- Email: [email protected]
Magnetization behavior of NiMnGa alloy nanowires prepared by DC electrodeposition
Journal Pre-proofs Magnetization behavior of NiMnGa alloy nanowires prepared by DC electrodeposition K. Javed, X.M. Zhang, S. Parajuli, S.S. Ali, N. Ahmad, S.A. Shah, M. Irfan, J.F. Feng, X.F. Han PII: DOI: Reference:
S0304-8853(19)33307-4 https://doi.org/10.1016/j.jmmm.2019.166232 MAGMA 166232
To appear in:
Journal of Magnetism and Magnetic Materials
Received Date: Revised Date: Accepted Date:
19 September 2019 27 November 2019 28 November 2019
Please cite this article as: K. Javed, X.M. Zhang, S. Parajuli, S.S. Ali, N. Ahmad, S.A. Shah, M. Irfan, J.F. Feng, X.F. Han, Magnetization behavior of NiMnGa alloy nanowires prepared by DC electrodeposition, Journal of Magnetism and Magnetic Materials (2019), doi: https://doi.org/10.1016/j.jmmm.2019.166232
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2019 Published by Elsevier B.V.
Magnetization behavior of NiMnGa alloy nanowires prepared by DC electrodeposition K. Javed1,2, X. M. Zhang1, S. Parajuli1, S. S. Ali1,3, N. Ahmad1,4, S. A. Shah2, M. Irfan1,5, J.F. Feng1, and X. F. Han*,1 1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences (UCAS), Beijing, 100190, China. 2. Department of Physics, Forman Christian College (A Chartered University), Lahore 54000, Pakistan. 3. Department of Physics, The University of Lahore, Lahore 54000, Pakistan 4. Department of Physics, FBAS, International Islamic University, Islamabad 44000, Pakistan 5. Department of Physics, The Islamia University of Bahawalpur, Bahawalpur,63100, Pakistan *Corresponding
author. E-mail address: [email protected] (X. F. Han).
Abstract: NiMnGa have potential applications for magnetic field sensors, strain sensors, actuators and solid-state refrigeration, due to their unique microstructures and crystalline phases at various temperatures. Synthesis of Heusler type NiMnGa nanowires (diameter ~200 nm) has been done by low cost DC electrodeposition method using AAO templates. This method was employed due to its cost effectiveness, simplicity, and precise control over composition, diameter and length of nanotubes/nanowires. It has been observed that Ga concentration decreases as Mn concentration increases with the rise in potential. Magnetic properties have been studied at room temperature as well as at low temperatures. It has been found that coercivity (Hc) increases as temperature decreases. The nanowires have maintained ferromagnetic behavior from 10 K to RT. Keywords: Nanowires; NiMnGa; FSMAs; Magneto-elastic materials. 1. Introduction During last decade and so, ferromagnetic materials having high spin polarization got great consideration of researchers because of their likely applications in the field of spintronics. Among them, Heusler alloys, due to their unique electronic structures supporting 100% spin polarization, are of particular interest [1]. Besides, certain Heusler alloys, such as NiMnFeGa and Ni2MnGa, show remarkable reversible strains under an applied magnetic field [2,3]. FSMAs (Ferromagnetic Shape Memory alloys) experience substantial shape change in a magnetic field besides stress and temperature compared to conventional shape memory alloys [4]. Although Heusler alloys share many common features with Shape Memory Alloys (SMAs), they are considered the next generation devices. Conventional SMAs show limited efficiency due to being slow with sluggish cooling. Conversely, FSMAs display larger Magnetic Field-Induced Strain (MFIS) and give quicker response at lower frequencies than the other active materials, e.g., magnetostrictive and piezoelectric substances [5]. NiMnGa has attracted wide attention due to its potential applications for magnetic field sensors, strain sensors [6], actuators [7], solid state refrigeration [8], and microcantilevers [9], due to its unique microstructure and crystalline phases at various temperatures. Ni2MnGa is thought to be the only identified substance which has martensitic transition into tetragonal structure from cubic, at TM ~ 202 K [10]. Current research on NiMn-X type alloys mostly focus on conventional arc melting synthesis that follows long duration high temperature annealing [11]. Ni2MnGa alloys have been prepared from different techniques. Bulk samples were prepared by using arc-melting, sputtering, and melt-spinning; 1
nanoparticles were synthesized using ball milling; and fibers were made by using crucible melts and glass coated microwires. In thin films, magnetically induced reorientations of martensitic variants have been reported. Nanowires are preferred, in particular, for applications that require linear size change with magnetic field [7]. Since magnetic-field-strain was observed in NiMnGa, various other FSMAs such as FePd, FePt, NiFeGa, NiMnIn, NiMnSn and NiMnSb have also been found [12]. NiMnGa system’s phase diagram mapping have been done by Takeuchi et al., in order to find FSMAs. They noticed an obvious systematic connection between the TM (transition temperature) and the Tc (Curie temperature) in a wide-ranging compositional spectrum across the ternary phase diagram. Consequently, they attributed the appearance of the martensite in the Ni–Mn–Ga system to