Even-Odd-Layer-Dependent Ferromagnetism in 2D Non-van-der-Waals CrCuSe.

Van der Waals (vdW) layered materials with strong magnetocrystalline anisotropy have attracted significant interest as the long-range magnetic order in these systems can survive even when their thicknesses is reduced to the 2D limit. Even though the interlayer coupling between the neighboring magnetic layers is very weak, it has a determining effect on the magnetism of these atomic-thickness materials. Herein, a new 2D ferromagnetic material, namely, non-vdW CuCrSe nanosheets with even-odd-layer-dependent ferromagnetism when laminated from an antiferromagnetic bulk is reported. Monolayer and even-layer CuCrSe exhibit the anomalous Hall effect and a significantly enhanced magnetic ordering temperature of more than 125 K. In contrast, the linear Hall effect exists in the odd-layer samples. Theoretical calculations indicate that the layer-dependent magnetic coupling is attributable to the orbital shift of the Cr atoms in the CrSe layers owing to the Cu-induced breaking of the centrosymmetry. Thus, this work sheds light on the exotic magnetic properties of layered materials that exhibit phenomena beyond weak interlayer interactions.