Van der Waals electride: Toward intrinsic two-dimensional ferromagnetism of spin-polarized anionic electrons
Hyun Yong Song, Byung Il Yoo, Jin‐Ho Choi, Se-Hwang Kang, Joonho Bang, Wei Li, Chandani N. Nandadasa, Dinesh Thapa, Duhee Yoon, Myung Joon Han, Kyu Hyoung Lee, Kyu Hyoung Lee, Seong‐Gon Kim, Kimoon Lee, Kimoon Lee, Sung Wng Kim
Abstract
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.