The High Magnetic Field Facility of the University of Amsterdam

Boer, F.R. de; Wolfrat, Jules; Muller, F.; Roeland, L.W.

doi:10.1016/b978-0-444-86566-3.50048-2

Cited by 44 publications

(22 citation statements)

References 9 publications

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“…16 The measurements were performed on free powders which were sieved in a 40 m sieve to assure that the particles are single crystalline. The magnetization was measured both in quasi-stationary fields ͑constant during 0.1 s͒ as well as in fields increasing and decreasing linearly with time.…”

Section: Methodsmentioning

confidence: 99%

Magnetic properties ofR6Fe13−xM1+x
Groot
¹
,
Buschow
²
,
Boer
³

1998
Phys. Rev. B
51
5
20
0
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The magnetic properties of various R 6 Fe 13Ϫx M 1ϩx compounds (RϭLa, Nd, Gd, and Dy͒ crystallizing in the La 6 Co 11 Ga 3 structure have been investigated by magnetic measurements and x-ray diffraction. It is shown that all Nd 6 Fe 13 M compounds with M ϭAu, Ag, Cu, Si, and Ga order antiferromagnetically around 415 K and evidence is provided that the frequently reported, increase of the magnetization at lower temperature is due to impurities. High-field measurements made at 4.2 K on Nd 6Ϫx Dy x Fe 12.7 Ga 1.3 compounds with xϭ0.0, 0.2, 0.5, and 1.0 show that the R-Fe coupling is not yet broken at 35 T. A large hysteresis in the field dependence of the magnetization is present in all compounds including La 6 Fe 11 Al 3 , indicating the role of the Fe-sublattice anisotropy. A theoretical model for the field dependence of the magnetization is constructed, based on local minimization of the free energy. By taking into account the second-and fourth-order magnetocrystalline anisotropy terms, the magnetization behavior of the compounds, including the large hysteresis, can be explained excellently. A structure of ferromagnetically ordered Fe sheets coupling antiferromagnetically to each other is proposed to explain the experimental data. The hydrides of these compounds are all ferromagnetic ͑light R) or ferrimagnetic ͑heavy R) and have an easy magnetization direction along the c axis due to the Fe-sublattice anisotropy. Their ordering temperatures are near 450 K, just slightly above the Néel temperature of the parent compounds, which can be understood from the proposed spin structure.

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Section: Methodsmentioning

confidence: 99%

Magnetic properties ofR6Fe13−xM1+x
Groot
¹
,
Buschow
²
,
Boer
³

1998
Phys. Rev. B
51
5
20
0
View full text Add to dashboard Cite

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“…Reference 35 expresses this correction as a negative term that has to be added to the net measured strain. The form factor strains for thin disks of a material with cubic symmetry given by Gersdorf 2 are,…”

Section: Appendix B: Form Effectmentioning

confidence: 99%

Tetragonal magnetostriction and magnetoelastic coupling in Fe-Al, Fe-Ga, Fe-Ge, Fe-Si, Fe-Ga-Al, and Fe-Ga-Ge alloys

Restorff

Wun‐Fogle

Hathaway

et al. 2012

Journal of Applied Physics

116

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This paper presents a comparative study on the tetragonal magnetostriction constant,λ γ,2 , [ = (3/2)λ 100 ] and magnetoelastic coupling, b 1 , of binary Fe 100-xZ x (0 < x < 35, Z = Al, Ga, Ge, and Si) and ternary Fe-Ga-Al and Fe-Ga-Ge alloys. The quantities are corrected for magnetostrains due to sample geometry (the magnetostrictive form effect). Recently published elastic constant data along with magnetization measurements at both room temperature and 77 K make these corrections possible. The form effect correction lowers the magnetostriction by ∼10 ppm for high-modulus alloys and by as much as 30 ppm for low-modulus alloys. The elastic constants are also used to determine the values of the magnetoelastic coupling constant, b 1 . With the new magnetostriction data on the Fe-Al-Ga alloy, it is possible to show how the double peak magnetostriction feature of the binary Fe-Ga alloy flows into the single peak binary Fe-Al alloy. The corrected magnetostriction and magnetoelastic coupling data for the various alloys are also compared using the electron-per-atom ratio, e/a, as the common variable. The Hume-Rothery rules link thee/a ratio to the regions of phase stability, which appear to be intimately related to the magnetostriction versus the solute concentration curve in these alloys. Using e/a as the abscissa tends to align the peaks in the magnetostriction and magnetoelastic coupling for the Fe-Ga, Fe-Ge, Fe-Al, Fe-Ga-Al, and Fe-Ga-Ge alloys, but not for the Fe-Si alloys for which the larger atomic size difference may play a greater role in phase stabilization. Corrections for the form effect are also presented for the rhombohedral magnetostriction,λ ɛ,2 , and the magnetoelastic coupling, b 2 , of Fe 100-x Ga x (0 < x < 35) alloys.Keywords aluminium alloys, elastic constants, elastic moduli, gallium alloys, germanium alloys, iron alloys, magnetisation, magnetoelastic effects, magnetostriction, silicon alloys Disciplines Condensed Matter Physics | Metallurgy CommentsThe following article is from Journal of Applied Physics 111 (2012) This paper presents a comparative study on the tetragonal magnetostriction constant, k c,2 , [ ¼ (3/2) k 100 ] and magnetoelastic coupling, b 1 , of binary Fe 100-x Z x (0 < x < 35, Z ¼ Al, Ga, Ge, and Si) and ternary Fe-Ga-Al and Fe-Ga-Ge alloys. The quantities are corrected for magnetostrains due to sample geometry (the magnetostrictive form effect). Recently published elastic constant data along with magnetization measurements at both room temperature and 77 K make these corrections possible. The form effect correction lowers the magnetostriction by $10 ppm for high-modulus alloys and by as much as 30 ppm for low-modulus alloys. The elastic constants are also used to determine the values of the magnetoelastic coupling constant, b 1 . With the new magnetostriction data on the Fe-Al-Ga alloy, it is possible to show how the double peak magnetostriction feature of the binary Fe-Ga alloy flows into the single peak binary Fe-Al alloy. The corrected magnetostriction and magnetoel...

