Thickness and pressure cooperatively modulate the transport properties in layered materials─particularly two-dimensional (2D) superconductivity─which are intrinsically governed by quantum confinement and anisotropic interactions. Here, through systematic investigation of thickness-dependent pressure-induced phenomena in black phosphorus, we reveal the mechanism by which dimensional confinement governs metallization and superconductivity via modulation of the electronic structure. Robust 2D superconductivity, observed in both few-layer samples and nanoflakes within the bulk, underscores quantum confinement as the fundamental origin of 2D superconductivity. Furthermore, the 3D-2D crossover in bulk highlights the critical role of weak interlayer coupling in stabilizing 2D superconducting behavior. Remarkably, quantum confinement dramatically enhances the critical field, with the in-plane critical field in 6-layer sample exceeding the Pauli limit due to enhanced spin–orbit scattering. These findings provide new insights into engineering superconducting dimensionality and properties via combined thickness and pressure control.
Cheng et al. (Thu,) studied this question.