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Frank Lechermann, Silke Biermann, and Antoine Georges
Centre de Physique Theorique, Ecole Polytechnique Palaiseau, France An understanding of the physics of strongly correlated multi-orbital electron systems is one of the key ingredients in order to describe a wide range of novel solid state compounds. The complex interplay of the crystal structure with the competition between the localized and the itinerant character of electrons in a manifestly multi-orbital case is giving rise to highly interesting physical phenomena. By combining the Dynamical Mean Field Theory (DMFT) with the Local Density Approximation (LDA) to Density Functional Theory, a powerful many-body approach is provided to tackle the given problem on a realistic level. Within LDA+DMFT we investigated the multi-orbital 3d1 system BaVS3 which is well-known for undergoing three distinct continuous phase transitions with decreasing temperature. In BaVS3, a structural transition at TS=240 K is followed by a metal-to-insulator transition (MIT) at TMIT=70 K. At around TX=30 K a final magnetic transition to an incommensurate antiferromagnetic ordered state seems to occur. The highlighted MIT appears to be accompanied by a charge density wave instability [1]. In our study, we concentrate mainly on the MIT and reveal the importance of the interorbital charge transfer between the 3d-orbitals of the V atoms induced by electronic correlations. From our LDA+DMFT investigations we are able to shed light on the underlying mechanism that drives BaVS3 into the insulating regime. [1] S. Fagot, P. Foury-Leylekian, S. Ravy, J.-P. Pouget, and H. Berger, Phys. Rev. Lett. 90, 196401 (2003). |