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Metal-insulator transitions in the half-filled ionic Hubbard model
1Asia Pacific Center for Theoretical Physics, POSTECH, San 31 Hyoja-dong, Pohang 790-784, Korea. hatuan@iop.vast.ac.vn
Summary
This study investigates electronic phase transitions in the ionic Hubbard model, revealing a transition from band insulator to Mott insulator through a metallic state as electron repulsion increases. Critical points for these metal-insulator transitions are estimated.
Area of Science:
- Condensed Matter Physics
- Materials Science
Background:
- The ionic Hubbard model describes electronic interactions in materials with potential differences.
- Understanding phase transitions is crucial for designing novel electronic materials.
Purpose of the Study:
- To investigate electronic phase transitions in the half-filled ionic Hubbard model.
- To determine the critical points of metal-insulator transitions driven by electron correlation.
Main Methods:
- Utilizing the coherent potential approximation (CPA) for theoretical analysis.
- Comparing results with single-site dynamical mean-field theory and determinant quantum Monte Carlo simulations.
Main Results:
- Identified two distinct electronic phase transitions with increasing Coulomb repulsion (U) for a fixed ionic energy (Δ).
- Observed transitions from a band insulator to a metallic state, and then to a Mott insulator.
- Estimated the critical values for these correlation-driven metal-insulator transitions, denoted as U(c1)(Δ) and U(c2)(Δ).
Conclusions:
- The coherent potential approximation provides a reasonable description of the electronic phase transitions in the ionic Hubbard model.
- The findings align well with more computationally intensive methods, validating the CPA approach for this system.
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