Layer-number-parity-dependent abnormal magnetic ordering in few-layer CrI3 on N-face AlN substrate

The research about two-dimensional van der Waals magnetic materials has advanced the breakthroughs in ultrathin magnetic devices. We experimentally demonstrate that a single-crystal N-face AlN polar substrate can program layer-number-parity-dependent magnetic multistates and their evolution sequence in few-layer CrI₃. In odd-layer samples, as 5L-CrI₃/AlN, when μ₀H sweeps from 3 to -3 T, the reflective magnetic circular dichroism signal evolves through distinct magnetic multistates (+ 5 → -1 → +1 → -5), where +1 corresponds to the moment of a spin-up monolayer. Thereby, we vertically program novel magnetic ground states and their evolution sequence via a simplified heterointerface. Our first-principles calculations attribute this effect to interfacial hole doping: it globally reconfigures the magnetic ground state of odd-layer CrI₃ to a novel ferrimagnetic order, and spatially differentiates the interlayer exchange coupling and magnetic anisotropy between the surface/interfacial and interior layers. Our work advances the practical integration and design of two-dimensional magnetic devices with tailored functionalities.