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

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 EuSi2 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.