Anomalous orbital structure in a spinel-perovskite interface $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$

Abstract

In all archetypical reported (001)-oriented perovskite heterostructures, it has been deduced that the preferential occupation of two-dimensional electron gases is in-plane $d_{\text{xy}}$ state. In sharp contrast to this, the investigated electronic structure of a spinel-perovskite heterostructure $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$ by resonant soft X-ray linear dichroism, demonstrates that the preferential occupation is out-of-plane $d_{\text{xz}}$/$d_{\text{yz}}$ states for interfacial electrons. Moreover, the impact of strain further corroborates that this anomalous orbital structure can be linked to the altered crystal field at the interface and symmetry breaking of the interfacial structural units. Our findings provide another interesting route to engineer emergent quantum states with deterministic orbital symmetry.

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References in corpus (6)

• Superconductivity in single-layer films of FeSe with a transition temperature above 100 K
• Theory of spin-orbit coupling at LaAlO3/SrTiO3 interfaces and SrTiO3 surfaces
• A high-mobility two-dimensional electron gas at the heteroepitaxial spinel/perovskite complex oxide interface of γ-Al2O3/SrTiO3
• Emergent properties hidden in plane view: Strong electronic correlations at oxide interfaces
• Control of a two-dimensional electron gas on SrTiO3(111) by atomic oxygen
• Large modulation of the Shubnikov-de Haas oscillations by the Rashba interaction at the LaAlO${}_3$/SrTiO${}_3$ interface

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• Band-Order Anomaly at the γ-Al2O3/SrTiO3 Interface Drives the Electron-Mobility Boost
• Suppressed carrier density for the patterned high mobility two-dimensional electron gas at gamma-Al2O3/SrTiO3 heterointerfaces
• Electron trapping and detrapping in an oxide two-dimensional electron gas: The role of ferroelastic twin walls
• Ferroelectric control of spin-polarized two-dimensional electron gas
• Engineered Kondo screening and nonzero Berry phase in SrTiO3/LaTiO3/SrTiO3 heterostructures
• Coexistence of high electron-mobility, unpaired spins, and superconductivity at high carrier density SrTiO${}_3$-based interfaces
• High-mobility two-dimensional electron gas in $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$ heterostructures
• Beyond being free: glassy dynamics of SrTiO${}_3$-based two-dimensional electron gas
• Orthorhombic distortion drives orbital ordering in an antiferromagnetic 3$d^1$ Mott insulator
• Leveraging high fluence and low pressure for pulsed laser deposition of high-mobility $\gamma$-Al${}_2$O${}_3$/SrTiO${}_3$ heterostructure growth