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Ferromagnetism in doped excitonic insulators
1Room 1D-368, Bell Laboratories, Lucent Technologies, 700 Mountain Avenue, Murray Hill, New Jersey 07974, USA.
Physical Review Letters
|October 4, 2000
Summary
Doped excitonic insulators exhibit ferromagnetism when doped, driven by energy favoring intravalley condensation in hexaborides. This leads to inhomogeneous density and magnetization states at low temperatures.
Area of Science:
- Condensed matter physics
- Materials science
Background:
- Excitonic insulators are materials with unique electronic properties arising from electron-hole pairing.
- Recent experiments on hexaborides provide new insights into the behavior of these materials.
Purpose of the Study:
- To reinvestigate the theory of doped excitonic insulators.
- To explain recent experimental findings in hexaborides.
Main Methods:
- Theoretical analysis of doped excitonic insulators.
- Consideration of valley-degenerate band structures (X3, X'3).
Main Results:
- Intravalley condensation is energetically favored for specific band structures.
- Ferromagnetism arises upon doping due to kinetic energy quenching during the excitonic insulator-metal transition.
- The phase diagram reveals spatially inhomogeneous density and magnetization at low temperatures.
Conclusions:
- The study provides a theoretical framework explaining ferromagnetism in doped excitonic insulators.
- The findings are consistent with recent experimental observations in hexaborides.
- The predicted inhomogeneous states offer avenues for future research.