Correlation-driven organic 3D topological insulator with relativistic fermions

Area of Science:

• Condensed-matter physics
• Materials science
• Quantum phenomena

Background:

• Strong electron correlation drives novel topological phenomena, distinct from spin-orbit coupling.
• Topological insulator (TI) states are a key focus in condensed matter physics.
• Organic materials offer unique platforms for exploring electronic properties.

Purpose of the Study:

• To investigate a 'correlation-driven' topological insulator (TI) state.
• To explore functionalities arising from electron correlation in organic systems.
• To identify new topological phenomena and phases in novel materials.

Main Methods:

• Experimental realization of a correlation-driven TI state in α-(BETS)₂I₃.
• Analysis of temperature and field dependences of resistance.
• Observation of topological surface states and chiral anomaly.
• Investigation of topological phase switching using DC current.

Main Results:

• A three-dimensional TI state was identified in α-(BETS)₂I₃ at low temperatures.
• Evidence of topological surface states and chiral anomaly was observed.
• A unique topological phase switching between TI and non-equilibrium Dirac semimetal states was demonstrated via DC current.
• The material exhibits functionalities characteristic of correlation-driven TI states.

Conclusions:

• Correlation-driven TIs in organic systems are promising for electronic devices.
• These materials provide a platform for discovering new topological phenomena and phases.
• The observed phase switching highlights unique functionalities of correlation-driven topological states.