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Charge-orbital ordering and Verwey transition in magnetite
Horng-Tay Jeng1, G Y Guo, D J Huang
1Physics Division, National Center for Theoretical Sciences, Hsinchu 300, Taiwan. jeng@phys.uthu.edu.tw
Physical Review Letters
|November 5, 2004
Summary
Magnetite (Fe3O4) exhibits an insulating charge-orbital-ordered state below the Verwey transition, driven by on-site Coulomb interactions. This explains the insulating gap and charge ordering mechanisms in this material.
Area of Science:
- Condensed Matter Physics
- Materials Science
- Solid State Chemistry
Background:
- Magnetite (Fe3O4) undergoes a Verwey transition, leading to a change in its electronic properties.
- Understanding the electronic and magnetic states of magnetite is crucial for its applications.
Purpose of the Study:
- To investigate the charge and orbital ordering in magnetite below the Verwey transition temperature.
- To elucidate the fundamental mechanisms driving the insulating state and charge ordering.
Main Methods:
- Utilized local density approximation + Hubbard U (LDA + U) calculations.
- Performed band structure calculations to analyze electronic states.
Main Results:
- Revealed an insulating charge-orbital-ordered state in magnetite below the Verwey transition.
- Calculated charge ordering aligns with experimental observations.
- Identified t(2g) orbital ordering on the Fe2+ sublattice, primarily due to on-site Coulomb interaction.
Conclusions:
- The study clarifies the mechanism of charge ordering and the formation of the insulating gap in magnetite.
- Findings challenge Anderson's criterion regarding charge ordering in this material.
- On-site Coulomb interaction is identified as the primary driver for orbital ordering.