Physicists have identified Fermi arc interference on the low-symmetry (103) surface of the Weyl semimetal NdAlSi, according to peer-reviewed research published on August 13, 2026, in Nature Communications.
Using angle-resolved photoemission spectroscopy, the researchers observed loop-like Fermi-arc connectivity and replica modulations that do not appear on high-symmetry surfaces. These topological surface states reconstruct when Fermi arcs from phase-shifted bulk-zone projections overlap and hybridize, creating connectivity patterns specific to low-symmetry crystal facets.
The study found that these spectral patterns stem from incomplete bulk projections and multi-cell interference governed by a least-common-multiple framework. Density functional theory and Green’s-function calculations guided by this framework reproduced both the reconstructed periodicity and the primary replica structure observed in the spectra.
The measurements resolve an apparent bulk-boundary correspondence paradox on low-symmetry surfaces by showing how boundary spectra can be modeled across complex facets. Experiments were carried out at beamline BLOCH at MAX IV Laboratory in Sweden, beamline I05 at Diamond Light Source in the United Kingdom, and the Synergetic Extreme Condition User Facility. The research team included co-lead authors Cong Li and Zhilong Yang, alongside collaborators from the Chinese Academy of Sciences, KTH Royal Institute of Technology, the University of Science and Technology Beijing, and Politecnico di Milano.
