An X-ray study of non-zero nickel moment in a ferromagnetic shape-memory alloy

Islam, Zahirul; Haskel, D.; Lang, J. C.; Srajer, G.; Lee, Y.; Harmon, B. N.; Goldman, A. I.; Schlagel, Deborah L.; Lograsso, Thomas A.

doi:10.1016/j.jmmm.2005.10.245

Cited by 19 publications

(5 citation statements)

References 34 publications

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“…Particularly, at low temperature (14 K), the distribution component has δ = 0.24 mm s −1 and a B hf peak value of 16 (1) T, which roughly agree with the hyperfine parameters observed for the 57 FeMn-7 sample, suggesting that part of the substituting Fe atoms prefers to be in the Mn instead of the Ni sites. Conversely, the fraction of 57 Fe atoms (40% of the spectra) that occupies at the Ni sites can be related to the broad singlet with an average δ of 0.18(8) mm s −1 at 14 K. Furthermore, the noted broadening observed in the singlet absorption line when the temperature is reduced can be associated with a magnetic ordering of this component, which allows us to estimate magnetic moments smaller than 0.1µ B /Fe in Ni sites in accordance with the results reported in the literature for Ni magnetic moments in the L2 1 -type structure [8,11,17].…”

Section: Sextetsupporting

confidence: 89%

“…Ni 2 MnZ Heusler alloys (Z = Sn, In, Ga) have attracted special attention in the last five years due to their rich magnetic phase diagrams and their potential for technological applications, which are mainly associated with their observed martensitic phase transformations (MPTs) [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17]. In these alloys, the magnetic properties are practically governed by the Mn magnetic moments, since Ni atoms are assumed to have a small or negligible moment [8,11,16,17]. On the other hand, in Mn rich NiMnSn-based Heusler alloys the MPT can be related to the presence of short-range antiferromagnetic (AFM) ordering between Mn atoms in the martensitic phase [2,5,7].…”

Section: Introductionmentioning

confidence: 99%

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Magnetic studies of Fe-doped martensitic Ni₂Mn_1.44Sn_0.56-type Heusler alloy

Passamani¹,

Córdova²,

Alves³

et al. 2009

J. Phys. D: Appl. Phys.

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Localization and magnetism of Fe replacing either Mn or Ni in the Ni2Mn1.44Sn0.56-type Heusler alloy have been systematically investigated using magnetization, scanning electron microscopy and Mössbauer spectroscopy. It has been shown that the addition of Fe either in Mn or in Ni sites reduces the fraction of the Mn-rich NiMnSn-type Heusler alloys that has short-range antiferromagnetic interactions; consequently it reduces the martensitic–austenitic transition temperature and increases the thermal hysteresis width due to an increase in atomic disorder caused by Fe replacements. The Fe atoms in Mn sites have two magnetic configurations with magnetic moments of 0.8μB/Fe and 1.4μB/Fe in the martensitic orthorhombic structure, while Fe in Ni sites have magnetic moments smaller than 0.1μB/Fe. These results indicate that the Fe atoms are distinctly substituting either Mn or Ni and the decrease in the martensitic phase transition temperature for increasing Fe content can be mainly attributed to the Fe atoms in the Mn sites in both cases.

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Section: Sextetsupporting

confidence: 89%

Section: Introductionmentioning

confidence: 99%

Magnetic studies of Fe-doped martensitic Ni₂Mn_1.44Sn_0.56-type Heusler alloy

Passamani¹,

Córdova²,

Alves³

et al. 2009

J. Phys. D: Appl. Phys.

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“…As discussed above, no clear relationship between the XMCD at the Mn K-edge and the main 3d magnetic moment can be given. Despite this fact, Islam et al [26] conclude from the occurrence of XMCD at the Ni K-edge in the related ferromagnetic shape-memory NiMnGa alloys that Ni carries a significant 3d moment. However, the existence of non-zero XMCD at the Ni K-edge does not constitute itself as evidence of a 3d moment.…”

Section: Resultsmentioning

confidence: 99%

XAS and XMCD study of the influence of annealing on the atomic ordering and magnetism in an NiMnGa alloy

