Van der Waals electride: Toward intrinsic two-dimensional ferromagnetism of spin-polarized anionic electrons

Stable freestanding two-dimensional anionic electrons in YCl with extremely weak interlayer interaction

“…The ML YCl is composed of four atomic layers. The middle two 18,34 Bulk YCl with ZrCl-type structure (R% 3m) is formed by stacking the [YCl] along the c-axis in the ABC sequence and here the interlayer separation is denoted as d s which is about 3.09 Å (Fig. 1(c)).…”

“…The striking feature of the electronic structure for ML YCl is the highly dispersive bands in the range of À3 to À1 eV (labeled in green lines), which are mainly contributed by the AEs in the Y 6 octahedra. 18,34 In addition, a recent study suggests that the AEs in the Y 4 tetrahedra may also contribute to the weakly dispersive bands at about À1 eV to E F (labeled in purple lines) and thus the ferromagnetism may originate from the spinpolarized AEs. 34 These results clearly indicate that the AE states and ferromagnetism possibly related to these AE states are still preserved for the ML YCl, when compared to the bulk YCl.…”

Structural reconstruction and anisotropic conductance in 4f-ferromagnetic monolayer

“…It is noteworthy that most known 2D magnets, no matter experimentally verified or theoretical predicted, are based on spin moments of 3d electrons, whose orbitals are spatially localized with strong Hubbard correlation [8][9][10][11][12][13][14][15][16][17][18][19][20][21]. Apart from these transition metal compounds with unpaired 3d electrons, rare earth compounds with unpaired 4f electrons also play a significant role in modern magnets.…”

Electronic and topological properties of the van der Waals layered superconductor PtTe

“…This includes magnetism, topology, optoelectronics, and spintronics [1][2][3]. Monohalides with the ZrCl structure type have been rediscovered as interesting examples of such materials [4][5][6]. These compounds have a double layer of metal cations in a highly reduced formal oxidation state.…”

“…The double layer is bonded to halide anions above and below, producing slabs that stack together by van der Waals bonding to form a rhombohedral crystal structure. Materials with this structure have recently attracted attention as electrides [4], where electrons confined between the metal layers act as anions, and as 2D magnets when the cations are rare-earth metals [5,6]. It is also noteworthy that the rare-earth containing ZrCl-type materials may be stabilized by interstitial hydrogen [7].…”