New Pressure Stabilization Structure in Two-Dimensional PtSe<sub>2</sub>
Kai Jiang, Anyang Cui, Sen Shao, Jiajia Feng, Hongliang Dong, Bin Chen, Yanchao Wang, Zhigao Hu, Junhao Chu
Abstract
The frequency shifts and lattice dynamics to unveil the vibrational properties of platinum diselenide (PtSe2) are investigated using pressure-dependent polarized Raman scattering at room temperature up to 25 GPa. The two phonon modes Eg and A1g display similar hardening trends; both the Raman peak positions and full widths at half-maximum have distinct mutation phenomena under high pressure. Especially, the split Eg mode at 4.3 GPa confirms the change of the lattice symmetry. With the aid of the first-principles calculations, a new pressure stabilization structure C2/m of PtSe2 has been found to be in good agreement with experiments. The band structures calculations reveal that the new phase is a novel type-I Dirac semimetal. The results demonstrate that the pressure-dependent Raman spectra combined with theoretical predictions may open a new window for searching and controlling the phase structure and Dirac cones of two-dimensional materials.