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Novel Mott transitions in a nonisotropic two-band Hubbard model.
1Institut für Festkörperforschung, Forschungszentrum Jülich, 52425 Jülich, Germany. a.liebsch@fz-juelich.de
Physical Review Letters
|October 4, 2005
Summary
This study explores the Mott transition in a two-band Hubbard model, revealing two successive first-order transitions with Hund's rule coupling. Without spin-flip terms, the upper transition becomes continuous.
Area of Science:
- Condensed Matter Physics
- Quantum Many-Body Theory
Background:
- The Mott transition describes a metal-insulator transition in materials with strong electron-electron interactions.
- Understanding multi-band systems is crucial for accurately modeling complex electronic behaviors.
Purpose of the Study:
- Investigate the Mott transition in a two-band Hubbard model with varying subband widths.
- Analyze the influence of Hund's rule coupling on the phase diagram and transition types.
Main Methods:
- Employed dynamical mean-field theory (DMFT) combined with exact diagonalization.
- Studied the system's behavior as a function of temperature.
Main Results:
- The phase diagram exhibits two successive first-order transitions when full Hund's rule coupling is considered.
- In the absence of spin-flip and pair-exchange terms, the lower transition remains first-order, while the upper transition becomes continuous.
Conclusions:
- Hund's rule coupling significantly alters the nature of Mott transitions in multi-band systems.
- The interplay between bandwidths and interaction terms dictates the transition order.