Si-related ferrimagnetic material consisting of Eu and Fe layers

In order to explore Si-related spintronic materials, we use a full-potential density-functional-theory method to study electronic structure and magnetic properties of EuFe₂Si₂ with the layered ThCr₂Si₂ structure. Our comparative optimization investigation among 25 magnetic configurations reveals that its ground state phase is a ferrimagnet, in which the spins in both of Eu and Fe layers are aligned ferromagnetically, but the Eu spins are aligned antiferromagnetically with the Fe spins. This is very different from the striped antiferromagnetic ground state for the Fe spins in FeAs-based materials. The filled Eu 4f bands in the majority-spin channel, very flat, are just below the Fermi level and the Fe 3d bands cover an energy range of 4 eV astride the Fermi level. The Eu atom is ionic and contributes a moment of nearly 7μ_B, and Fe is bonded strongly with Si, which results in a low-moment state for Fe. Our results are of interest to explore the physical properties of the Fe-based materials, and can stimulate further effort to seek useful Si-related spintronic materials.