First-principles study of the electronic, magnetic and optical properties of Fe3Se4 in its monoclinic phase

Abstract In the present work, we have gained fundamental understanding of the physical properties of ferric selenide (Fe3Se4), an emerging ferrimagnetic material, via a systematic study of its structural, electronic, magnetic, optical and transport properties based on first-principles calculations. The analysis of the electronic band structure (with spin-orbit coupling taken into account) and density of states confirms its metallic behavior and reveals considerable hybridization of Fe-3d and Se-4p states near/at the Fermi level. With the predominant spin polarization on Fe sites, Fe3Se4 in its monoclinic phase favors a type-II ferrimagnetic ordering resulting in a total magnetic moment of 4.25 μ B per unit cell. The symmetry and charge analysis further suggests the tilting of Fe sub-lattice and the existence of interesting orbital-ordering due to the Jahn-Teller (JT) distortion. In addition, electron plasmonic peaks in the optical absorption spectra and unusual electrical and thermal transport properties are observed. These findings make Fe3Se4 as a potential candidate for a wide variety of applications in magnetism, spintronics, optoelectronics, and thermoelectrics.