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Ferromagnetism versus Antiferromagnetism in Narrow-Band Systems: Competition between Quantum Geometry and Band
Haoyu Hu1,2, Oskar Vafek3, Kristjan Haule4
1University of Science and Technology of China, Department of Physics, Hefei, Anhui 230026, China.
Physical Review Letters
|July 10, 2026
Summary
Quantum geometry in narrow bands favors ferromagnetism, while band dispersion promotes antiferromagnetism. This competition creates tunable magnetic phases and rich spin phenomena in condensed matter systems.
Area of Science:
- Condensed matter physics
- Materials science
- Quantum magnetism
Background:
- Magnetism in narrow-band systems is complex, arising from electronic correlations, quantum geometry, and band dispersion.
- Both ferromagnetic and antiferromagnetic states are observed in narrow-band models, raising questions about their favored conditions.
Purpose of the Study:
- To develop a unified theoretical framework for investigating spin physics in narrow-band systems.
- To determine the conditions favoring ferromagnetic versus antiferromagnetic ordering.
Main Methods:
- Derivation of an effective spin model for narrow-band systems.
- Analysis of the interplay between non-atomic wave function (quantum geometry) and band dispersion.
Main Results:
- The non-atomic wave function (quantum geometry) generally favors ferromagnetic ordering.
- Band dispersion promotes antiferromagnetic correlations.
- The competition between these factors leads to tunable magnetic phases and diverse spin phenomena.
Conclusions:
- A unified framework is established for studying narrow-band magnetism.
- Quantum geometry and band dispersion are key competing factors determining magnetic ordering.
- The findings offer insights into controlling magnetic properties in materials.
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