An investigation of the magnetic anisotropy change in BaFe12−2xTixCoxO19 single crystals

Kreisel, J.; Vincent, H.; Tasset, F.; Paté, M.; Ganne, Jean‐Pierre

doi:10.1016/s0304-8853(00)01355-x

Cited by 123 publications

(76 citation statements)

References 33 publications

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“…It has been shown [2,7,21] that Ti has a strong preference for the 12k sites whilst Co 2+ prefers the 4f1 and the 2a sites, although there is significant contradiction in the literature [7,21,22]. The preference for Co 2+ in the tetrahedral (4f1) sites is reported to be due to the large Co 2+ cation radius (rCo(2+) = 0.58 Å) which stabilizes the S block compared to the smaller Fe 3+ cation (rFe(3+) = 0.49 Å) [21,23]. However, Fe 2+ , which has a larger ionic radius (rFe(2+) = 0.63 Å) than Co 2+ , may modify this picture and force the Co 2+ into the 2a or 12k sites.…”

Section: Discussionmentioning

confidence: 99%

Enhanced magnetoelectric effect in M-type hexaferrites by Co substitution into trigonal bi-pyramidal sites

Beevers

Love

Lazarov

et al. 2018

Applied Physics Letters

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Article:Beevers, J. E., Love, C. J., Lazarov, V. K. orcid.org/0000-0002-4314-6865 et al. The magnetoelectric effect in M-type Ti-Co doped strontium hexaferrite has been studied using a combination of magnetometry and element specific soft X-ray spectroscopies. A large increase (> x30) in the magnetoelectric coefficient is found when Co 2+ enters the trigonal bi-pyramidal site. The 5-fold trigonal bi-pyramidal site has been shown to provide an unusual mechanism for electric polarization based on the displacement of magnetic transition metal (TM) ions. For Co entering this site, an offcentre displacement of the cation may induce a large local electric dipole as well as providing an increased magnetostriction enhancing the magnetoelectric effect. INTRODUCTIONThe control of magnetism using applied electric fields offer the possibility of a new generation of ultralow power, high density storage. In this respect, magnetoelectric (ME) multiferroic materials are intensely studied in order to understand how different symmetry breaking orders exist in the same material and how these orders can be coupled. Among the few room temperature single-phase ME multiferroics reported, hexaferrites show potential for device applications as they exhibit a low field ME effect at room temperature [1]. M-type hexaferrites are arranged in different repeating sequences of basic building blocks; the R and S layers [2]. Fe 3+ cations occupy both octahedral (Oh) and tetrahedral (Td) co-ordinated sites in the S block (Wyckoff positions 2a and 4f1) and octahedral sites (12k and 4f2) in the R block, see online supplementary materials. The Ba ion located at positions 2d strongly distorts the octahedral site located at the 2b positions giving rise to a bi-pyramidal 5 fold co-ordination which induces a large uniaxial magnetic anisotropy parallel to the c-axis [3]. However, Co 2+ and Ti 4+ substitutions for Fe 3+ dramatically alters the magnetic properties [4]. Ti substitutions at the 12k sites decrease the exchange coupling between spins in the R and S blocks whilst Co substitutions change the magnetic anisotropy from uniaxial to an easy cone of magnetization tilted away from the c-axis. The result is to stabilize a non-collinear conical magnetic structure [2,5] which is of high interest in the field of multiferroics [6]. The ME effect at room temperature in SrFe8Ti2Co2O19 was first reported in bulk [7] and, thereafter, in thin films [8]. Co 2+ substitutions in ferrite structures are a well-known source of magnetoelastic coupling due to the large orbital moment of Co 2+ [9]. The linear ME coupling, , which is the change in magnetization with an applied electric field is directly proportional to the magnetoelastic coupling, or magnetostriction, , implying that an increase in  increases  [10]. However, a mechanism such as the piezoelectric effect or electrostriction for coupling the applied electric field into strain is also required. Several mechanisms for magnetically induced ferroelectricity have been proposed in recent years [11] with the sp...

