Interface engineering of quantum Hall effects in digital transition metal oxide heterostructures

Topological insulators are characterized by a nontrivial band topology driven by the spin-orbit coupling. To fully explore the fundamental science and application of topological insulators, material realization is indispensable. Here we predict, based on tight-binding modeling and first-principles calculations, that bilayers of perovskite-type transition-metal oxides grown along the [111] crystallographic axis are potential candidates for two-dimensional topological insulators. The topological band structure of these materials can be fine-tuned by changing dopant ions, substrates, and external gate voltages. We predict that LaAuO$_3$ bilayers have a topologically-nontrivial energy gap of about 0.15 eV, which is sufficiently large to realize the quantum spin-Hall effect at room temperature. Intriguing phenomena, such as fractional quantum Hall effect, associated with the nearly-flat topologically-nontrivial bands found in $e_g$ systems are also discussed.Comment: Main text 11 pages with 4 figures and 1 table. Supplementary materials 4 pages with 2 figure

Comparison of the Electron Momentum and 2-Photon Momentum Distributions in Titanium and Zirconium Dihydrides

Journal URL: http://www.z-phys-chem.d

Interaction of dioxygen with Al clusters and Al(111): A comparative theoretical study

We have studied the interaction of an oxygen molecule with Al clusters and Al(111) using both wave-function-based quantum chemistry methods and density functional theory (DFT). These calculations were motivated by the fact that molecular beam experiments indicate that the adsorption of O2 on Al(111) should be activated whereas periodic DFT calculations yield purely attractive adsorption paths for almost all impact configurations of O 2 on Al(111). On small Al4 clusters, accurate wave-function-based quantum chemistry methods find a non-vanishing barrier in the O2 adsorption. The DFT calculations for slabs and larger Al clusters confirm the important role of spin effects for the O2 dissociation barrier on Al. The results indicate that exchange-correlation effects play a crucial role for the determination of the adsorption barrier in the O2/Al system but their determination is hampered by serious technical problems that are discussed in detail. © 2008 American Chemical Society

Calculation of the Electron Momentum Density and Compton-Scattering Measurements for Nickel

Journal URL: http://www.iop.org/EJ/journal/JPhysC