Mott transition by an impulsive dielectric breakdown.
H Yamakawa1, T Miyamoto1, T Morimoto1
1Department of Advanced Materials Science, University of Tokyo, Chiba 277-8561, Japan.
Nature Materials
|August 22, 2017
Summary
Strong terahertz electric fields can induce a Mott transition in organic materials via dielectric breakdown. This purely electronic transition is faster and more coherent than laser-induced methods.
Area of Science:
- Condensed matter physics
- Materials science
- Quantum electronics
Background:
- Mott transitions, the change from insulator to metal, are typically induced by doping or photoirradiation.
- Organic materials and transition-metal compounds exhibit Mott transitions.
Purpose of the Study:
- To investigate a new pathway for inducing Mott transitions using strong electric fields.
- To explore the dynamics of Mott transitions induced by terahertz electric-field pulses.
Main Methods:
- Applied terahertz electric-field pulses to an ET-based compound, κ-(ET)₂Cu[N(CN)₂]Br.
- Observed the collapse of the Mott gap and analyzed spectral weight changes.
- Compared the transition speed and coherence with femtosecond laser-pulse irradiation.
Main Results:
- Impulsive dielectric breakdown induced a Mott transition, collapsing the Mott gap (∼30 meV) in ∼0.1 ps.
- Quantum tunneling produced doublon-holon pairs, indicated by nonlinear increases in low-energy spectral weights.
- The terahertz-induced metallization was faster and exhibited more electronic and coherent dynamics than laser-induced methods.
Conclusions:
- Strong terahertz-pulse irradiation is an effective method for achieving a purely electronic Mott transition.
- This approach offers a new pathway to study and understand the quantum nature of Mott transitions.
- The findings advance the understanding of electronic phase transitions in correlated materials.
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