Pressure-induced superconducting state and lifshitz transition in the van der Waals violet phosphorus

Violet phosphorus (VP) has recently attracted attention as a promising two-dimensional van der Waals material due to its unique physicochemical properties and broad application potential. However, its behavior under extreme conditions, particularly high-pressure structural evolution and superconductivity, remains insufficiently understood. In this study, we systematically investigate the high-pressure behavior of VP using in situ synchrotron X-ray diffraction in combination with electrical transport measurements. Our results provide compelling experimental evidence for a complex structural evolution, with VP transitioning from its ambient monoclinic (M) phase to an rhombohedral (A7) phase and ultimately to a simple cubic (C) phase. Simultaneously, a pressure-induced semiconductor-to-metal transition is observed at a critical pressure of ∼8.0 GPa, followed by the emergence of superconductivity above 9.0 GPa. Remarkably, the superconducting critical temperature (T_c) exhibits pronounced non-monotonic pressure dependence, valley-shaped pressure dependence before reaching a maximum of ∼10.8 K at ∼35.0 GPa. First-principles calculations attribute this unusual behavior to two nearly concurrent Lifshitz transitions occurring around 25–30 GPa in the simple cubic phase, which substantially modify the Fermi surface topology and electron–phonon coupling. Our findings provide key insights into the high-pressure electronic phases of VP and establish a foundation for exploring its tunable electronic and superconducting properties.