2D Intrinsic Ferromagnets from van der Waals Antiferromagnets

Abstract

Intrinsically ferromagnetic 2D semiconductors are essential and highly sought for nanoscale spintronics, but they can only be obtained from ferromagnetic bulk crystals, while the possibility to create 2D intrinsic ferromagnets from bulk antiferromagnets remains unknown. Herein on the basis of ab initio calculations, we demonstrate this feasibility with the discovery of intrinsic ferromagnetism in an emerging class of single-layer 2D semiconductors CrOX (CrOCl and CrOBr monolayers), which show robust ferromagnetic ordering, large spin polarization, and high Curie temperature. These 2D crystals promise great dynamical and thermal stabilities as well as easy experimental fabrication from their bulk antiferromagnets. The Curie temperature of 2D CrOCl is 160 K, which exceeds the record (155 K) of the most-studied dilute magnetic GaMnAs materials, and could be further enhanced by appropriate strains. Our study offers an alternative promising way to create 2D intrinsic ferromagnets from their antiferromagnetic bulk counterparts and also renders 2D CrOX monolayers great platform for future spintronics.

Strain-induced phase transition in CrI3 bilayers

“…The Ising model is widely used to describe the magnetic coupling of low-dimensional magnetic systems [42][43][44] . Herein, we numerically solve the Ising model to calculate the Curie temperature T C .…”

Various Structures of 2D Transition‐Metal Dichalcogenides and Their Applications

“…MoS 2 has been utilized to availably improve the performance of perovskite solar cells . Recently, intrinsic magnetism in 2D materials was found by researchers, which will promote feasible applications in spintronic devices and storage devices . Theoretically, there are 56 kinds of 2D materials that have ferromagnetic or antiferromagnetic properties .…”

“…[50] Recently, intrinsic magnetism in 2D materials was found by researchers, which will promote feasible applications in spintronic devices and storage devices. [51][52][53] Theoretically, there are 56 kinds of 2D materials that have ferromagnetic or antiferromagnetic Small Methods 2018, 2, 1800094 Figure 1. a) There are more than 40 different TMDs that can form a stable structure. The transition metals are highlighted in red and chalcogens are highlighted in yellow in the periodic table of the elements.…”

Super-exchange theory for polyvalent anion magnets

“…In the present work, we take recently proposed 2D magnetic CrOCl [18] as an example to theoretically analyze the SEI of polyvalent anion materials (valence state −2 for O 2− , −1 for Cl − ), which we call extended super-exchange theory (ESET). ESET firstly gives the valid electronic state of cation in specific super-exchange path, namely superposed d d…”