Discoveries of two-dimensional (2D) magnetism originated from confined atomic layers in van der Waals (vdW) crystals provide an interesting arena for elucidating its fundamentals and enrich magneto-electric and quantum properties. However, a material that exhibits intrinsic 2D magnetism of interstitial electrons occupying layered space, as a root system of magnetic vdW crystals, remains obscure. In this work, 2D ferromagnetic vdW electride, [RECl]²⁺·2e⁻ (RE = Y and La) is reported with perfectly isolated ferromagnetic 2D blocks encompassing quasi-atomic electron layers. The ferromagnetism of the vdW electride with Curie temperature of 100 K originates from the spin-polarized quasi-atomic electrons with a substantial moment up to ∼0.91 Bohr magneton, which behave as magnetic elements in paramagnetic lattice framework. Invariable ferromagnetism at the monolayer limit strongly supports the 2D ferromagnetism of quasi-atomic electrons. These findings expand the variety of 2D magnetic crystals, providing a promising platform to study the emergent magnetism of low-dimensional electron phases.

源自范德华 (vdW) 晶体中受限原子层的二维 (2D) 磁性的发现为阐明其基本原理和丰富磁电和量子特性提供了一个有趣的领域。然而，作为磁性 vdW 晶体的根系，表现出占据层状空间的间隙电子的固有 2D 磁性的材料仍然不清楚。在这项工作中，二维铁磁 vdW 电子，[ RE Cl] ²⁺ ·2e ^- ( RE = Y 和 La) 报告了包含准原子电子层的完全隔离的铁磁 2D 块。居里温度为 100 K 的 vdW 电子化合物的铁磁性源于自旋极化准原子电子，其基本矩高达 ~0.91 玻尔磁子，其在顺磁晶格框架中表现为磁性元素。单层极限处的不变铁磁性强烈支持准原子电子的二维铁磁性。这些发现扩展了二维磁性晶体的种类，为研究低维电子相的涌现磁性提供了一个有前景的平台。