Emerging two-dimensional ferromagnetism in silicene materials

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.

Coexisting structural phases in the catalytically driven growth of rock salt GdN

“…The last decade has seen an enormous expansion in studies of intrinsic ferromagnetic semiconductors, either 2D dimensional materials or thin films, which has opened a powerful new perspective in materials science and spintronics applications [1][2][3][4][5]. Within this scenario the fourteen mononitrides of the rare-earth (RENs) are of special interest as they are to date the only known series of intrinsic ferromagnetic semiconductors [1].…”

Quantitative determination of atomic buckling of silicene by atomic force microscopy

“…Silicene stands as the paradigm of buckled Xenes. Many silicene-related exotic properties have been predicted or realized, such as superconductivity (21), giant magnetoresistance (22), tunable topological phases (23), long-ranged 2D ferromagnetic ordering (24), or even a transistor (25). Since the seminal work of Vogt et al (2) where it was characterized on an Ag(111) surface, silicene has been grown only on a few other substrates, namely Ir(111) (26), ZrB2(0001) (27), MoS2(0001) (28), and Ru(0001) (29).…”

The Xenes Generations: A Taxonomy of Epitaxial Single‐Element 2D Materials

“…3) Epitaxy by intercalation (Figure c). Similar to deposition in item (1), X atoms are evaporated from a nearby source onto a matrix crystal that is either permeable to X atom, crossing through so as to form an Xene sheet in contact with a commensurate substrate (this is the case of silicene intercalated in between graphene and Ag(111), see Figure c top), or prone to form a Zintl crystal film where the Xene is a constitutive block in between two other metallic planes (this is the case of silicene planes incorporated in Zintl silicide structure of the MSi 2 form, where M is a rare‐Earth element like europium, strontium, and gadolinium, see Figure c bottom) …”

“…Alternatively, silicene was also identified as surface reconstruction in MoSi 2 substrates or as an intercalated plane in layered CaSi 2 compounds . In the latter fashion, silicene was isolated as a functionalized layer inside Zintl phase crystals such as SrSi 2 , GdSi 2 , and EuSi 2 aiming at 2D ferromagnetism, and intercalated in between a pregrown graphene layer and Ag(111) . Although most of the evidences about silicene epitaxy are concerned with metallic substrates, c‐Al 2 O 3 was currently reported to be the only insulating substrate supporting silicene based on theoretical and experimental facts .…”