Weak Ferromagnetism in the FeCr2O4 Semiconductor Spinel with Half-Metallic Feature in the Ground State

Abstract

Materials with multifunctional properties are currently being studied for countless technological applications. In the present work, an experimental and theoretical study of the iron-chromite spinel FeCr 2 O 4 produced by the solid-state reaction technique is reported. Structural analysis from x-ray diffraction experiments revealed the crystallization of the material into a cubic structure and morphological and compositional studies showed the granular character, with nanometric and micrometric dimensions whose compositions are as expected from its chemical stoichiometry. Optical characterization reveals semiconducting behavior with bandgap 1.52 eV and the magnetic response shows weak ferromagnetic character at room temperature. The density of electronic states in the ground state evidences characteristic semiconducting for one spin polarization and conducting for the other close to the Fermi level, which is compatible with a half-metallic behavior with magnetic moment of 2.0 µ B per unit cell.

Liquid‐Phase Exfoliation of Nonlayered Non‐Van‐Der‐Waals Crystals into Nanoplatelets

“…Based on the electronic properties we have also observed that most of the material exfoliated are semiconductors, such as α‐WO 3 , [ 64,119 ] LiMn 2 O 4 , [ 65,120 ] β‐B, [ 121,122 ] α‐Fe 2 O 3 , [ 68,123 ] FeCr 2 O 4 , [ 70,124 ] FeTiO 3 , [ 69,125 ] MnTe, [ 71 ] PbS, [ 75,126 ] α‐FeO(OH), [ 127 ] SiC, [ 76 ] B 4 C, [ 128 ] FeS 2 , [ 79,123 ] Ge, [ 129 ] Si, [ 129 ] TiC, [ 130 ] and WC. [ 131 ] This is very important because all these materials are fundamentally different, as semiconductors such as silicon, germanium, etc.…”

Enhancing thermoelectric performance via relaxed spin polarization upon magnetic impurity doping

“…in magnetic systems, which opens up many possibilities in magnetism-mediated TE materials. In future research, not only half metallic systems such as spinel ferrites (FeCr 2 O 4 and VFe 2 O 4 ), [66][67][68] but nonmagnetic semiconductors doped with magnetic impurities, such as Cr x Sb 2−x Te 3 , 69 Fe x Bi 2−x Te 3 70 and Fe x (Bi, Sb) 2−x Te 3 71 which possess weak ferromagnetism and a low carrier concentration, could be promising systems to implement the proposed strategy.…”

“…We believe that the spin polarization relaxation via the introduction of antiferromagnetic coupling between host magnetic ions and magnetic impurities can be utilized as a general strategy to enhance the Seebeck coefficient in magnetic systems, which opens up many possibilities in magnetism-mediated TE materials. In future research, not only half metallic systems such as spinel ferrites (FeCr 2 O 4 and VFe 2 O 4 ), 66–68 but nonmagnetic semiconductors doped with magnetic impurities, such as Cr x Sb 2− x Te 3 , 69 Fe x Bi 2− x Te 3 70 and Fe x (Bi, Sb) 2− x Te 3 71 which possess weak ferromagnetism and a low carrier concentration, could be promising systems to implement the proposed strategy.…”