Charge disproportionation and interchange transitions in twelve-layer 
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Tan, Zhenhong; Romero, Fabio Denis; Saito, Takashi; Goto, Masato; Patiño, Midori Amano; Koedtruad, Anucha; Kosugi, Yoshihisa; Chen, Wei-Tin; Chuang, Yu‐Chun; Sheu, Hwo Shuenn; Attfield, J. Paul; Shimakawa, Yuichi

doi:10.1103/physrevb.102.054404

Cited by 12 publications

(17 citation statements)

References 28 publications

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“…The actual spin structures remain to be determined by neutron diffraction. Interestingly, the magnetic transition temperatures are lower than those of the 6H- (180 K) and 12R-type (280 K) hexagonal BaFeO 3 due to the two-dimensionality of the magnetic structure isolated by nonmagnetic Ge-tetrahedral layers. , …”

Section: Resultsmentioning

confidence: 90%

“…The significant changes in IS for Fe2 and Fe3 from those at 300 K show possible charge disproportionation within the Fe 3 O 12 trimers. Judging from the IS values compared to those in the 12R BaFeO 3 ; however, the charge disproportionation from Fe 4+ to Fe 3+ and Fe 5+ appears to be incomplete and can be described as Fe2 4+ + 2Fe3 4+ → Fe2 (4+2δ)+ + 2Fe3 (4−δ)+ . The Fe ions at the corner-sharing Fe1 site remain in the +3 state and do not participate in the charge disproportionation.…”

Section: Resultsmentioning

confidence: 91%

“…Actually, the high-pressure-synthesized 12-layer BaFeO 3 showed successive charge disproportionation and intersite charge transfer transitions on cooling. In the transition at 50 K, the interchange between the charge-disproportionated Fe 3+ and Fe 5+ occurred in the face-sharing trimers . In this study, we substitute some of the Fe 4+ in BaFeO 3 with nonmagnetic Ge 4+ .…”

Section: Introductionmentioning

confidence: 85%

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Layered Hexagonal Perovskite Oxides 21R Ba₇Fe₅Ge₂O₂₀ and 12H Ba₆Fe₃Ge₃O₁₇

et al. 2021

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Two hexagonal-perovskite-structure oxides, 21R Ba7Fe5Ge2O20 and 12H Ba6Fe3Ge3O17, were obtained by synthesis with a high-pressure and high-temperature technique. The Fe-containing hexagonal-perovskite-structure units are sandwiched by nonmagnetic GeO4 tetrahedral layers in the structures, and thus both compounds show two-dimensional ferrimagnetic behaviors due to intra- and interunit magnetic interactions. 21R Ba7Fe5Ge2O20 has the ionic formula Ba7Fe12 3+Fe24+Fe32 4+Ge42 4+O20 at room temperature, and unusually high valence Fe4+ in the trimers undergoes charge disproportionation, Fe24+ + 2Fe34+ → Fe2(4+2δ)+ + 2Fe3(4−δ)+, at low temperatures. In contrast, 12H Ba6Fe3Ge3O17 with ionic formula Ba6Fe12 3+(Fe20.5 4+Ge20.5 4+)2Ge32 4+O17 does not show a charge transition.

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Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 85%

See 1 more Smart Citation

Layered Hexagonal Perovskite Oxides 21R Ba₇Fe₅Ge₂O₂₀ and 12H Ba₆Fe₃Ge₃O₁₇

et al. 2021

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“…THz-TDS is a technique that experimentally characterizes short electromagnetic pulse measurements. The transmission coefficient t(ω) is defined as the ratio of the transmitted amplitude A(ω) through the sample to the amplitude A Ref (ω) without the sample after calculating the FFT of both E(t) and E Ref (t), as shown in Equation (1). In this paper, the amplitude |t(ω)| was used as the transmittance t(ω).…”

Section: Methodsmentioning

confidence: 99%

“…Recent developments in the fields of photoinduced spin reorientation, vectorial control of magnetization by light, antiferromagnet-ferromagnet phase transitions induced by light, and optical modification of exchange interactions have led to renewed interest in antiferromagnetic materials because of their potential application in future information technologies. [1][2][3][4][5][6] Rare-earth orthoferrites with weak ferromagnetism have become one of the most fascinating topics of research on antiferromagnets with ultrahigh resonant frequency. 7 Grown by the optical-floating-zone method or sintered by the solidstate reaction sintering method, 8,9 rare-earth orthoferrites have been demonstrated to have terahertz (THz)-driven spin excitation, ultrafast control magnetism with THz fields and spin reorientations.…”

