2025/12/18 by Parlak, Selçuk, Kumar, Abhishek, Li, Runhan +2
#FOS: Physical sciences #Materials Science (cond-mat.mtrl-sci)
paper · doi:10.48550/arxiv.2512.16377
Recently, two unusual features were theoretically predicted for the Raman response of out-of-plane phonons in magnetic two-dimensional materials hosting massive Dirac fermions. First, the phase difference between certain Raman tensor elements was found to be quantized to ± π/2, sensitive only to the sign of the Dirac fermion mass. Second, a selection rule was identified in the Raman intensity under circularly polarized light, which generalizes the well-known optical valley selection rule. These predictions were based on a low-energy effective model in the continuum approximation. Here, we test the robustness of those results for more realistic theoretical approaches. First, we calculate the Raman tensor for an electronic tight-binding model on a honeycomb lattice with broken time-reversal and inversion symmetries. Second, we compute the Raman tensor from density functional theory (DFT) for a monolayer of ferromagnetic 2H-RuCl2. Both calculations corroborate the analytical results found in the continuum model, thereby theoretically confirming the peculiar behaviour of the Raman tensor for two dimensional massive Dirac fermion systems.