arXiv subjects

Udo Schwingenschlögl

Publications and source records attributed to Udo Schwingenschlögl.

22 records · Page 2Linked to original sources

arXiv2012

Modified Li chains as atomic switches

We present electronic structure and transport calculations for hydrogen and lithium chains, using density functional theory and scattering theory on the Green's function level, to systematically study impurity effects on the transmission coefficient. To this end we address various impurity configurations. Tight-binding results allow us to interpret our the findings. We analyze under which circumstances impurities lead to level splitting and/or can be used to switch between metallic and insulating states. We also address the effects of strongly electronegative impurities.

cond-mat.mes-hall↗

arXiv2011

Role of electronic correlations in Ga

An extended around mean field (AMF) functional for less localized $p$ electrons is developed to quantify the influence of electronic correlations in $α$-Ga. Both the local density approximation (LDA) and generalized gradient approximation (GGA) are known to mispredict the Ga positional parameters. The extended AMF functional together with an onsite Coulomb interaction of $U_{\rm eff}=1.1$ eV, as obtained from constraint LDA calculations, reduces the deviations by about 20%. The symmetry lowering coming along with the electronic correlations turns out to be in line with the Ga phase diagram.

cond-mat.str-el↗

arXiv2011

The interplay between dopants and oxygen vacancies in the magnetism of V-doped TiO2

Density functional theory calculations indicate that the incorporation of V into Ti lattice positions of rutile TiO2 leads to magnetic V4+ species, but the extension and sign of the coupling between dopant moments confirm that ferromagnetic order cannot be reached via low-concentration doping in the non-defective oxide. Oxygen vacancies can introduce additional magnetic centres, and we show here that one of the effects of vanadium doping is to reduce the formation energies of these defects. In the presence of both V dopants and O vacancies all the spins tend to align with the same orientation. We conclude that V doping favours the ferromagnetic behaviour of TiO2 not only by introducing spins associated with the dopant centres but also by increasing the concentration of oxygen vacancies with respect to the pure oxide.

cond-mat.mtrl-sci↗

arXiv2007

Electronic structure of the zigzag spin-chain compound In$_2$VO$_5$

Band structure calculations within the local spin-density approximation are presented in order to investigate the electronic and magnetic properties of the zigzag spin-chain compound In$_2$VO$_5$. The essential structural feature of the system is a double chain of VO$_6$-octahedra, which leads to competing intrachain and interchain magnetic couplings. Frustration of the spin-chains is expected for the proposed antiferromagnetic ordering at low temperatures. However, the band calculations show that the experimental room temperature crystal structure is incompatible with antiferromagnetism. Both the intrachain and interchain coupling is found to be ferromagnetic.

cond-mat.str-el↗