Charge and Magnetic Orderings in the Triangular-Lattice Antiferromagnet InFe₂O₄

Abstract

InFe 2 O 4 belongs to the RFe 2 O 4 family where R is trivalent cation (R = In, Yb, Lu, Er, or Y). In the rhombohedral crystal structure of this compound as shown in Fig. 1 We succeeded in preparing high-quality InFe 2 O 4 belongs to the RFe 2 O 4 family where R is trivalent cation (R = In, Yb, Lu, Er, or Y). In the rhombohedral crystal structure of this compound as shown in Fig. 1, the double layers of FeO 5 bipyramids make two-dimensional triangular lattices and are separated by RO 6 octahedra. Since the numbers of Fe 2+ and Fe 3+ ions are equal in the triangular lattice, the coexistence of charge and magnetic frustrations is expected. However, despite the potential fascinating properties, InFe 2 O 4 had not been investigated well because of the difficulty in sample preparation.Mössbauer spectroscopy (γ // c) showed that Fe ions took average valence of 2.5+ above 250K, while it changed into 3+ and 2+ below 210K. Temperature dependence of the dielectric constant showed a peak around 230K, suggesting the charge ordering in Fe layer at this temperature.Mössbauer spectroscopy (γ // c) showed that Fe ions took average valence of 2.5+ above 250K, while it changed into 3+ and 2+ below 210K. Temperature dependence of the dielectric constant showed a peak around 230K, suggesting the charge ordering in Fe layer at this temperature. Magnetic measurement showed that InFe 2 O 4 magnetically ordered at 230K (Fig.2). The magnetization behavior below the ordering temperature suggests that this InFe 2 O 4 is a ferrimagnet. All experimental results indicate that charge and magnetic orderings in InFe 2 O 4 occur simultaneously.Magnetic measurement showed that InFe 2 O 4 magnetically ordered at 230K (Fig.2). The magnetization behavior below the ordering temperature suggests that this InFe 2 O 4 is a ferrimagnet. All experimental results indicate that charge and magnetic orderings in InFe 2 O 4 occur simultaneously.

Helical scattering signatures of strain and electronic textures in YbFe2O4from three-dimensional reciprocal-space imaging

“…The family of systems with general formula RFe 2 O 4 (R = Dy-Lu, and Y) has attracted significant interest, due to the possibility of high-temperature multiferroic behaviour arising from charge ordering [1][2][3][4][5][6][7][8][9][10] . Just above room temperature these systems undergo a metal-toinsulator (MI) transition, associated with sharp anomalies in the specific heat 4 , and on further cooling magnetic ordering sets in at around 250 K [11][12][13][14] .…”

Ferroelectricity from iron valence ordering in rare earth ferrites?

“…b) R 3+ ion size effect on cell volume and ratio of intralayer Fe−Fe distance a hex to bilayer thickness d b (c.f. c), compiled from [8,9,10,11,12,13,14]. c) Iron bilayers with one of the monoclinic cells, and the corresponding supercell.…”

Elemental substitution effects in multiferroic R Fe2O4 (R: rare earths)

“…It is also known that the localized Fe spins exhibit ferrimagnetic ordering below T N~2 50 K [2][3][4][5]; hence, RFe 2 O 4 belongs to a multiferroic system. The existence of the same type of charge ordering in the isostructural InFe 2 O 4 strongly suggests that this oxide is also ferroelectric [6].…”

“…Some of these substituted materials offer an advantageous property from the applied viewpoint. Namely, their dielectric losses were suppressed by the lowering of electron transfer, for example, resistivity of InFeCuO 4 is larger by ~10 [5][6] times than that of InFe 2 O 4 , while dielectric constant remains high (>~1000). Thus, properties of these materials are interesting to be investigated.…”