Next Article in Journal
Numerical Simulation of Thermal Processes in a Domain of Thin Metal Film Subjected to an Ultrashort Laser Pulse
Previous Article in Journal
Influence of Manufacturing Mechanical and Thermal Histories on Dimensional Stabilities of FR4 Laminate and FR4/Cu-Plated Holes
Article Menu
Issue 11 (November) cover image

Export Article

Open AccessArticle
Materials 2018, 11(11), 2115; https://doi.org/10.3390/ma11112115

Forced Magnetostrictions and Magnetizations of Ni2+xMnGa1−x at Its Curie Temperature

1
Department of Mechanical and System Engineering, Faculty of Science and Technology, Ryukoku University, Otsu, Shiga 520-2194, Japan
2
Institute for Materials Research, Tohoku University, Oarai, Ibaraki 311-1313, Japan
3
Kurume Institute of Technology, Kurume, Fukuoka 830-0052, Japan
4
Center for Advanced High Magnetic Field Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama, Toyonaka, Osaka 560-0043, Japan
5
Research Institute for Engineering and Technology, Tohoku Gakuin University, Tagajo, Miyagi 985-8537, Japan
*
Author to whom correspondence should be addressed.
Received: 16 September 2018 / Revised: 21 October 2018 / Accepted: 25 October 2018 / Published: 28 October 2018
(This article belongs to the Special Issue Fundamental Science and Applications of Highly Functional Alloys)
Full-Text   |   PDF [2156 KB, uploaded 6 November 2018]   |  

Abstract

Experimental investigations into the field dependence of magnetization and the relationship between magnetization and magnetostriction in Ni2+xMnGa1−x (x = 0.00, 0.02, 0.04) alloy ferromagnets were performed following the self-consistent renormalization (SCR) spin fluctuation theory of itinerant ferromagnetism. In this study, we investigated the magnetization of and magnetostriction on Ni2+xMnGa1−x (x = 0.02, 0.04) to check whether these relations held when the ratio of Ni to Ga and, the valence electron concentration per atom, e/a were varied. When the ratio of Ni to Ga was varied, e/a increased with increasing x. The magnetization results for x = 0.02 (e/a = 7.535) and 0.04 (e/a = 7.570) suggest that the critical index δ of HMδ is around 5.0 at the Curie temperature TC, which is the critical temperature of the ferromagnetic–paramagnetic transition. This result confirms Takahashi’s spin fluctuation theory and the experimental results of Ni2MnGa. The spontaneous magnetization pS slightly decreased with increasing x. For x = 0.00, the spin fluctuation parameter in k-space (momentum space; TA) and that in energy space (T0) were obtained. The relationship between peff/pS and TC/T0 can also be explained by Takahashi’s theory, where peff indicates the effective magnetic moments. We created a generalized Rhodes-Wohlfarth plot of peff/pS versus TC/T0 for other ferromagnets. The plot indicates that the relationship between peff/pS and T0/TC follows Takahashi’s theory. We also measured the magnetostriction for Ni2+xMnGa1−x (x = 0.02, 0.04). As a result, at TC, the plot of the magnetostriction (ΔL/L) versus M4 shows proportionality and crosses the origin. These magnetization and magnetostriction results were analyzed in terms of Takahashi’s SCR spin fluctuation theory. We investigated the magnetostriction at the premartensite phase, which is the precursor state to the martensitic transition. In Ni2MnGa system alloys, the maximum value of magnetostriction is almost proportional to the e/a. View Full-Text
Keywords: ferromagnetic Heusler alloy; magnetization; magnetostriction; itinerant electron magnetism; premartensite phase ferromagnetic Heusler alloy; magnetization; magnetostriction; itinerant electron magnetism; premartensite phase
Figures

Figure 1

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).
SciFeed

Share & Cite This Article

MDPI and ACS Style

Sakon, T.; Hayashi, Y.; Li, D.; Honda, F.; Oomi, G.; Narumi, Y.; Hagiwara, M.; Kanomata, T.; Eto, T. Forced Magnetostrictions and Magnetizations of Ni2+xMnGa1−x at Its Curie Temperature. Materials 2018, 11, 2115.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Materials EISSN 1996-1944 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top