"Geometry-Enforced Topological Chiral Fermions in Amorphous Chiral Metals"
The recent recognition of a link between topological and structural chirality precipitated the experimental discovery of large families of ideal topological chiral (e.g. Weyl) semimetals (TSMs), such as B-20 RhSi, with dramatically long topological surface Fermi arcs and structural-chirality-dependent bulk topological chiral fermions, spin and orbital textures, and electromagnetic response [1,2]. However, outside of the limit of perfect translation symmetry, especially among the numerous experimentally accessible amorphous materials in nature, it remains an open question whether analogous non-crystalline chiral TSM states remain well-defined phases of matter, and whether they can similarly be predicted and identified. We present extensive analytic and numerical calculations demonstrating the existence of large families of chiral TSMs that persist under strong structural disorder whose bulk topology and angular momentum textures are tunable via the interplay of average symmetry and geometry [3]. To distinguish and generate new realizations of strongly disordered chiral fermions, we introduce an analytic approach grounded in symmetry group theory. We then introduce an amorphous Wilson loop numerical method to, for the first time, characterize chiral fermions with quantized Berry curvature fluxes in metals with 3D structural disorder. Our findings bridge the crystalline and strongly disordered regimes of chiral TSMs, and indicate a clear route towards engineering geometry-enforced topology in amorphous materials and metamaterials.
[1] G. Chang*, Xu*, BJW*, Sanchez*, Huang, Belopolski, T.-R. Chang, Zhang, Bansil, Lin, Hasan, PRL (2017)
[2] G. Chang*, BJW*, Schindler*, Sanchez, Belopolski, Huang, Singh, Wu, T.-R. Chang, Neupert, Xu, Lin, Hasan, Nature Materials (2018)
[3] Schirmann, Grushin*, BJW*, To Appear
