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TT: Fachverband Tiefe Temperaturen

TT 34: Correlated Electrons: Metal-Insulator Transition 2

TT 34.2: Vortrag

Donnerstag, 28. Februar 2008, 14:15–14:30, H 2053

Magnetic Moment Collapse-Driven Mott Transition in MnO — •Jan Kunes¹, Alexey V. Lukoyanov², Vladimir I. Anisimov³, Richard T. Scalettar⁴, and Warren E. Pickett⁴ — ¹Center for Electronic Correlations and Magnetism, University of Augsburg, Augsburg 86135 — ²Ural State Technical University-UPI, 620002 Yekaterinburg, Russia — ³Insitute of Metal Physics, Russian Academy of Sciences, 620041 Yekaterinburg, Russia — ⁴Department of Physics, University of California, Davis 95616, U.S.A.

We employ a combination of numerical density-functional bandstructure and dynamical mean-field theory to study the evolution of electronic properties of MnO under pressure. Motivated by recent high-pressure experiments we investigate the relationship between high-spin to low-spin transition (moment collapse), insulator-to-metal (Mott) transition and isostructural volume collapse. Our results, which closely resemble the experimental observations, demonstrate that the moment collapse and Mott transition happen simultaneously and that the crystal-field splitting, not the band broadening, is the driving force behind the transition. The Mott transition turns out to be essentially a consequence of local atomic states, high-spin or low-spin, placing different constraints on the electron propagation resulting in insulating or metallic ground states respectively. Energy vs volume curve shows that the specific volume changes discontinuously at the transition. The study represents a significant progress over previous theories which did not provide a reliable picture of the Mott transition.