Symmetry breaking at the (111) interfaces of SrTiO${}_3$ hosting a 2D-electron system

Abstract

We used x-ray absorption spectroscopy to study the orbital symmetry and the energy band splitting of (111) LaAlO${}_3$/SrTiO${}_3$ and LaAlO${}_3$/EuTiO${}_3$/SrTiO${}_3$ heterostructures, hosting a quasi two-dimensional electron system (q2DES), and of a Ti-terminated (111) SrTiO${}_3$ single crystal, also known to form a q2DES at its surface. We demonstrate that the bulk tetragonal Ti-3d D${}_4$${}_h$ crystal field is turned into trigonal D${}_3$${}_d$ crystal field in all cases. The symmetry adapted a${}_1$${}_g$ and e${}_g^{\pi }$ orbitals are non-degenerate in energy and their splitting, Δ, is positive at the bare STO surface but negative in the heterostructures, where the a${}_1$${}_g$ orbital is lowest in energy. These results demonstrate that the interfacial symmetry breaking induced by epitaxial engineering of oxide interfaces has a dramatic effect on their electronic properties, and it can be used to manipulate the ground state of the q2DES.

arXiv comment6 pages article, plus 5 pages supplementary information

References in corpus (16)

• Tunable Rashba spin-orbit interaction at oxide interfaces
• Unveiling a two-dimensional electron gas with universal subbands at the surface of SrTiO3
• Creation and control of a two-dimensional electron liquid at the bare SrTiO3 surface
• Interface engineering of quantum Hall effects in digital transition metal oxide heterostructures
• Orbital reconstruction and two-dimensional electron gas at the LaAlO3/SrTiO3 interface
• High mobility conduction at (110) and (111) LaAlO3/SrTiO3 interfaces
• Direct k-space mapping of the electronic structure in an oxide-oxide interface
• Conducting interfaces between band insulating oxides: the LaGaO3/SrTiO3
• Anisotropic two-dimensional electron gas at SrTiO3(110) protected by its native overlayer
• Control of a two-dimensional electron gas on SrTiO3(111) by atomic oxygen
• Observation of out-of-plane spin texture in a SrTiO3 (111) two-dimensional electron gas
• Massive symmetry breaking in LaAlO${}_3$/SrTiO${}_3$(111) quantum wells: a three-orbital, strongly correlated generalization of graphene
• Doping-dependent band structure of LaAlO${}_3$/SrTiO${}_3$ interfaces by soft x-ray polarization-controlled resonant angle-resolved photoemission
• Two-dimensional superconductivity at the (111)LaAlO${}_3$/SrTiO${}_3$ interface
• Orientational tuning of the Fermi sea of confined electrons at the SrTiO3 (110) and (111) surfaces
• Link between the Superconducting Dome and Spin-Orbit Interaction in the (111) LaAlO${}_3$/SrTiO${}_3$ Interface

Cited by in corpus (10)

• Designing spin and orbital sources of Berry curvature at oxide interfaces
• Band Structure and Spin-Orbital Texture of the (111)-KTaO3 Two-Dimensional Electron Gas
• Band inversion driven by electronic correlations at the (111) LaAlO${}_3$/SrTiO${}_3$ interface
• Symmetry and correlation effects on band structure explain the anomalous transport properties of (111) LaAlO${}_3$/SrTiO${}_3$
• Orbital design of Berry curvature: pinch points and giant dipoles induced by crystal fields
• Tunable spin and orbital Edelstein effect at (111) LaAlO${}_3$/SrTiO${}_3$ interface
• Gate tunable anomalous Hall effect: a Berry curvature probe at oxides interfaces
• Strain-induced topological phase transition at (111) SrTiO${}_3$-based heterostructures
• Effect of confinement and Coulomb interactions on the electronic structure of (111) LaAlO${}_3$/SrTiO${}_3$ interface
• Dirac-like fermions anomalous magneto-transport in a spin-polarized oxide two-dimensional electron system