Friction force (f) usually increases with the normal load (N) macroscopically, according to the classic law of Da Vinci–Amontons (f = µN), with a positive and finite friction coefficient (µ). Herein near-zero and negative differential friction (ZNDF) coefficients are discovered in two-dimensional (2D) van der Waals (vdW) magnetic CrI₃ commensurate contacts. It is identified that the ferromagnetic–antiferromagnetic phase transition of the interlayer couplings of the bilayer CrI₃ can significantly reduce the interfacial sliding energy barriers and thus contribute to ZNDF. Moreover, phase transition between the in-plane (p_x and p_y) and out-of-plane (p_z) wave-functions dominates the sliding barrier evolutions, which is attributed to the delicate interplays among the interlayer vdW, electrostatic interactions, and the intralayer deformation of the CrI₃ layers under external load. The present findings may motivate a new concept of slide-spintronics and are expected to play an instrumental role in design of novel magnetic solid lubricants applied in various spintronic nano-devices.

As an excellent clean medium for hydrogen storage and fuel cell applications, the photolysis of ammonia via localized surface plasmon could be invoked as a promising route towards significantly reducing the temperature for conventional thermolysis. Here, we explore the underlying microscopic mechanism of ultrafast carrier dynamics in plasmon-mediated NH₃ photodecomposition at the single-molecular level using real-time time-dependent density functional theory. The NH₃ molecule adsorbed on the tip of archetypal magic metal clusters represented by tetrahedral Ag₂₀ and icosahedral Ag₁₄₇, splits within a hundred femtoseconds upon laser pulse illumination. We found that the splitting of the first N-H bond is dominated by the intramolecular charge transfer driven by localized surface plasmon. Surprisingly, the phase of laser pulse could modulate the dynamics of charge transfer and thus affect the plasmon-induced bond breaking. These findings offer a new avenue for NH₃ decomposition and provide in-depth insights in designing highly efficient plasmon-mediated photocatalysts.