Anharmonic phonons and magnons in BiFeO 3

O. Delaire; M. B. Stone; J. Ma; A. Huq; D. Gout; C. Brown; K. F. Wang; Z. F. Ren

doi:10.1103/PhysRevB.85.064405

Anharmonic phonons and magnons in BiFeO ₃

O. Delaire, M. B. Stone, J. Ma, A. Huq, D. Gout, C. Brown, K. F. Wang, Z. F. Ren

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Abstract

The phonon density of states (DOS) and magnetic excitation spectrum of polycrystalline BiFeO ₃ were measured for temperatures 200≤T≤750K, using inelastic neutron scattering (INS). Our results indicate that the magnetic spectrum of BiFeO ₃ closely resembles that of similar Fe perovskites, such as LaFeO ₃, despite the cycloid modulation in BiFeO ₃. We do not find any evidence for a spin gap. A strong T dependence of the phonon DOS was found, with a marked broadening of the whole spectrum, providing evidence of strong anharmonicity. This anharmonicity is corroborated by large-amplitude motions of Bi and O ions observed with neutron diffraction. A clear anomaly is seen in the T dependence of Bi-dominated modes across the Néel transition. These results highlight the importance of spin-phonon coupling in this material.

Original language	English
Article number	064405
Journal	Physical Review B - Condensed Matter and Materials Physics
Volume	85
Issue number	6
DOIs	https://doi.org/10.1103/PhysRevB.85.064405
State	Published - Feb 13 2012

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abstract = "The phonon density of states (DOS) and magnetic excitation spectrum of polycrystalline BiFeO 3 were measured for temperatures 200≤T≤750K, using inelastic neutron scattering (INS). Our results indicate that the magnetic spectrum of BiFeO 3 closely resembles that of similar Fe perovskites, such as LaFeO 3, despite the cycloid modulation in BiFeO 3. We do not find any evidence for a spin gap. A strong T dependence of the phonon DOS was found, with a marked broadening of the whole spectrum, providing evidence of strong anharmonicity. This anharmonicity is corroborated by large-amplitude motions of Bi and O ions observed with neutron diffraction. A clear anomaly is seen in the T dependence of Bi-dominated modes across the N{\'e}el transition. These results highlight the importance of spin-phonon coupling in this material.",

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T1 - Anharmonic phonons and magnons in BiFeO 3

AU - Delaire, O.

AU - Stone, M. B.

AU - Ma, J.

AU - Huq, A.

AU - Gout, D.

AU - Brown, C.

AU - Wang, K. F.

AU - Ren, Z. F.

PY - 2012/2/13

Y1 - 2012/2/13

N2 - The phonon density of states (DOS) and magnetic excitation spectrum of polycrystalline BiFeO 3 were measured for temperatures 200≤T≤750K, using inelastic neutron scattering (INS). Our results indicate that the magnetic spectrum of BiFeO 3 closely resembles that of similar Fe perovskites, such as LaFeO 3, despite the cycloid modulation in BiFeO 3. We do not find any evidence for a spin gap. A strong T dependence of the phonon DOS was found, with a marked broadening of the whole spectrum, providing evidence of strong anharmonicity. This anharmonicity is corroborated by large-amplitude motions of Bi and O ions observed with neutron diffraction. A clear anomaly is seen in the T dependence of Bi-dominated modes across the Néel transition. These results highlight the importance of spin-phonon coupling in this material.

AB - The phonon density of states (DOS) and magnetic excitation spectrum of polycrystalline BiFeO 3 were measured for temperatures 200≤T≤750K, using inelastic neutron scattering (INS). Our results indicate that the magnetic spectrum of BiFeO 3 closely resembles that of similar Fe perovskites, such as LaFeO 3, despite the cycloid modulation in BiFeO 3. We do not find any evidence for a spin gap. A strong T dependence of the phonon DOS was found, with a marked broadening of the whole spectrum, providing evidence of strong anharmonicity. This anharmonicity is corroborated by large-amplitude motions of Bi and O ions observed with neutron diffraction. A clear anomaly is seen in the T dependence of Bi-dominated modes across the Néel transition. These results highlight the importance of spin-phonon coupling in this material.

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Anharmonic phonons and magnons in BiFeO ₃

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