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Updated: Jan 3, 2026

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses
Published on: June 7, 2018
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.
Abstract:
We construct a two-dimensional higher-order topological phase protected by a quasicrystalline eightfold rotation symmetry. Our tight-binding model describes a superconductor on the Ammann-Beenker tiling hosting localized Majorana zero modes at the corners of an octagonal sample. In order to analyze this model, we introduce Hamiltonians generated by a local rule, and use this concept to identify the bulk topological properties. We find a Z_{2} bulk topological invariant protecting the corner modes. Our work establishes that there exist topological phases protected by symmetries impossible in a crystal.
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