Engineering of Magnetically Intercalated Silicene Compound: An Overlooked Polymorph of EuSi₂

Abstract

Silicene, a Si analogue of graphene, is suggested to become a versatile material for nanoelectronics. Being coupled with magnetism, it is predicted to be particularly suitable for spintronic applications. However, experimental realization of free-standing silicene and its magnetic derivatives is lacking. Fortunately, magnetism can be induced into silicene layers, in particular, by intercalation. Here, a successful synthesis of multilayer silicene intercalated by inherently magnetic Eu ions -a compound expected to exhibit both massless Dirac-cone states, as its Ca analogue, and a nontrivial magnetic structure -is reported. This new polymorph with EuSi 2 stoichiometry is epitaxially stabilized by continual replication of silicene layers employing Sr-intercalated multilayer silicene as a template. The atomic structure of the new compound and its sharp interface with the template are confirmed using electron diffraction, X-ray diffraction, and electron microscopy techniques. Below 80 K, the material demonstrates anisotropic antiferromagnetism coexisting with weak ferromagnetism. The magnetic state is accompanied by an anomalous behavior of magnetoresistivity.

Intrinsic Van Der Waals Magnetic Materials from Bulk to the 2D Limit: New Frontiers of Spintronics

“…Therefore, fabricating atomically thin magnetic devices with high‐density data storage and retention time is difficult. Earlier studies on fabricating 2D magnets mainly focused on reducing the thickness of 3D non‐vdW magnetic materials to several atomic layers through delicately controlled layer‐by‐layer growth or other specially designed methods . In parallel, both theoretical calculations and experimental results have verified that 2D magnetism is not restricted to those materials that exhibit magnetism in 3D form.…”

Emerging two-dimensional ferromagnetism in silicene materials

“…The borderline case is integration with the Si(111) substrate which is predicted to be possible by the 1 × 1 metal passivation leading to overlayer silicene preserving its Dirac cones 26 . Recently, we managed to produce epitaxial films on Si(111) of multilayer silicene stoichiometrically intercalated with active metals 27 , 28 , which could serve as parent compounds for 2D layer structures.…”

Magnetically intercalated multilayer silicene

“…In Ref. [10] we found an unconventional magnetoresistance and its temperature dependence in transport across silicene layers. Here, we study Hall resistance for the films.…”

“…Both CaSi 2 and SrSi 2 are nonmagnetic. To induce magnetic properties into silicene lattice we proposed a synthesis of multilayer silicene intercalated with inherently magnetic atoms [10]. We chose Eu because it is the most active among magnetic metals, the half-filled f-shell of Eu 2+ provides strong magnetic properties, and the isomorphism of Eu(II) and Sr compounds provides an opportunity for successful synthesis.…”

“…In Ref. [10] we thoroughly explored synthesis and properties of EuSi2 grown on SrSi 2 /Si(111) with silicene layers parallel to the surface. However, many unique properties of silicene lattice come from electric fields acting normal to silicene surface [3,5].…”