the structural instability induced due to Ga in the antiferromagnetic/ferromagnetic transition regime in Ni1–xMnx system. Thin-film approach was employed to investigate both, the ferromagnetic behavior and mechanical characteristics of a wide range of NiMnGa ternary alloys. Takeuchi et al., introduced rapid characterization methods to measure both the mechanical and magnetic behaviors of their NiMnGa thin films. Their studies indicate that across a large regime of the phase diagram, these two properties are highly correlated [13,14]. During last several years Heusler type alloys have been investigated in detail in bulk form, thin film and nanoparticles/ingots [15-17], but only a few studies have been done on 1D (one-dimensional) Heusler type materials’ fabrication. It is generally considered that Martensitic phase transition (MPT) as well as magnetoelectronic and magnetic properties of Heusler alloys arise due to their very flexible electronic band structure [18]. It has also been confirmed by the first principles calculations based theoretical studies of Heusler FSMAs [19-21]. During last several years, 1D Ferromagnetic nanostructures have been a stimulating area of research because of their possible applications in magnetic sensors, drug delivery, ultra-small magnetic sensors and ultra-high magnetic recording media, etc. The structural and magnetic properties have been studied for ferromagnetic nanowire/nanotube arrays consisting of Ni, Co, Fe and their alloys during the last several years [22-24]. Their properties are significantly different from their thin film or bulk counter analogues. Due to their unique 1D-nanostructures and excellent properties, it is worth to synthesize and study Heusler type FSMAs 1D nanostructures. 2. Experimental Section
Fig. 1. Schematic of AAO template assisted NiMnGa NWs fabrication by DC electrodeposition. Figure 1 illustrates the schematic view of synthesis procedure. Composition of the materials plays a significant role in tailoring the martensite/austenite transformation temperatures [25]. Highly ordered nanowires (NWs) have been prepared using a low-cost electrochemical deposition method in anodic 2
aluminum oxide (AAO) templates due to its cost-effectiveness, simplicity, and precise control over composition, diameter and length of nanotubes/nanowires [23,26], as well as their magnetic and structural properties have been studied. For NWs, commercially available alumina templates (Whatman limited) with pore density of 1 X 109 pores cm-2, diameter 200 nm and thickness 60 µm, have been used. One side of template has been sputtered with gold (approx. 200 nm) as working electrode. A conventional three electrode cell was used at room temperature (RT) potentiostatically without any stirring during the electrodeposition. A SC (saturated calomel) has been used as a reference electrode whereas platinum strip has been used as counter electrode. In order to tune the nanowires composition, the applied deposition potential for different samples was varied from -1.15 to -1.35 V (vs. SCE). Length of all the nanowires was kept almost constant by tuning the deposition time. The compositions of NiMnGa alloy nanowires were tuned by controlling the concentration and deposition potential. The electrolytic solution contains NiCl2.6H2O, MnCl2.4H2O, Ga2(SO4)3.H2O and H3BO3 in the required ratio. 3. Results and Discussion The variation in elemental composition with potential for a particular solution concentration has been shown in figure 2. It has been seen that with the increase in deposition potential there is an increase in Mn concentration and decrease in Ga contents. So careful optimization of concentration and potential is required to get the required ratio of Ni, Mn and Ga.
Fig. 2. (Color online) NiMnGa nanowires’ composition VS deposition potential. Figure 3 shows the surface morphology of nanowires and EDS analysis. We have prepared several samples by optimizing the concentration and potential, and selected five samples for further analysis as Ni70+xMn5Ga25-x (x: 0, 10, 15, 20 and 25), to study the effect due to variation in Ga concentration. For example, the NWs have the stoichiometry Ni2.8Mn0.2Ga1.0, with ratio of Ni, Mn, and Ga from the EDX spectrum corresponds to 70:5:25. It is also reported that Ni-rich nanowires exhibit a higher martensite Curie temperature Tc and transition temperature TM , as compared with Mn-rich compositions in which Mn-Mn antiferromagnetic interactions can lead to lower Tc [27]. By optimization of NiMnGa composition, the TM and Tc can be adjusted near RT where large strain response can be achieved [28]. Different properties can be realized by changing the relation between TM and Tc making these alloys potential candidates for important applications. For example, in Ni2+xMn1-xGa (x: 0.18-0.20) the 3
structural and magnetic transition’s coupling happens as transition temperatures are very close [29]. Consequently, we can possibly achieve not only the shape memory effects under an external field, but we can also induce versatile features like magnetoresistance, magnetostriction and giant magnetoresistance, which are significant for magnetostrictive transducers and magnetic refrigeration [3,28,30-33].
