paper

Local Topological Markers in Odd Spatial Dimensions and Their Application to Amorphous Topological Matter

arXiv:2207.01646 · doi:10.1103/PhysRevLett.129.277601

Abstract

Local topological markers, topological invariants evaluated by local expectation values, are valuable for characterizing topological phases in materials lacking translation invariance. The Chern marker -- the Chern number expressed in terms of the Fourier transformed Chern character -- is an easily applicable local marker in even dimensions, but there are no analogous expressions for odd dimensions. We provide general analytic expressions for local markers for free-fermion topological states in odd dimensions protected by local symmetries: a Chiral marker, a local marker which in case of translation invariance is equivalent to the chiral winding number, and a Chern-Simons marker, a local marker characterizing all nonchiral phases in odd dimensions. We achieve this by introducing a one-parameter family of single-particle density matrices interpolating between a trivial state and the state of interest. By interpreting the parameter as an additional dimension, we calculate the Chern marker for the family . We demonstrate the practical use of these markers by characterizing the topological phases of two amorphous Hamiltonians in three dimensions: a topological superconductor ( classification) and a topological insulator ( classification).

13 pages, 3 figures; V2: Added supplemental material

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