Orbital and Bonding Anisotropy in a Half-Filled<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:msub><mml:mi>GaFeO</mml:mi><mml:mn>3</mml:mn></mml:msub></mml:math>Magnetoelectric Ferrimagnet

Kim, J.-Y.; Koo, Tae‐Yeong; Park, Jae‐Hyoung

doi:10.1103/physrevlett.96.047205

Cited by 150 publications

(89 citation statements)

References 20 publications

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“…However, the Fe 3+ single-ion anisotropy in CuFeO 2 can be as large as D » -0.2 meV with a puzzling downfall to D » -0.01 meV under a slight substitution Fe for Ga 3+ ions [17]. One of the most probable explanations for this unexpected anisotropy can be related with a markedly large and sensitive electric polarization of oxygen ions [18,19] which seems to be a specific property of delafossite structure as compared with many other oxides. The electric field induced O(sp)-hybridization accompanied with an effective off-center shift of the valence O2p-shell can result in a large orbital anisotropy through the anisotropic Fe 3d-O(2p)…”

Section: Neighbors (Nnn) Fe-o-fe and Next-next-nearest-neighbors (Nnnmentioning

confidence: 99%

⁵⁷Fe Mössbauer study of unusual magnetic structure of multiferroic 3R-AgFeO₂

Sobolev¹,

Rusakov²,

Moskvin³

et al. 2017

J. Phys.: Condens. Matter

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We report new results of a 57 Fe Mössbauer study of multiferroic 3R-AgFeO 2 powder samples performed in a wide temperature range, including two points, T N1 » 14 K and T N2 » 9 K, of magnetic phase transitions. At the intermediate temperature range, T N2 < T < T N1 , the 57 Fe Mössbauer spectra can be described in terms of collinear spin-density-waves (SDW) with the inclusion of many high-order harmonics, indicating that the real magnetic structure of this ferrite appears to be more complicated than a pure sinusoidally modulated SDW. The spectra at low temperatures, T < T N2 , consist of a Zeeman pattern with line broadenings and sizeable spectral asymmetry. It has been shown that the observed spectral shape is consistent with a transition to the elliptical cycloidal magnetic structure. An analysis of the experimental spectra was carried out under the assumption that the electric hyperfine interactions are modulated when the Fe 3+ magnetic moment rotates with respect to the principal axis of the EFG tensor and emergence of the strong anisotropy of the magnetic hyperfine field H hf at the 57 Fe nuclei. The large and temperatureindependent anharmonicity parameter, m » 0.78, of the cycloidal spin structure obtained from the experimental spectra results from easy-axis anisotropy in the plane of rotation of the iron spin.Analysis of different mechanisms of spin and hyperfine interactions in 3R-AgFeO 2 and its structural analogue CuFeO 2 points to a specific role played by the topology of the exchange coupling and the oxygen polarization in the delafossite structures.

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Section: Neighbors (Nnn) Fe-o-fe and Next-next-nearest-neighbors (Nnnmentioning

confidence: 99%

⁵⁷Fe Mössbauer study of unusual magnetic structure of multiferroic 3R-AgFeO₂

Sobolev¹,

Rusakov²,

Moskvin³

et al. 2017

J. Phys.: Condens. Matter

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“…The MCD ratio is estimated to be 2.8∶ −1, which gives a maximum spin moment 16. [24]; the features o and o 0 are due to the O h site up spin, and t is due to the T d site down spin as can be seen in Fig. 3.…”

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confidence: 88%

“…As the spins are fully aligned (eight up-and four down-spin Fe 3þ ions) [4,20], the ionic magnetic moment becomes 20μ B =f:u: (∼10% larger than the saturated moment M S at 10 K), and m o ¼ −0.38μ B =f:u: for H ab and m o ¼ þ0.09μ B =f:u: for H c , resulting in in-plane magnetic anisotropy. There exist only half-filled Fe 3þ (L ¼ 0, S ¼ 5=2) ions, and off-centering displacements can be considered as the origin of the nonvanishing m o as discussed in GaFeO 3 [24]. Indeed, one can find the off-centering distortions in the Y-type hexaferrite [19,25].…”

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confidence: 99%

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Magnetic Origin of Giant Magnetoelectricity in Doped Y-type HexaferriteBa0.5Sr1.5Zn2(
Noh
¹
,
Ko
²
,
Chun
³

et al. 2015
Phys. Rev. Lett.
28
0
5
0
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We investigated site-specific magnetic behaviors of multiferroic Ba 0.5 Sr 1.5 Zn 2 ðFe 1−x Al x Þ 12 O 22 using Fe L 2;3 -edge x-ray magnetic circular dichroism. The Al dopants mostly replace the Fe 3þ ions at octahedral (O h ) sites, which contribute unquenched angular momenta through off-centering displacements. This replacement greatly reduces the magnetic anisotropy energy to change the magnetic order from a helical to a heliconical type with enhanced magnetoelectric susceptibility (α ME ). The tetrahedral (T d ) Fe sites exhibit magnetic hysteresis distinguishable from that of the O h sites, especially at low magnetic fields. These results provide essential clues for the heliconical order with a giant α ME and multibit memory effects in the Al-doped Y-type hexaferrite. Multiferroic materials, in which magnetism and ferroelectricity coexist with a cross coupling, the so-called magnetoelectric (ME) effect, have been intensively studied experimentally and theoretically over the past decade due to their potential technological applications as nextgeneration multibit memory devices [1][2][3]. The ME effect was demonstrated in various multiferroic materials such as chromates, manganites, ferrites, etc. [1-6], and spiral, cycloidal, or noncollinear helical magnetic orders were known to be essential for a large ME effect [7][8][9][10][11]. Multiferroicity is well explained by an inverse Dzyaloshinskii-Moriya interaction [12,13] or a spin-current model [14]. However, most of the materials were recognized to face the difficulty of application barriers due to the low ME response, low ME temperature, and/or the requirement of a high magnetic field. Recently, hexaferrites with several different types have attracted much attention as candidates for possible multiferroic application materials with a giant ME susceptibility (α ME ) at a relatively high temperature [4,[15][16][17], and even nonvolatile multistate behaviors were demonstrated at room temperature [18]. Particularly in Y-type hexaferrites ðBa; SrÞ 2 Zn 2 Fe 12 O 22

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“…Two tetrahedral sublattices 6c 1 and 6c 2 are occupied by Fe and Zn. Similarly as in GaFeO 3 [3] the off-centricity may lead to a large orbital moment from which presumably the anisotropy originates. The effect of Al may then be either direct (decrease of the number of Fe, possesing large orbital momentum), or indirect by diminishing the off--centricity.…”

Section: Introductionmentioning

confidence: 99%