Single-crystal elastic constants of Co-Al and Co-Fe spinels

Li, Z.; Fisher, E.S.; Liu, J. Z.; Nevitt, M. V.

doi:10.1007/bf02387728

Cited by 60 publications

(25 citation statements)

References 12 publications

(11 reference statements)

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“…42. It can be seen that, as already pointed out, the specific cation arrangement has nearly no influence on the value of ν 2D and thus C 11 and C 12 .…”

Section: B Epitaxial Strain and Elastic Propertiessupporting

confidence: 51%

Epitaxial strain effects in the spinel ferritesCoFe2O4andNiFe2O

2010

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The inverse spinels CoFe2O4 and NiFe2O4, which have been of particular interest over the past few years as building blocks of artificial multiferroic heterostructures and as possible spin-filter materials, are investigated by means of density functional theory calculations. We address the effect of epitaxial strain on the magneto-crystalline anisotropy and show that, in agreement with experimental observations, tensile strain favors perpendicular anisotropy, whereas compressive strain favors in-plane orientation of the magnetization. Our calculated magnetostriction constants λ100 of about −220 ppm for CoFe2O4 and −45 ppm for NiFe2O4 agree well with available experimental data. We analyze the effect of different cation arrangements used to represent the inverse spinel structure and show that both LSDA+U and GGA+U allow for a good quantitative description of these materials. Our results open the way for further computational investigations of spinel ferrites.

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“…42. It can be seen that, as already pointed out, the specific cation arrangement has nearly no influence on the value of ν 2D and thus C 11 and C 12 .…”

Section: B Epitaxial Strain and Elastic Propertiessupporting

confidence: 51%

Epitaxial strain effects in the spinel ferritesCoFe2O4andNiFe2O

2010

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“…was recorded recently for a crystal of nominal composition CoFe2O4 [9], but, the magnetostriction of a Co-rich crystal, Co1.1Fe1.9O4, was much less, (-375 ppm) [7], and the values can be quite variable. A result of the magnetostriction is that an imposed strain ε along <100> leads to a uniaxial anisotropy [10] Ku ≈ (3/2)100εE (2) where E is Young's modulus (C11), which is 257 GPa [11]. A 1% biaxial compression therefore leads to an easy-plane anisotropy Ku ≈ -2 MJm -3 .…”

Section: Introductionmentioning

confidence: 99%

“…where C12 = 106 GPa [11] The magnetic anisotropy of thin films of CoFe2O4 is exceptionally-sensitive to substrateinduced strain [10,[13][14][15][16][17][18].…”

Section: Introductionmentioning

confidence: 99%

Magnetization and anisotropy of cobalt ferrite thin films

Eskandari

Porter

Venkatesan

et al. 2017

Phys. Rev. Materials

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The magnetization of thin films of cobalt ferrite frequently falls far below the bulk value of 455 kAm -1 , which corresponds to an inverse cation distribution in the spinel structure with a significant orbital moment of about 0.6 µB that is associated with the octahedrally-coordinated Co 2+ ions. The orbital moment is responsible for the magnetostriction and magnetocrystalline anisotropy, and its sensitivity to imposed strain. We have systematically investigated the structure and magnetism of films produced by pulsed-laser deposition on different substrates (TiO2, MgO, MgAl2O4, SrTiO3, LSAT, LaAlO3) and as a function of temperature (500-700C) and oxygen pressure (10 -4 -10 Pa). Magnetization at room-temperature ranges from 60 to 440 kAm -1 , and uniaxial substrate-induced anisotropy ranges from +220 kJm -3 for films on deposited on MgO (100) to -2100 kJm -3 for films deposited on MgAl2O4 (100), where the roomtemperature anisotropy field reaches 14 T. No rearrangement of high-spin Fe 3+ and Co 2+ cations on tetrahedral and octahedral sites can reduce the magnetization below the bulk value, but a switch from Fe 3+ and Co 2+ to Fe 2+ and low-spin Co 3+ on octahedral sites will reduce the lowtemperature magnetization to 120 kAm -1 , and a consequent reduction of Curie temperature can bring the room-temperature value to near zero. Possible reasons for the appearance of low-spin cobalt in the thin films are discussed.

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“…The point defect reaction equation (12) de scribes the cation exchange in a phenomenological way. The corresponding microscopic processes may be quite complex.…”

Section: ^2mentioning

confidence: 99%

Some Aspects of Spinodal Decomposition in Spinel Solid Solutions

Burkert

Grüne

Schmalzried

et al. 1995

Zeitschrift Für Naturforschung A

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Dedicated to Professor Dr. E. Wicke on occasion of his 80th birthday Decomposition morphologies of supersaturated spinel solid solutions in the quasi-binary system Co2Ti04-CoAl20 4 at 973 K show all pertinent features of spinodal decomposition. Since the de composition morphology may not be considered as sufficient evidence for a spinodal process, the thermodynamics of the spinel solid solutions and the linear transport theory of spinodal decompo sition were combined to corroborate the experimental results of the early decomposition reaction.Simultaneous ordering, a common property of ternary and higher nonequilibrium solid solutions, was also observed. These ordering processes occur locally in distinct regions of the spinel crystal. Moreover, the spinodal wavelength X increases in time according to X cc t, which is unusual and will be discussed in the light of cation diffusion in semiconducting oxides with two cation sublattices.

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Single-crystal elastic constants of Co-Al and Co-Fe spinels

Cited by 60 publications

References 12 publications

Epitaxial strain effects in the spinel ferritesCoFe2O4andNiFe2O

Epitaxial strain effects in the spinel ferritesCoFe2O4andNiFe2O

Magnetization and anisotropy of cobalt ferrite thin films

Some Aspects of Spinodal Decomposition in Spinel Solid Solutions

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