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Dielectric breakdown in spin-polarized Mott insulator
Zala Lenarčič1, Peter Prelovšek
1J. Stefan Institute, SI-1000 Ljubljana, Slovenia.
Physical Review Letters
|September 26, 2012
Summary
This study investigates Mott insulator dielectric breakdown using a Hubbard model. The threshold electric field for breakdown scales with the charge gap, showing a consistent mechanism across different spin polarizations.
Area of Science:
- Condensed Matter Physics
- Quantum Mechanics
Background:
- Mott insulators exhibit complex nonlinear responses to external electric fields.
- Dielectric breakdown in these materials is a critical phenomenon.
- Understanding the Hubbard model is key to describing correlated electron systems.
Purpose of the Study:
- To investigate the nonlinear dielectric breakdown of a Mott insulator under an external electric field.
- To analyze the phenomenon within a one-dimensional half-filled Hubbard model.
- To determine the relationship between the threshold electric field and the charge gap.
Main Methods:
- Utilized a one-dimensional half-filled Hubbard model.
- Employed analytical and numerical methods to evaluate the ground state decay rate.
- Studied the transition from nearly spin-polarized to unpolarized systems.
Main Results:
- The threshold electric field for dielectric breakdown scales with the charge gap as F(th)∝Δ(3/2).
- The decay rate of the ground state into excited holon-doublon pairs was accurately evaluated.
- A consistent breakdown mechanism was observed even for decreasing magnetization.
Conclusions:
- The dielectric breakdown in Mott insulators is governed by a mechanism dependent on the charge gap.
- This mechanism persists across a range of spin polarizations, including unpolarized systems.
- The findings provide insights into the nonlinear electrical properties of correlated electron systems.
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