Gauge-Field Extended k·p Method and Novel Topological Phases
1National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, China.
Physical Review Letters
|August 30, 2021
Summary
This study explores novel topological phases in artificial systems using Z2 gauge fields. It introduces a modified k·p method to analyze these unique crystalline phases, revealing new semimetal and nodal-line states.
Area of Science:
- Condensed Matter Physics
- Topological Materials
- Artificial Quantum Systems
Background:
- Topological artificial systems (acoustic/photonic crystals, cold atoms) initially simulated electronic topological phases.
- These systems possess unique features like spinless time-reversal symmetry and tunable Z2 gauge fields, necessitating new theoretical approaches.
Purpose of the Study:
- To explore novel topological phases unique to artificial systems with Z2 gauge fields.
- To develop a modified k·p method accounting for the projective representation of little co-groups and nontrivial translation relations.
Main Methods:
- Modification of the conventional k·p method to incorporate Z2 gauge fields.
- Analysis of two models: a rectangular π-flux model and a graphite model with interlayer π flux.
- Investigation of Fermi points, irreducible representations, and topological phase transitions.
Main Results:
- The Z2 gauge field fundamentally modifies the k·p method, leading to higher-dimensional irreducible representations and degenerate Fermi points.
- Demonstrated graphenelike semimetal phases in a rectangular π-flux model.
- Realized a second-order nodal-line semimetal phase with hinge helical modes in a graphite model.
Conclusions:
- The study opens new avenues for exploring topological phases unique to crystalline systems with gauge fields.
- Establishes a theoretical framework for analyzing these novel topological phases.
- Suggests physical realization possibilities using a bright-dark mechanism.
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