Emerging two-dimensional ferromagnetism in silicene materials

TLDR

Ultra‑compact spintronics drives research on magnetism in low‑dimensional materials, with recent advances in engineering 2D magnetism via defects, edges, adatoms, and proximity, yet intrinsic 2D ferromagnetism remained elusive until recent discoveries of out‑of‑plane magneto‑optical responses in Cr‑based layers. The study aims to produce layered silicene structures functionalized by rare‑earth atoms to explore 2D ferromagnetism. The authors use a bottom‑up approach to fabricate silicene layers functionalized with rare‑earth atoms, from bulk to monolayer. The study demonstrates that bulk silicene is antiferromagnetic, while ultrathin layers exhibit intrinsic in‑plane ferromagnetism with transition temperatures sensitive to low magnetic fields, observable in electron transport, establishing a robust class of 2D magnets compatible with silicon technology.

Abstract

The appeal of ultra-compact spintronics drives intense research on magnetism in low-dimensional materials. Recent years have witnessed remarkable progress in engineering two-dimensional (2D) magnetism via defects, edges, adatoms, and magnetic proximity. However, intrinsic 2D ferromagnetism remained elusive until recent discovery of out-of-plane magneto-optical response in Cr-based layers, stimulating the search for 2D magnets with tunable and diverse properties. Here we employ a bottom-up approach to produce layered structures of silicene (a Si counterpart of graphene) functionalized by rare-earth atoms, ranging from the bulk down to one monolayer. We track the evolution from the antiferromagnetism of the bulk to intrinsic 2D in-plane ferromagnetism of ultrathin layers, with its characteristic dependence of the transition temperature on low magnetic fields. The emerging ferromagnetism manifests itself in the electron transport. The discovery of a class of robust 2D magnets, compatible with the mature Si technology, is instrumental for engineering new devices and understanding spin phenomena.