Section: Introductionmentioning

confidence: 99%

Smoothing method to directly denoise terahertz signals in rare‐earth orthoferrite antiferromagnets

et al. 2021

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Rare-earth orthoferrites with weak ferromagnetism have become one of the most fascinating topics in antiferromagnet research because of their potential application in future information technologies. However, an appropriate and direct way to reduce the noise in the intrinsic but weak resonances of rare-earth orthoferrites is currently lacking, creating difficulties in analysis. Here, we report a numerical smoothing method to directly denoise the detected terahertz (THz) responses of orthoferrites using a B-spline algorithm. For comparison, the Savitzky-Golay smoothing method, which is a typical and widely used numerical smoothing method, was also used to process the data. The thickness-dependent signals of DyFeO 3 were processed by the above methods. LaFeO 3 , HoFeO 3 , and DyFeO 3 were chosen and prepared, and their thermally tunable signals were processed. The B-spline signal smoothing algorithm was shown to have stability and robustness to noise and was more effective than the Savitzky-Golay smoothing method at reducing noise. This work on smoothing thickness-and temperature-dependent THz signals may help provide a promising approach to reduce noise in the intrinsic but weak resonances of rare-earth orthoferrites.

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Disproportionation of Co²⁺ in the Topochemically Reduced Oxide LaSrCoRuO₅

Liang,

Batuk,

Orlandi

et al. 2024

Angewandte Chemie

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Complex transition‐metal oxides exhibit a wide variety of chemical and physical properties which are a strong function the local electronic states of the transition‐metal centres, as determined by a combination of metal oxidation state and local coordination environment. Topochemical reduction of the double perovskite oxide, LaSrCoRuO6, using Zr, yields LaSrCoRuO5. This reduced phase contains an ordered array of apex‐linked square‐based pyramidal Ru3+O5, square‐planar Co1+O4 and octahedral Co3+O6 units, consistent with the coordination‐geometry driven disproportionation of Co2+. Coordination‐geometry driven disproportionation of d7 transition‐metal cations (e.g. Rh2+, Pd3+, Pt3+) is common in complex oxides containing 4d and 5d metals. However, the weak ligand field experienced by a 3d transition‐metal such as cobalt leads to the expectation that d7+ Co2+ should be stable to disproportionation in oxide environments, so the presence of Co1+O4 and Co3+O6 units in LaSrCoRuO5 is surprising. Low‐temperature measurements indicate LaSrCoRuO5 adopts a ferromagnetically ordered state below 120 K due to couplings between S = 1/2 Ru3+ and S = 1 Co1+.

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Charge disproportionation and interchange transitions in twelve-layer BaFeO3

Cited by 12 publications

References 28 publications

Layered Hexagonal Perovskite Oxides 21R Ba₇Fe₅Ge₂O₂₀ and 12H Ba₆Fe₃Ge₃O₁₇

Layered Hexagonal Perovskite Oxides 21R Ba₇Fe₅Ge₂O₂₀ and 12H Ba₆Fe₃Ge₃O₁₇

Smoothing method to directly denoise terahertz signals in rare‐earth orthoferrite antiferromagnets

Disproportionation of Co²⁺ in the Topochemically Reduced Oxide LaSrCoRuO₅

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Charge disproportionation and interchange transitions in twelve-layer BaFeO3

Cited by 12 publications

References 28 publications

Layered Hexagonal Perovskite Oxides 21R Ba7Fe5Ge2O20 and 12H Ba6Fe3Ge3O17

Layered Hexagonal Perovskite Oxides 21R Ba7Fe5Ge2O20 and 12H Ba6Fe3Ge3O17

Smoothing method to directly denoise terahertz signals in rare‐earth orthoferrite antiferromagnets

Disproportionation of Co2+ in the Topochemically Reduced Oxide LaSrCoRuO5

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Product

Resources

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Layered Hexagonal Perovskite Oxides 21R Ba₇Fe₅Ge₂O₂₀ and 12H Ba₆Fe₃Ge₃O₁₇

Layered Hexagonal Perovskite Oxides 21R Ba₇Fe₅Ge₂O₂₀ and 12H Ba₆Fe₃Ge₃O₁₇

Disproportionation of Co²⁺ in the Topochemically Reduced Oxide LaSrCoRuO₅