-4f and the Ti-3d magnetic moments order ferromagnetically and exhibit the same magnetic field dependence at low temperature. In addition, the q2DEG presents a sizable in-plane orbital moment even at low magnetic field (0.1 T) possibly related to Ti-3d electrons occupying bands with the main a1g orbital character. The results show an intriguing interplay between ferromagnetism, spin–orbit coupling, and trigonal crystal field splitting in the (111) LaAlO3/EuTiO3/SrTiO3 q2DEG.