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Section: Discussionmentioning

confidence: 99%

Enhanced magnetoelectric effect in M-type hexaferrites by Co substitution into trigonal bi-pyramidal sites

Beevers

Love

Lazarov

et al. 2018

Applied Physics Letters

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“…This M-type barium ferrite with a hexagonal molecular structure (BaFe 12 O 19 ) is an important permanent magnetic material with interesting magnetic properties [2,3] and thermal dynamics, such as large magnetocrystalline anisotropy [4], high Curie temperature, excellent chemical stability and corrosion resistivity [5].…”

Section: Introductionmentioning

confidence: 99%

Mössbauer Study of the Dynamics in BaFe₁₂O₁₉Single Crystals

Choi¹,

Sur²,

Lim³

et al. 2012

Journal of Magnetics

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Mössbauer spectra of hexagonal BaFe 12 O 19 single crystals were studied at various temperatures (4-300 K). It was found that the spin states in Fe atoms were parallel to the γ-ray's direction into a single crystal along the caxis. The location of the Fe ion in the 2b site is unusual in an oxide structure and has strong anisotropic lattice vibrations. Moreover, at room temperature, the zero absorption lines of the Fe ions at the 2b site were observed due to fast diffusion motion in a double well atomic potential. The two Fe ions of the single crystal mainly enter into the sites in the mirror plane of the trigonalbipyramidal structure.

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“…It is well known that their structural and magnetic properties are closely connected to the distribution of Fe ions among various interstitial sites, and it has been found that these properties can be changed by doping of Fe 3+ and Ba 2+ with different types of cations and cation combinations. Due to this, researchers have a lot of interest in modifying structural, magnetic and electrical properties of nanoferrites, according to the requirement for various practical applications by different cation substitutions and by using different synthetic routes under varying conditions [7][8][9][10][11]. Sandaranarayanan et al [7] studied the effect of annealing temperature on Barium ferrites and reported that their crystallization begins around 550℃ and fully crystalline phase is obtained in the range of 700℃ -900℃.…”

Section: Introductionmentioning

confidence: 99%

“…The saturation magnetization has also been reported to decrease with increase in Zn-Sn concentration. Kresisel et al [9] reported that with increasing concentration of Co-Ti dopants in barium ferrites, axial anisotropy reduced and further changed to nearly planar magnetic anisotropy. Teh et al [10] synthesized Co 2+ and Co 3+ substituted Ba ferrites via sol-gel method and found that Co 2+ doping decreases the value of coercivity and saturation magnetisation significantly.…”

Section: Introductionmentioning

confidence: 99%

Structural and Magnetic Properties of BaCoxFe12xO19 (x = 0.2, 0.4, 0.6, &1.0) Nanoferrites Synthesized via Citrate Sol-Gel Method

Singhal¹,

Kaur²,

Jauhar³

et al. 2011

WJCMP

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An investigation of the magnetic anisotropy change in BaFe12−2xTixCoxO19 single crystals

Cited by 123 publications

References 33 publications

Enhanced magnetoelectric effect in M-type hexaferrites by Co substitution into trigonal bi-pyramidal sites

Enhanced magnetoelectric effect in M-type hexaferrites by Co substitution into trigonal bi-pyramidal sites

Mössbauer Study of the Dynamics in BaFe₁₂O₁₉Single Crystals

Structural and Magnetic Properties of BaCo<sub>x</sub>Fe<sub>12x</sub>O<sub>19</sub> (x = 0.2, 0.4, 0.6, &1.0) Nanoferrites Synthesized via Citrate Sol-Gel Method

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An investigation of the magnetic anisotropy change in BaFe12−2xTixCoxO19 single crystals

Cited by 123 publications

References 33 publications

Enhanced magnetoelectric effect in M-type hexaferrites by Co substitution into trigonal bi-pyramidal sites

Enhanced magnetoelectric effect in M-type hexaferrites by Co substitution into trigonal bi-pyramidal sites

Mössbauer Study of the Dynamics in BaFe12O19Single Crystals

Structural and Magnetic Properties of BaCo&lt;sub&gt;x&lt;/sub&gt;Fe&lt;sub&gt;12x&lt;/sub&gt;O&lt;sub&gt;19&lt;/sub&gt; (x = 0.2, 0.4, 0.6, &amp;1.0) Nanoferrites Synthesized via Citrate Sol-Gel Method

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Mössbauer Study of the Dynamics in BaFe₁₂O₁₉Single Crystals

Structural and Magnetic Properties of BaCo<sub>x</sub>Fe<sub>12x</sub>O<sub>19</sub> (x = 0.2, 0.4, 0.6, &1.0) Nanoferrites Synthesized via Citrate Sol-Gel Method