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“…To determine k 111 , the {110} oriented disks were bonded with a strain gauge aligned along a h111i in-plane direction. The magnetostriction measurements were corrected for the form effect employing Gersdorf's method, 12 using the fitted elastic constants from above and an estimate of saturation magnetization taken from Ref. 13, p. 714, for pure Fe.…”

Section: -mentioning

confidence: 99%

Rhombohedral magnetostriction in dilute iron (Co) alloys

Jones

Petculescu

Wun‐Fogle

et al. 2015

Journal of Applied Physics

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Iron is a well-utilized material in structural and magnetic applications. This does not mean, however, that it is well understood, especially in the field of magnetostriction. In particular, the rhombohedral magnetostriction of iron, λ111 , is anomalous in two respects: it is negative in sign, in disagreement with the prediction of first principles theory, and its magnitude decreases with increasing temperature much too rapidly to be explained by a power law dependence on magnetization. These behaviors could arise from the location of the Fermi level, which leaves a small region of the majority 3d t2g states unfilled, possibly favoring small internal displacements that split these states. If this view is correct, adding small amounts of Co to Fe fills some of these states, and the value of λ111 should increase toward a positive value, as predicted for perfect bcc Fe. We have measured the magnetostriction coefficients (λ111 and λ100) of pure Fe, Fe97Co3, and Fe94Co6 single crystals from 77 K to 450 K. Resonant ultrasound spectroscopy has been used to check for anomalies in the associated elastic constants, c 44 and c′. The additional electrons provided by the cobalt atoms indeed produced positive contributions to bothmagnetostriction constants, λ111 and λ100, exhibiting an increase of 2.8 × 10 −6 per at. % Co for λ111 and 3.8 × 10 −6 per at. % Co for λ100. Iron is a well-utilized material in structural and magnetic applications. This does not mean, however, that it is well understood, especially in the field of magnetostriction. In particular, the rhombohedral magnetostriction of iron, k 111 , is anomalous in two respects: it is negative in sign, in disagreement with the prediction of first principles theory, and its magnitude decreases with increasing temperature much too rapidly to be explained by a power law dependence on magnetization. These behaviors could arise from the location of the Fermi level, which leaves a small region of the majority 3d t 2g states unfilled, possibly favoring small internal displacements that split these states. If this view is correct, adding small amounts of Co to Fe fills some of these states, and the value of k 111 should increase toward a positive value, as predicted for perfect bcc Fe. We have measured the magnetostriction coefficients (k 111 and k 100 ) of pure Fe, Fe 97 Co 3 , and Fe 94 Co 6 single crystals from 77 K to 450 K. Resonant ultrasound spectroscopy has been used to check for anomalies in the associated elastic constants, c 44 and c 0 . The additional electrons provided by the cobalt atoms indeed produced positive contributions to both magnetostriction constants, k 111 and k 100 , exhibiting an increase of 2.8 Â 10 À6 per at. % Co for k 111 and 3.8 Â 10 À6 per at. % Co for k 100 . V C 2015 AIP Publishing LLC. [http://dx

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The High Magnetic Field Facility of the University of Amsterdam

Cited by 44 publications

References 9 publications

Magnetic properties ofR6Fe13−xM1+x
Groot
¹
,
Buschow
²
,
Boer
³

1998
Phys. Rev. B
51
5
20
0
View full text Add to dashboard Cite

Magnetic properties ofR6Fe13−xM1+x
Groot
¹
,
Buschow
²
,
Boer
³

1998
Phys. Rev. B
51
5
20
0
View full text Add to dashboard Cite

Tetragonal magnetostriction and magnetoelastic coupling in Fe-Al, Fe-Ga, Fe-Ge, Fe-Si, Fe-Ga-Al, and Fe-Ga-Ge alloys

Rhombohedral magnetostriction in dilute iron (Co) alloys

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The High Magnetic Field Facility of the University of Amsterdam

Cited by 44 publications

References 9 publications

Magnetic properties ofR6Fe13−xM1+xGroot1, Buschow2, Boer3 1998Phys. Rev. B515200View full textAdd to dashboardCite

Magnetic properties ofR6Fe13−xM1+xGroot1, Buschow2, Boer3 1998Phys. Rev. B515200View full textAdd to dashboardCite

Tetragonal magnetostriction and magnetoelastic coupling in Fe-Al, Fe-Ga, Fe-Ge, Fe-Si, Fe-Ga-Al, and Fe-Ga-Ge alloys

Rhombohedral magnetostriction in dilute iron (Co) alloys

Contact Info

Product

Resources

About

Magnetic properties ofR6Fe13−xM1+x
Groot
¹
,
Buschow
²
,
Boer
³

1998
Phys. Rev. B
51
5
20
0
View full text Add to dashboard Cite

Magnetic properties ofR6Fe13−xM1+x
Groot
¹
,
Buschow
²
,
Boer
³

1998
Phys. Rev. B
51
5
20
0
View full text Add to dashboard Cite