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Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
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Topological Phases without Crystalline Counterparts.
Dániel Varjas1,2, Alexander Lau2, Kim Pöyhönen1,2
1QuTech, Delft University of Technology, P.O. Box 4056, 2600 GA Delft, Netherlands.
Physical Review Letters
|November 26, 2019
Summary
We discovered a new type of topological phase protected by quasicrystalline symmetry, hosting Majorana zero modes at the corners of octagonal samples. This reveals topological phases beyond crystalline systems.
Area of Science:
- Condensed Matter Physics
- Topological Matter
- Quasicrystalline Physics
Background:
- Higher-order topological phases exhibit unique properties localized at boundaries of lower dimensionality.
- Quasicrystalline symmetries, unlike periodic crystal symmetries, offer novel platforms for topological phenomena.
- Topological superconductors host exotic excitations like Majorana zero modes.
Purpose of the Study:
- To construct and analyze a two-dimensional higher-order topological phase protected by quasicrystalline eightfold rotation symmetry.
- To investigate the existence and properties of Majorana zero modes in such a system.
- To identify the bulk topological invariant protecting these localized modes.
Main Methods:
- Development of a tight-binding model for a superconductor on an Ammann-Beenker tiling.
- Introduction of Hamiltonians generated by a local rule for analyzing bulk topological properties.
- Identification of a Z_{2} bulk topological invariant.
Main Results:
- Localized Majorana zero modes were found at the corners of an octagonal sample.
- A Z_{2} bulk topological invariant was identified, confirming the protection of corner modes.
- The study demonstrates topological phases protected by non-crystalline symmetries.
Conclusions:
- A novel higher-order topological phase protected by quasicrystalline symmetry has been realized.
- The findings confirm the existence of Majorana zero modes in this system.
- This work expands the understanding of topological phases beyond conventional crystalline systems.
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