Strain-induced single-domain growth of epitaxial SrRuO3 layers on SrTiO3: a high-temperature x-ray diffraction study

Temperature dependent structural phase transitions of SrRuO3 thin films epitaxially grown on SrTiO3(001) single crystal substrates have been studied using high-resolution x-ray diffraction. In contrast to bulk SrRuO3, coherently strained epitaxial layers do not display cubic symmetry up to ~730 oC and remain tetragonal. Such behavior is believed to be induced by compressive strain between the SrRuO3 layer and SrTiO3 substrate due to lattice mismatch. The tetragonal symmetry during growth explains the single domain growth on miscut SrTiO3 substrates with step edges running along the [100] or [010] direction.Comment: 5 pages, 3 figure

Complex plume stoichiometry during pulsed laser deposition of SrVO₃ at low oxygen pressures

To control the pulsed laser deposition synthesis, knowledge on the relationship between the plasma plume and the grown thin film is required. We show that the oxidation of species in the plasma plume still affects the SrVO3 growth even at low oxygen partial pressures. Optical emission spectroscopy measurements for the plasma plume at different growth conditions were correlated with the film properties determined by Atomic force microscopy, X-ray diffraction, and transport. At reducing oxygen pressures, the background argon pressure can affect the oxidation in the plasma plume, which in turn controls the growth kinetics, stoichiometry, and electrical properties of the films

Quantum Anomalous Hall State in Ferromagnetic SrRuO3_3 (111) Bilayers

SrRuO$_3$ heterostructures grown in the (111) direction are a rare example of thin film ferromagnets. By means of density functional theory plus dynamical mean field theory we show that the half-metallic ferromagnetic state with an ordered magnetic moment of 2$\mu_{B}$/Ru survives the ultimate dimensional confinement down to a bilayer, even at elevated temperatures of 500$\,$K. In the minority channel, the spin-orbit coupling opens a gap at the linear band crossing corresponding to $\frac34$ filling of the $t_{2g}$ shell. We demonstrate that the respective state is Haldane's quantum anomalous Hall state with Chern number $C$=1, without an external magnetic field or magnetic impurities.Comment: 5 pages, 3 figure

Stabilization of the perovskite phase in the Y-Bi-O system by using a BaBiO3_{3} buffer layer

A topological insulating phase has theoretically been predicted for the thermodynamically unstable perovskite phase of YBiO$_{3}$. Here, it is shown that the crystal structure of the Y-Bi-O system can be controlled by using a BaBiO$_{3}$ buffer layer. The BaBiO$_{3}$ film overcomes the large lattice mismatch of 12% with the SrTiO$_{3}$ substrate by forming a rocksalt structure in between the two perovskite structures. Depositing an YBiO$_{3}$ film directly on a SrTiO$_{3}$ substrate gives a fluorite structure. However, when the Y-Bi-O system is deposited on top of the buffer layer with the correct crystal phase and comparable lattice constant, a single oriented perovskite structure with the expected lattice constants is observed.Comment: 8 pages, 7 figures + 4 pages supporting informatio

On the importance of the SrTiO₃ template and the electronic contact layer for the integration of phase-pure low hysteretic Pb(Mg_0.33Nb_0.67)O₃-PbTiO₃ layers with Si

The rapid advent of the piezoelectric microelectromechanical systems (PiezoMEMS) field has created a tremendous demand for low hysteretic piezoelectric thin films on Si. In this work, we present the integration of epitaxial Pb(Mg0.33Nb0.67)O3-PbTiO3 (PMN-PT) thin films with Si to enable device fabrication using state of the art methods. With optimized buffer layers and electronic contacts, high-quality low hysteretic PMN-PT thin films are integrated with Si, which is a significant stride towards employing PMN-PT thin film for PiezoMEMS devices. It is found that the processing of the necessary SrTiO3 buffer layer is crucial to achieve the growth of phase-pure perovskite PMN-PT layers on Si. Furthermore, we propose the engineering of the electronic contact for the PMN-PT-on-Si capacitors to obtain low hysteretic polarization and displacement responses.</p

Determining the energetics of vicinal perovskite oxide surfaces

The energetics of vicinal SrTiO$_3$(001) and DyScO$_3$(110), prototypical perovskite vicinal surfaces, has been studied using topographic atomic force microscopy imaging. The kink formation and strain relaxation energies are extracted from a statistical analysis of the step meandering. Both perovskite surfaces have very similar kink formation energies and exhibit a similar triangular step undulation. Our experiments suggest that the energetics of perovskite oxide surfaces is mainly governed by the local oxygen coordination.Comment: 16 pages, 4 figure