Forced magnetostriction of ferromagnetic Heusler alloy Ni<sub>2</sub>MnGa at the Curie temperature

Sakon, Takuo; Hayashi, Yuhi; Fujimoto, Naoki; Kanomata, T.; Nojiri, Hiroyuki; Adachi, Yasuhiro

doi:10.1063/1.5036558

Cited by 10 publications

(19 citation statements)

References 13 publications

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“…The reaction products were encapsulated in evacuated silica tubes and heated at 1073 K for 3 days and 773 K for 2 more days, then quenched in water. A detailed explanation of the experimental procedure has been given in a previous studies [16,27].…”

Section: Methodsmentioning

confidence: 99%

“…Some researchers have investigated the magnetism of Ni 2 MnGa-type Heusler alloys by means of spin fluctuation theories [11,12,13,14,15,16,17,18]. Spin fluctuation theories for the itinerant electron magnetism have been used to evaluate the physics of the itinerant electron system [11,12,19,20,21,22].…”

Section: Introductionmentioning

confidence: 99%

“…In a previous study, we investigated the magnetization and the magnetostriction of Ni 2+ x MnGa 1 − x ( x = 0.00, 0.02, and 0.04) to determine whether these relations were preserved when the valence electron concentration per atom, e / a, changed [16,17,18]. When the value of x for Ni 2+ x MnGa 1 − x increased, e / a increased.…”

Section: Introductionmentioning

confidence: 99%

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The Characteristic Properties of Magnetostriction and Magneto-Volume Effects of Ni2MnGa-Type Ferromagnetic Heusler Alloys

et al. 2019

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In this article, we review the magnetostriction and magneto-volume effects of Ni2MnGa-type ferromagnetic Heusler alloys at the martensitic, premartensitic, and austenitic phases. The correlations of forced magnetostriction (ΔV/V) and magnetization (M), using the self-consistent renormalization (SCR) spin fluctuation theory of an itinerant electron ferromagnet proposed by Takahashi, are evaluated for the ferromagnetic Heusler alloys. The magneto-volume effect occurs due to the interaction between the magnetism and volume change of the magnetic crystals. The magnetic field-induced strain (referred to as forced magnetostriction) and the magnetization are measured, and the correlation of magnetostriction and magnetization is evaluated. The forced volume magnetostriction ΔV/V at the Curie temperature, TC is proportional to M4, and the plots cross the origin point; that is, (M4, ΔV/V) = (0, 0). This consequence is in good agreement with the spin fluctuation theory of Takahashi. An experimental study is carried out and the results of the measurement agree with the theory. The value of forced magnetostriction is proportional to the valence electron concentration per atom (e/a). Therefore, the forced magnetostriction reflects the electronic states of the ferromagnetic alloys. The magnetostriction near the premartensitic transition temperature (TP) induces lattice softening; however, lattice softening is negligible at TC. The forced magnetostriction at TC occurs due to spin fluctuations of the itinerant electrons. In the martensitic and premartensitic phases, softening of the lattice occurs due to the shallow hollow (potential barrier) of the total energy difference between the L21 cubic and modulated 10M or 14M structures. As a result, magnetostriction is increased by the magnetic field.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The Characteristic Properties of Magnetostriction and Magneto-Volume Effects of Ni2MnGa-Type Ferromagnetic Heusler Alloys

et al. 2019

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“…The theory proposed by Takahashi indicates that the magnetic field dependence, H , is proportional to the magnetization, M 5 , at the Curie temperature, T C . This property was obtained by the differential calculus of the magnetization of the spin fluctuation free energy [7,8,9].…”

