Mössbauer study of the new pyrochlore form of FeF3

Calagé, Y.; Zemirli, M.; Grenèche, Jean‐Marc; Varret, F.; Pape, R. De; Férey, Gérard

doi:10.1016/0022-4596(87)90074-0

Cited by 24 publications

(13 citation statements)

References 9 publications

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“…A number of non-oxide pyrochlores are known [27,32] including chlorides [33] and fluorides. [34,35] The pyrochlore structure is therefore highly "tailorable"; e.g., the identities and oxidation states of the B-cations, which play a leading role in electronic properties, can be controlled by achieving electroneutrality through deliberate choices of the A and OЈ ions and their concentrations.…”

Section: Introductionmentioning

confidence: 99%

An Unexpected Crystal‐Chemical Principle for the Pyrochlore Structure

2005

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Phase equilibrium studies of the Bi-Zn-Nb-O system show that pyrochlore does not form at chemical compositions predicted by the traditional formula for this crystal structure, A 2 B 2 O 6 OЈ, where A denotes large (8-coordinated, e.g. Bi 3+ ) and B small (6-coordinated, e.g. Zn 2+, Nb 5+ ) cation sites. Instead, pyrochlore forms only at compositions with excess B cations which, surprisingly, occupy the large A-cation sites. Reports of similar behavior in other pyrochlores suggest a

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Section: Introductionmentioning

confidence: 99%

An Unexpected Crystal‐Chemical Principle for the Pyrochlore Structure

2005

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“…Heisenberg exchange. Neutron scattering and Mössbauer experiments find long-range magnetic order below T c ≈ 20 +2 −5 K [2, [16][17][18][19]]. Yet, the static magnetic susceptibility shows a deviation from the Curie-Weiss law even at 300 K, implying the existence of strong antiferromagnetic exchange and short-range correlations extending up to temperatures much higher than T c [2] and thus a very high degree of frustration [2,20].…”

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Spin Hamiltonian, order out of a Coulomb phase, and pseudocriticality in the frustrated pyrochlore Heisenberg antiferromagnetFeF3

et al. 2015

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FeF3, with its half-filled Fe 3+ 3d orbital, hence zero orbital angular momentum and S = 5/2, is often put forward as a prototypical highly-frustrated classical Heisenberg pyrochlore antiferromagnet. By employing ab initio density functional theory (DFT), we obtain an effective spin Hamiltonian for this material. This Hamiltonian contains nearest-neighbor antiferromagnetic Heisenberg, bi-quadratic and Dzyaloshinskii-Moriya interactions as dominant terms and we use Monte Carlo simulations to investigate the nonzero temperature properties of this minimal model. We find that upon decreasing temperature, the system passes through a Coulomb phase, composed of shortrange correlated coplanar states, before transforming into an "all-in/all-out" (AIAO) state via a very weakly first order transition at a critical temperature Tc ≈ 22 K, in good agreement with the experimental value for a reasonable set of Coulomb interaction U and Hund's coupling JH describing the material. Despite the transition being first order, the AIAO order parameter evolves below Tc with a power-law behavior characterized by a pseudo "critical exponent" β ≈ 0.18 in accord with experiment. We comment on the origin of this unusual β value.

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“…The extensive compositional ranges known for pyrochlore compounds reflect the versatility of the A 2 O substructure: "defect" pyrochlores form readily since this network can be partially occupied or even completely absent, as in the pyrochlore-type polymorph of WO 3 and oxysulfide pyrochlores. A number of non-oxide pyrochlores are known [29] including chlorides [30] and fluorides [31,32]. The pyrochlore structure is therefore highly "tailorable"; e.g., the identities and oxidation states of the B cations, which play a leading role in electronic properties, can be controlled by achieving electroneutrality through deliberate choices of the A and O ions and their concentrations.…”

Section: Introductionmentioning

confidence: 99%