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Quantum phase transitions of topological insulators without gap closing
1Institute for Theoretical Physics, TU Dresden, 01062 Dresden, Germany.
Summary
Topological insulators exhibit unique phase transitions. Certain topological insulators, like the chiral Chern insulator, resist perturbations, while others transition to trivial phases without closing their bulk gap.
Area of Science:
- Condensed matter physics
- Quantum materials science
Background:
- Topological insulators (TIs) are materials with unique electronic properties characterized by a bulk band gap and conducting surface states.
- Perturbations can break fundamental symmetries, potentially driving topological phases towards trivial states.
- Chern insulators and time-reversal invariant topological insulators are key examples of topological phases.
Purpose of the Study:
- To investigate the impact of perturbations that break particle-number conservation or time-reversal symmetry on two-dimensional Chern insulators and time-reversal invariant topological insulators.
- To understand the mechanisms and conditions under which these topological phases undergo quantum phase transitions.
- To explore the role of additional symmetries in protecting topological properties.
Main Methods:
- Theoretical analysis of two-dimensional topological insulators under symmetry-breaking perturbations.
- Investigation of quantum phase transitions driven by perturbations that introduce trivial mass terms.
- Examination of bulk-gap closing and gapless transitions in different topological phases.
Main Results:
- Chiral Chern insulators are robust against perturbations that break particle-number conservation.
- The [Formula: see text] topological insulator transitions to a trivial phase without bulk-gap closing when subjected to symmetry-breaking perturbations.
- These transitions can be prevented by additional U(1) symmetries, such as spin conservation.
Conclusions:
- The stability of topological phases against perturbations depends on the specific topological invariant and the nature of the symmetry breaking.
- The absence of bulk-gap closing during transitions in certain topological insulators highlights novel mechanisms for topological phase changes.
- Understanding these transitions is crucial for designing and utilizing topological materials in future electronic devices.
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