Evidence of structural transition and spin-lattice coupling in antiferromagnetic MnSi₂Te₄

Layered van der Waals magnetic chalcogenides provide an important platform for exploring the interplay between lattice dynamics and magnetic correlations in low-dimensional systems. Here, we present a comprehensive temperature-dependent Raman spectroscopy study of a layered antiferromagnetic semiconductor MnSi_2Te_4, which exhibits large negative magnetoresistance. Several Raman modes exhibit pronounced and mode-selective anomalies in frequency, linewidth, and intensity near the antiferromagnetic Néel temperature (18.6 K) and a possible hidden phase transition temperature (100 K), whereby deviations from Curie-Weiss behavior in magnetic susceptibility were previously reported. Angle-resolved polarized Raman spectroscopy (ARPRS) measurements reveal distinct polarization-dependent responses for different Raman modes. These results indicate a nontrivial coupling between lattice vibrations and magnetic ordering in MnSi_2Te_4, and demonstrate Raman spectroscopy as an effective probe of structural phase transition and spin-lattice coupling in van der Waals magnets.