Fig. 3. (a) SEM image, and (b) EDS analysis for NiMnGa NWs. X-ray diffraction spectrum at RT has been shown in figure 4. NWs exhibit a cubic crystal structure, with lattice constant of a=5.821 Å at RT. The average crystallite size estimated from XRD peaks using Scherrer equation is about 29 nm for Ni70Mn5Ga25 sample. A report on sputtering of Ni2MnGa showed that Mn and Ga inhibited in non-stoichiometric ratio in as-deposited thin films [34,35].
Fig. 4. (Color online) XRD patterns of NiMnGa NWs with different compositions. Figure 5(a) shows the M-H loop for Ni70Mn5Ga25 (Ni2.8Mn0.2Ga1.0) sample at RT. Closed packed structure of NWs in AAO leads to stronger dipolar coupling among the wires, and so the shape anisotropy is not that significant enough to induce easy magnetization precisely along the NWs axis. The coercivity Hc, Squareness SQ, and Ms variation for samples with different Ga concentrations has been shown in figure 5(b), 5(c), and 5(d), respectively. Another reason for the less dominancy of shape anisotropy is the length of NWs showing a lesser anisotropic behavior. The total effective anisotropic field can be written as 𝐿 (1) 𝐻𝑘 = 2𝜋𝑀𝑠 ―6.3𝜋𝑀𝑠𝑟2𝐷3 + 𝐻𝑚𝑎 4
This equation has three parts; shape anisotropy field, magnetostatic dipole interaction field, and magnetocrystalline anisotropy respectively. The anisotropy field Hk mainly controls the alignment of easy axis. The easy axis aligns parallel to NWs axis when Hk is positive and vice versa [36-38]. The nanostructures prepared by electrodeposition are normally poly-crystalline and/or amorphous, for which Hma (magneto-crystalline anisotropy) will be negligible [23]. Ms Measurements have shown that there is sharp rise as Ga concentration wt. % >10, as shown in figure 5(d).
Fig. 5. (Color online) (a) MH Curves at RT. Composition dependence of (b) coercivity (Hc), (c) squareness (SQ), and (d) saturation magnetization (Ms). Due to the TM increasing drastically with the increasing 𝓍, it can be suggested that alloys with large Ni concentration can be employed as high-temperature SMAs. However, a better understanding of the physical phenomenon is still required to design new advanced materials. NiMnGa system’s phase diagram has been mapped to find new SMAs as well as to find systematic relation between Tc and TM in a wide range of compositions [13]. It is to be noted that the prepared Ni-rich NiMnGa nanowires demonstrate the martensite and ferromagnetic transition temperatures above 300 K. Martensitic transition (MT) is a phase transition related to the structure changes, which is further related to a first order transition. In the thermal magnetization curve, a sudden variation in magnetization is related to MT as proved by many previous reports [39,40]. Very recently, Recarte et al. also reported the MT temperatures Ms = 573 K (Martensite start), and Mf = 485 K (Martensite finish) for Ni50Mn26Ga20Co4 ingots, i.e. above room temperature [41]. The MT in Ni-Mn-X alloys (where X = Sn, Ga, Sb, and In) occurs from a cubic austenitic phase, showing L21 Heusler crystal structure and next-nearest neighbor atomic order, to a low-symmetry martensitic structure [42,43]. 5
M-H loops of Ni70Mn5Ga25 (Ni2.8Mn0.2Ga1.0) NWs at different temperatures have been shown in Figure 6(a). Figure 6(b) has shown the magnetic moments’ temperature dependence in ZFC (zero field cooled) and FC (field cooled) modes for Ni2.8Mn0.2Ga1.0 (Ni70Mn5Ga25) sample, with 400 Oe applied field. Ni-rich NiMnGa NWs have shown ferromagnetic behavior from 300 K to 10 K. Figure 6(c) demonstrates the Hc and Ms temperature dependence. Coercivity Hc increased from 41 Oe (at 300 K) to 156 Oe (at 10 K). The stoichiometric Ni2MnGa is FM with Tc ~ 376 K [6]. The increase in coercivity with the decrease in temperature can be attributed to the thermal relaxation over the anisotropy energy barrier [44,45]. The curves in figure 6(b) illustrates some characteristics e.g. irreversible nature has been observed below blocking temperature (TB) having MZFC < MFC. It has been believed that superparamagnetic behavior is responsible for such features [46]. It has been reported that with the increase in temperature coercivity decreases, this behavior has been demonstrated by Kneller’s formula [47]
𝐻𝑐 = 𝐻0𝑐 (1 ―
𝑇 ) 𝑇𝐵
Where 𝐻0𝑐 = coercivity at 0 K, and TB = blocking temperature.