Section: Introductionmentioning

confidence: 99%

“…MnSi [10], Fe x Co 1− x Si [11], CoS 2 [12], and Ni [13] followed the relationship provided in Equation (1). The Heusler isotropic ferromagnetic alloy Ni 2+ x MnGa 1− x ( x = 0.00, 0.02, 0.04) also followed the relationship mentioned in Equation (1) [8,9,13]. From the spontaneous magnetic moment and magnetization at T C , we obtained the spin fluctuation parameter in k -space (momentum space, T A ) and in energy space ( T 0 ).…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Itinerant Electron Ferromagnetism of Ni2+xMnGa1−x and Co2VGa Heusler Alloys

et al. 2019

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Experimental investigations into the field dependence of magnetization and temperature dependences of magnetic susceptibility in Ni2+xMnGa1−x (x = 0.00, 0.02, 0.04) and Co2VGa Heusler alloy ferromagnets were performed following the spin fluctuation theory of itinerant ferromagnetism, called as “Takahashi theory”. We investigated the magnetic field dependence of magnetization at the Curie temperature TC, which is the critical temperature of the ferromagnetic–paramagnetic transition, and also at T = 5 K, which concerns the ground state of the ferromagnetic state. The field dependence of the magnetization was analyzed by means of the H vs. M5 dependence, and the field dependence of the ground state at 5 K was investigated by means of an Arrott plot (H/M vs. M2) according to the Takahashi theory. As for Ni2+xMnGa1−x, the spin fluctuation parameter in k-space (momentum space, TA) and that in energy space (T0) obtained at TC and 5 K were almost the same. On the contrary, as for Co2VGa, the H vs. M5 dependence was not shown at TC. We obtained TA and T0 by means of an Arrott plot at 5 K. We created a generalized Rhodes–Wohlfarth plot of peff/pS versus TC/T0 for the other ferromagnets. The plot indicated that the relationship between peff/pS and T0/TC followed Takahashi’s theory. We also discussed the spontaneous magnetic moment at the ground state, pS, which was obtained by an Arrott plot at 5 K and the high temperature magnetic moment, pC, at the paramagnetic phase. As for the localized ferromagnet, the pC/pS was 1. As for weak ferromagnets, the pC/pS was larger than 1. In contrast, the pC/pS was smaller than 1 by many Heusler alloys. This is a unique property of Heusler ferromagnets. Half-metallic ferromagnets of Co2VGa and Co2MnGa were in accordance with the generalized Rhodes–Wohlfarth plot with a km around 1.4. The magnetic properties of the itinerant electron of these two alloys appeared in the majority bands and was confirmed by Takahashi’s theory.

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Origin of heterogeneous magnetostriction: A case study of nanoprecipitates-bearing Fe-Mo alloys

Zhang

Yang

Gou

et al. 2022

Journal of Alloys and Compounds

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Forced magnetostriction of ferromagnetic Heusler alloy Ni₂MnGa at the Curie temperature

Cited by 10 publications

References 13 publications

The Characteristic Properties of Magnetostriction and Magneto-Volume Effects of Ni2MnGa-Type Ferromagnetic Heusler Alloys

The Characteristic Properties of Magnetostriction and Magneto-Volume Effects of Ni2MnGa-Type Ferromagnetic Heusler Alloys

Investigation of the Itinerant Electron Ferromagnetism of Ni2+xMnGa1−x and Co2VGa Heusler Alloys

Origin of heterogeneous magnetostriction: A case study of nanoprecipitates-bearing Fe-Mo alloys

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Forced magnetostriction of ferromagnetic Heusler alloy Ni2MnGa at the Curie temperature

Cited by 10 publications

References 13 publications

The Characteristic Properties of Magnetostriction and Magneto-Volume Effects of Ni2MnGa-Type Ferromagnetic Heusler Alloys

The Characteristic Properties of Magnetostriction and Magneto-Volume Effects of Ni2MnGa-Type Ferromagnetic Heusler Alloys

Investigation of the Itinerant Electron Ferromagnetism of Ni2+xMnGa1−x and Co2VGa Heusler Alloys

Origin of heterogeneous magnetostriction: A case study of nanoprecipitates-bearing Fe-Mo alloys

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Forced magnetostriction of ferromagnetic Heusler alloy Ni₂MnGa at the Curie temperature