Pressure-induced superconductivity in the van der Waals semiconductor violet phosphorus

TL;DR

This study reports the discovery of pressure-induced superconductivity in violet phosphorus, a van der Waals semiconductor, with distinct phase-dependent transition temperatures, highlighting its potential for electronic and optoelectronic applications.

Contribution

First demonstration of pressure-induced superconductivity in violet phosphorus with detailed phase diagram and comparison to black phosphorus.

Findings

Superconductivity appears at 2.75 GPa with Tc ~7 K

Tc remains stable across structural transition from M to R phases

Tc increases to ~10 K in the cubic phase above 15 GPa

Abstract

The van der Waals (vdW) semiconductor black phosphorus has been widely studied, especially after the discovery of phosphorene. On the contrary, its sister compound violet phosphorus, also a vdW semiconductor, has been rarely studied. Here we report the pressure-induced superconductivity in violet phosphorus up to $\sim$40 GPa. The superconductivity emerges at 2.75 GPa, which is well below the structural transition from monoclinic ($M$) to rhombohedral ($R$) structure at 8.5 GPa. The superconducting transition temperature ($T$$\rm_c$) shows a plateau of $\sim$7 K from 3.6 to 15 GPa, across the $M$ to $R$ structural transition, then jumps to another plateau of $\sim$10 K in the simple cubic ($C$) structure above 15 GPa. The temperature-pressure superconducting phase diagram of violet phosphorus is established, which is different from that of black phosphorus at low pressure. For black phosphorus, the superconductivity emerges until the structural transition from orthorhombic ($O$) to $R$ structure at $\sim$5 GPa, with a lower $T$$\rm_c$ than violet phosphorus. The pressure-induced superconductivity in violet phosphorus demonstrates its tunable electronic properties, and more electronics and optoelectronic applications are expected from this stable vdW semiconductor at ambient conditions.