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Topological phase transition induced by band structure modulation in a Chern insulator
Sayan Mondal1, Priyadarshini Kapri2, Bashab Dey2
1Department of Physics, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India.
Journal of Physics. Condensed Matter : an Institute of Physics Journal
|February 19, 2021
Summary
This study investigates how changing electron hopping in a Chern insulator affects its topological properties. We found a phase transition from a topological to a trivial insulator at a specific hopping parameter, marked by a semi-Dirac point.
Area of Science:
- Condensed Matter Physics
- Topological Materials
- Electronic Band Structure
Background:
- Chern insulators exhibit non-trivial topological properties characterized by a non-zero Chern number.
- Honeycomb lattices are crucial platforms for realizing topological phases due to their unique band structures.
Purpose of the Study:
- To systematically investigate the evolution of topological properties in a Chern insulator.
- To understand the impact of varying nearest-neighbor hopping parameters on electronic band structures and topological phases.
- To identify phase transitions and their characteristics in a tunable Chern insulator model.
Main Methods:
- Theoretical modeling of electron hopping on a honeycomb lattice.
- Analysis of electronic band structures, including Dirac cones and semi-Dirac dispersions.
- Calculation of the Berry curvature and Chern number to map topological phases.
- Investigation of edge state behavior and anomalous Hall conductivity.
Main Results:
- A transition from a Chern insulator to a trivial insulator was observed as the hopping parameter (t1) was varied.
- A gapless semi-Dirac dispersion emerged at t1 = 2t, acting as a critical point for the phase transition.
- The Chern number phase diagram revealed shrinking topological lobes that vanished beyond t1 = 2t.
- Anomalous Hall conductivity plateaus vanished, and chiral edge states merged with bulk bands near the M point.
Conclusions:
- A clear phase transition from a topological to a trivial insulating phase occurs at the semi-Dirac point.
- The observed transition is robustly supported by the vanishing Hall conductivity and edge state behavior.
- Tuning hopping parameters provides a viable route to control and switch topological properties in materials.
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