Atomic substitution provides a controlled route to engineer lattice dynamics in low-symmetry two-dimensional materials. Here, by combining polarization-resolved Raman spectroscopy and first-principles calculations, we investigate the evolution of phonon characteristics in CrSBr1−xClx (0≤x≤∼0.5) upon partial substitution of Br with Cl atoms. Progressive Cl substitution of Br induces systematic shifts of parent CrSBr out-of-plane Ag phonon modes and activates additional Raman features. These features persist across different polarization configurations and excitation energies, reflecting substitution-induced symmetry lowering and local lattice perturbations. Explicit supercell phonon calculations combined with Raman Γ-density-of-states simulations identify these features as symmetry-lowered descendants of parent modes arising from alloy disorder. Complementary strain-dependent calculations reveal that anisotropic lattice compression plays a key role in renormalizing Cr-S dominated phonons. Under near-resonant excitation, stimulated Raman scattering-like amplification remains observable with increasing Cl content, highlighting the resilience of anisotropic electron-phonon coupling in this system.
@article{arxiv.2601.13119,
title = {Robust phonon engineering and symmetry-selective lattice dynamics in CrSBr$_{1-x}$Cl$_{x}$},
author = {Satyam Sahu and Arsalan Hashemi and Mahdi Ghorbani-Asl and János Koltai and Jan Maňák and Bing Wu and Aljoscha Söll and Zdeněk Sofer and Mikko Karttunen and Arkady V. Krasheninnikov and Matěj Velický and Otakar Frank},
journal= {arXiv preprint arXiv:2601.13119},
year = {2026}
}