@article{SchenkelUhlemann2010, author = {Schenkel, Alexander and Uhlemann, Christoph F.}, title = {Field Theory on Curved Noncommutative Spacetimes}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68648}, year = {2010}, abstract = {We study classical scalar field theories on noncommutative curved spacetimes. Following the approach of Wess et al. [Classical Quantum Gravity 22 (2005), 3511 and Classical Quantum Gravity 23 (2006), 1883], we describe noncommutative spacetimes by using (Abelian) Drinfel'd twists and the associated ?-products and ?-differential geometry. In particular, we allow for position dependent noncommutativity and do not restrict ourselves to the Moyal-Weyl deformation. We construct action functionals for real scalar fields on noncommutative curved spacetimes, and derive the corresponding deformed wave equations. We provide explicit examples of deformed Klein-Gordon operators for noncommutative Minkowski, de Sitter, Schwarzschild and Randall-Sundrum spacetimes, which solve the noncommutative Einstein equations. We study the construction of deformed Green's functions and provide a diagrammatic approach for their perturbative calculation. The leading noncommutative corrections to the Green's functions for our examples are derived.}, subject = {Physik}, language = {en} } @article{RotheReinthalerLiuetal.2010, author = {Rothe, D. G. and Reinthaler, R. W. and Liu, C-X and Molenkamp, L. W. and Zhang, S-C and Hankiewicz, E. M.}, title = {Fingerprint of different spin-orbit terms for spin transport in HgTe quantum wells}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-68362}, year = {2010}, abstract = {Using k ยท p theory, we derive an effective four-band model describing the physics of the typical two-dimensional topological insulator (HgTe/CdTe quantum well (QW)) in the presence of an out-of-plane (in the z-direction) inversion breaking potential and an in-plane potential. We find that up to third order in perturbation theory, only the inversion breaking potential generates new elements to the four-band Hamiltonian that are off-diagonal in spin space. When this new effective Hamiltonian is folded into an effective twoband model for the conduction (electron) or valence (heavy hole) bands, two competing terms appear: (i) a Rashba spin-orbit interaction originating from inversion breaking potential in the z-direction and (ii) an in-plane Pauli term as a consequence of the in-plane potential. Spin transport in the conduction band is further analysed within the Landauer-B{\"u}ttiker formalism. We find that for asymmetrically doped HgTe QWs, the behaviour of the spin-Hall conductance is dominated by the Rashba term.}, subject = {Physik}, language = {en} } @phdthesis{Margapoti2010, author = {Margapoti, Emanuela}, title = {Optical properties of thermally annealed CdZnSe/ZnSe quantum dots}, url = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-52946}, school = {Universit{\"a}t W{\"u}rzburg}, year = {2010}, abstract = {see: pdf-file}, subject = {Physik}, language = {en} }