Pressure‐Induced Raman Anomaly and Emergent Superconductivity in Pyrite‐Type SiP ₂

Abstract Pyrite‐type ME 2 (M = electropositive metal, E = pnictogen or chalcogen) provides a large family of isostructural compounds characterized by unique bonding features and diverse physical properties that are of significant interest. In this study, the high‐pressure properties of pyrite‐type SiP 2 are investigated using electrical resistance measurements, Raman scattering, and synchrotron X‐ray diffraction. The results show an anomalous increase in the Raman intensity of the stretching modes of the P‐P dimer under high pressure. Notably, superconductivity emerges at 25.8 GPa, with the superconducting critical temperature ( T c ) rapidly rising to a maximum of 9.7 K at 35.1 GPa, exhibiting a direct correlation between superconductivity and vibrational modes in pyrite SiP 2 . Analysis of electron density maps from X‐ray diffraction reveals a charge transfer from Si ions to P 2 ions, which is believed to enhance polarizability, thereby facilitating the superconducting transition and substantially amplifying the P‐P stretching modes. This work underscores the critical role of bonding interactions in modulating the electronic and vibrational properties of pyrite‐type SiP 2 and encourages further investigation of other pyrite‐type compounds, as well as the application of pressure and Raman scattering in related studies.