Chaboy

Lázpita

Barandiarán

et al. 2008

J. Phys.: Condens. Matter

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The proper annealing of Ni(51)Mn(28)Ga(21) ribbon alloy gives rise to an increase of the saturation magnetization and of the magnetic order T(C) (up to 20 K) and martensitic transition T(M) (up to 10 K) temperatures. The combined x-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) studies indicate that the annealing treatment drives the alloy to a more ordered structure without significantly affecting the local structure in terms of interatomic distances and bonding geometry. By contrast, the annealing strongly affects the near-edge absorption at the Mn K-edge while no effect is observed at either the Ni or Ga K-edge. These results suggest that annealing leads to a modification of the electronic structure of the Mn atoms while that of Ni and Ga atoms remains unvaried. However, strong XMCD signals are detected at both Ni and Ga K-edges whose amplitude increases after annealing. These results point out that despite the change of the magnetic properties of the system being mainly associated with the modification of the electronic properties of the Mn atoms, both Ni and Ga may play a non-negligible role through the polarization of the conduction band.

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“…The MT temperature (T m ) strongly depends on composition [9] and the compositional dependence has been traditionally described as a function of the electron to atom ratio, e/a, just as it occurs in the Hume-Rothery compounds [10]. It is also well known that the ferromagnetism in these alloys is due to the ferromagnetic coupling between the Mn atoms, in which the magnetic moment of the alloy is mainly located, and, to a lesser extent, due to the Ni-Mn coupling [11,12].…”

Section: Introductionmentioning

confidence: 99%

Effect of atomic order on the martensitic and magnetic transformations in Ni–Mn–Ga ferromagnetic shape memory alloys

Sánchez-Alarcos¹,

Pérez-Landazábal²,

Recarte³

et al. 2010

J. Phys.: Condens. Matter

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The influence of long-range L2(1) atomic order on the martensitic and magnetic transformations of Ni-Mn-Ga shape memory alloys has been investigated. In order to correlate the structural and magnetic transformation temperatures with the atomic order, calorimetric, magnetic and neutron diffraction measurements have been performed on polycrystalline and single-crystalline alloys subjected to different thermal treatments. It is found that both transformation temperatures increase with increasing atomic order, showing exactly the same linear dependence on the degree of L2(1) atomic order. A quantitative correlation between atomic order and transformation temperatures has been established, from which the effect of atomic order on the relative stability between the structural phases has been quantified. On the other hand, the kinetics of the post-quench ordering process taking place in these alloys has been studied. It is shown that the activation energy of the ordering process agrees quite well with the activation energy of the Mn self-diffusion process.

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An X-ray study of non-zero nickel moment in a ferromagnetic shape-memory alloy

Cited by 19 publications

References 34 publications

Magnetic studies of Fe-doped martensitic Ni₂Mn_1.44Sn_0.56-type Heusler alloy

Magnetic studies of Fe-doped martensitic Ni₂Mn_1.44Sn_0.56-type Heusler alloy

XAS and XMCD study of the influence of annealing on the atomic ordering and magnetism in an NiMnGa alloy

Effect of atomic order on the martensitic and magnetic transformations in Ni–Mn–Ga ferromagnetic shape memory alloys

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An X-ray study of non-zero nickel moment in a ferromagnetic shape-memory alloy

Cited by 19 publications

References 34 publications

Magnetic studies of Fe-doped martensitic Ni2Mn1.44Sn0.56-type Heusler alloy

Magnetic studies of Fe-doped martensitic Ni2Mn1.44Sn0.56-type Heusler alloy

XAS and XMCD study of the influence of annealing on the atomic ordering and magnetism in an NiMnGa alloy

Effect of atomic order on the martensitic and magnetic transformations in Ni–Mn–Ga ferromagnetic shape memory alloys

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Magnetic studies of Fe-doped martensitic Ni₂Mn_1.44Sn_0.56-type Heusler alloy

Magnetic studies of Fe-doped martensitic Ni₂Mn_1.44Sn_0.56-type Heusler alloy