Biomedical subjects

E Müller-Hartmann

Publications and source records attributed to E Müller-Hartmann.

9 recordsLinked to original sources

PubMed2003

Orbital switching and the first-order insulator-metal transition in paramagnetic V2O3.

The first-order metal-insulator transition (MIT) in paramagnetic V2O3 is studied within the ab initio scheme LDA+DMFT, which merges the local density approximation (LDA) with dynamical mean field theory (DMFT). With a fixed value of the Coulomb U=6.0 eV, we show how the abrupt pressure driven MIT is understood in a new picture: a pressure-induced decrease of the trigonal distortion within the strong correlation scenario (which is not obtained within LDA). We find good quantitative agreement with (i) switch of the orbital occupation of (a(1g),e(pi)(g1),e(pi)(g2)) and the spin state S=1 across the MIT, (ii) thermodynamics and dc resistivity, and (iii) the one-electron spectral function, within this new scenario.

Journal Article↗

PubMed2003

Orbital Kondo effect in CrO2: a combined local-spin-density-approximation dynamical-mean-field-theory study.

Motivated by a collection of experimental results indicating the strongly correlated nature of the ferromagnetic metallic state of CrO2, we present results based on a combination of the actual band structure with dynamical-mean-field theory for the multiorbital case. In striking contrast to LSDA(+U) and model many-body approaches, much better semiquantitative agreement with (i) recent photoemission results, (ii) domain of applicability of the half-metal concept, and (iii) thermodynamic and dc transport data is obtained within a single picture. Our approach has broad applications for the detailed first-principles investigation of other transition metal oxide-based half-metallic ferromagnets.

Journal Article↗

PubMed2001

Origin of the non-fermi liquid behavior of SrRuO3.

Motivated by the unusual features observed in the transport properties of the ferromagnetic "bad metal" SrRuO3, we construct a model incorporating essential features of the realistic structure of this nearly cubic material. In particular, we show how the t2g orbital orientation in the perfectly cubic structure determines the peculiar structure of the hybridization matrix, and demonstrate how the local non-Fermi liquid features arise when interactions are switched on. We discuss the effects of the slight deviation from the cubic structure qualitatively. The model provides a consistent explanation of the features observed recently in the optical response of SrRuO3.

Journal Article↗

PubMed1996