Flat-band ferrimagnetism in the edge-centered honeycomb antiferromagnet: From harmonic flat magnon to broad continuum
The study examined how a 2:3 sublattice imbalance in an edge-centered honeycomb antiferromagnet creates a single-particle flat band and stabilizes a ferrimagnetic ground state. While linear spin-wave theory predicts a sharp flat magnon, quantum fluctuations transform this into a broad, weakly dispersive continuum, showing that spectral weight organizes rather than forming protected quasiparticles.