Structural coupling across the LaAlO_{3}/SrTiO_{3} interface: High-resolution x-ray diffraction study (original) (raw)
Structural Basis for the Conducting Interface between LaAlO_ {3} and SrTiO_ {3}
2007
The complete atomic structure of a five-monolayer film of LaAlO3 on SrTiO3 has been determined for the first time by surface x-ray diffraction in conjunction with the coherent Bragg rod analysis phaseretrieval method and further structural refinement. Cationic mixing at the interface results in dilatory distortions and the formation of metallic La1ÿxSrxTiO3.
Structural Comparison of n-Type and p-Type LaAlO_{3}/SrTiO_{3} Interfaces
Physical Review Letters, 2011
Using a surface x-ray diffraction technique, we investigated the atomic structure of two types of interfaces between LaAlO 3 and SrTiO 3 , that is, p-type (SrO/AlO 2) and n-type (TiO 2 /LaO) interfaces. Our results demonstrate that the SrTiO 3 in the sample with the n-type interface has a large polarized region, while that with the p-type interface has a limited polarized region. In addition, the atomic intermixing was observed to extend deeper into STO substrate at the n-type interface than at the p-type. These differences result in different degrees of band bending, which likely contributes to the striking difference in electrical conductivity between the two types of interfaces.
Electronic properties of LaAlO3/SrTiO3n-type interfaces: a GGA+Ustudy
Journal of Physics: Condensed Matter, 2017
The rôle of electronic correlation effects for a realistic description of the electronic properties of LaAlO 3 /SrTiO 3 heterostructures as covered by the onsite Coulomb repulsion within the GGA+U approach is investigated. Performing a systematic variation of the values of the Coulomb parameters applied to the Ti 3d and La 4f orbitals we put previous suggestions to include a large value for the La 4f states into perspective. Furthermore, our calculations provide deeper insight into the band gap landscape in the space spanned by these Coulomb parameters and the resulting complex interference effects. In addition, we identify important correlations between the local Coulomb interaction within the La 4f shell, the band gap, and the atomic displacements at the interface. In particular, these on-site Coulomb interactions influence buckling within the LaO interface layer, which via its strong coupling to the electrostatic potential in the LAO overlayer causes considerable shifts of the electronic states at the surface and eventually controls the band gap.
Journal of Applied Physics, 2018
Hetero-interfaces between epitaxial LaAlO3 films and SrTiO3 substrates can exhibit an insulator-metal transition at a critical film thickness above which a quasi-two-dimensional electron gas forms. This work aims to elucidate the significant role defects play in determining the sources of non-mobile and mobile carriers, the critical thickness, and the dipolar field screening. A model is built based on a comprehensive investigation of the origin of the charge carriers and advanced analysis of structural factors that affect the electronic properties of these hetero-epitaxial interfaces.
Structure-Property Relation of SrTiO3-LaAlO3 Interfaces
2008
A large variety of transport properties have been observed at the interface between the insulating oxides SrTiO 3 and LaAlO 3 such as insulation, 2D interface metallicity, 3D bulk metallicity, magnetic scattering, and superconductivity. The relation between the structure and the properties of the SrTiO 3 /LaAlO 3 interface can be explained in a meaningful way by taking into account the relative contribution of three structural aspects: oxygen vacancies, structural deformations (including cation disorder), and electronic interface reconstruction. The emerging phase diagram is much richer than for related bulk oxides due to the occurrence of interface electronic reconstruction. The observation of this interface phenomenon is a display of recent advances in thin film deposition and characterization techniques, and provides an extension to the range of exceptional electronic properties of complex oxides.
Polarization-controlled synchrotron radiation was used to map the electronic structure of buried conducting interfaces of LaAlO 3 /SrTiO 3 in a resonant angle-resolved photoemission experiment. A strong polarization dependence of the Fermi surface and band dispersions is demonstrated, highlighting different Ti 3d orbitals involved in two-dimensional (2D) conduction. Measurements on samples with different doping levels reveal different band occupancies and Fermi-surface areas. The photoemission results are directly compared with advanced first-principles calculations, carried out for different 3d-band filling levels connected with the 2D mobile carrier concentrations obtained from transport measurements, with indication of charge localization at the interface.
High mobility in LaAlO3/SrTiO3 heterostructures: Origin, dimensionality, and perspectives
Physical Review Letters, 2007
We have investigated the dimensionality and origin of the magnetotransport properties of LaAlO3 films epitaxially grown on TiO2-terminated SrTiO3(001) substrates. High mobility conduction is observed at low deposition oxygen pressures (PO2 < 10 −5 mbar) and has a three-dimensional character. However, at higher PO2 the conduction is dramatically suppressed and nonmetallic behavior appears. Experimental data strongly support an interpretation of these properties based on the creation of oxygen vacancies in the SrTiO3 substrates during the growth of the LaAlO3 layer. When grown on SrTiO3 substrates at low PO2, other oxides generate the same high mobility as LaAlO3 films. This opens interesting prospects for all-oxide electronics. PACS numbers: 73.40.-c, 73.50.Fq, 66.30.Jt
ACS Applied Materials & Interfaces, 2011
Transition metal oxides exhibit a huge variety of intrinsic functionalities such as magnetism, superconductivity, thermoelectricity, ferroelectricity or multiferroic behavior. 1À26 Experimentally, there is also growing interest in the creation of "oxide heterostructures" consisting of alternating layers of different transitionÀmetal oxides. 2,3 OxideÀoxide interfaces often give rise to novel physical phenomena not exhibited in the bulk constituents, due to the rearrangement of charge, spins, orbitals, lattice and the resulting rebalancing of their mutual interactions. Thus interface can be exploited to modify electronic structure and to tailor novel properties and behaviors.