Fig. 6. (Color online) (a) M-H loops of Ni70Mn5Ga25 (Ni2.8Mn0.2Ga1.0) NWs (inset shows the magnified image of coercivity region), (b) M-T curves for Ni2.8Mn0.2Ga1.0 nanowires, and (c) Hc and Ms variations, at different temperatures. 4. Conclusions 6
In summary, Ni-Mn-Ga nanowires have been prepared via DC electrodeposition method in AAO membranes with ~200 nm diameter. Nanowires exhibited a cubic crystal structure. The Ga concentration decreases as Mn concentration increases with the rise in potential. Also, it has been found that coercivity Hc increases as temperature decreases. This shows that co-deposition of Mn and Ga by electrochemical method is difficult. The nanowires have maintained ferromagnetic behavior from 10 K to RT. These Ni rich Ni-Mn-Ga nanowires have both TM and Tc above RT, it makes these nanowires attractive for high temperature shape memory alloy applications. Acknowledgments This work has been supported by the NSFC-PSF joint project [NSFC No 51761145110], National Key Research and Development Program of China [MOST, Grants No. 2017YFA0206200], the National Natural Science Foundation of China [NSFC, Grants No. 11434014 and No. 51831012], and partially supported by the International Partnership Program (Grant No. 112111KYSB20170090), and the Key Research Program of Frontier Sciences (Grant No. QYZDJ-SSWSLH016) of the Chinese Academy of Sciences (CAS). References 1.
Z. H. Liu, X. Q. Ma, Z. Y. Zhu, H. Z. Luo, G. D. Liu, J. L. Chen, G. H. Wu, X. Zhang, J. Q. Xiao, J. Mag. Magn. Mater., 323, (2011) 2192.
2.
G. H. Wu, W. H. Wang., J. L. Chen, Z. H. Liu, W. S. Zhan, T. Liang, H. B. Xu, Appl. Phys. Lett., 80, (2002) 634.
3.
S. J. Murray, M. Marioni, S. M. Allen, R. C. O’Handley, T. A. Lograsso, Appl. Phys. Lett., 77, (2000) 886.
4.
K. Ullakko, J. K. Huang., C. Kantner, R. C. O’Handley, V. V. Kokorin, Appl. Phys. Lett., 69, (1996) 1966.
5.
R. J. Rani, R. S. Pandi., S. Seenithurai, S. V. Kumar, M. Muthuraman, M. Mahendran, American Journal of Condensed Matter Physics, 1, (2011) 1.
6.
A. N. Vasilev, V. D. Buchelnikov, T. Takagie, V. V. Khovailo, E. I. Estrin, Phys. Usp., 46, (2003) 559.
7.
S. A. Wilson, et. al., Materials Science and Engineering: R: Reports, 56, (2007) 1.
8.
A. A. Cherechukin, T. Takagi, M. Matsumoto, V. D. Buchelnikov, Physics Letters A, 326, (2004) 146.
9.
S. Singh, S. Bhardwaj, A. K. Panda, V. K. Ahire, A. Mitra, A. M. Awasthi, S. R. Barman, Materials Science Forum, 635, (2009) 43.
10.
Y. Ma, S. Awaji, K. Watanabe, M. Matsumoto, N. Kobayashi, Solid State Commun., 113, (2000) 671.
11.
Y. Zhang, L. Zhang, Q. Zheng, X. Zheng, M. Li, J. Du, A. Yan, Sci. Rep. 5, (2015) 11010.
12.
R. Kainuma, et. al., Nature, 439, (2006) 957.
13.
I. Takeuchi, O. O. Famodu, J. C. Read, M. A. Aronova, K.-S. Chang, C. Craciunescu, et al., Nature Materials, 2, (2003) 180.
14.
R. W. Cahn, Nature Materials, 2, (2003) 141.
15.
L. Straka, A. Sozinov, J. Drahokoupil, V. Kopecky, H. Hanninen, O. Heczko, J. Appl. Phys. 114, (2013) 063504.
16.
R. Santamarta, E. Cesari, J. Font, J. Muntasell, J. Pons, J. Dutkiewicz, Scripta Materialia, 54, (2006) 1985.
17.
R. Aseguinolaza, V. Golub, J. M. Barandiaran, M. Ohtsuka, P. Mullner, O. Y. Salyuk, V. A. Chernenko, Appl. Phys. Lett. 102, (2013) 182401.
18.
K. Sumida, K. Shirai, S. Zhu, M. Taniguchi, M. Ye, S. Ueda, Y. Takeda, Y. Saitoh, I. R. Aseguinolaza, J. M. Barandiaran, V. A. Chernenko, A. Kimura, Phys. Rev. B, 91, (2015) 134417.
19.
M. A. Uijttewaal, T. Hickel, J. Neugebauer, M. E. Gruner, P. Entel, Phys. Rev. Lett., 102, (2009) 035702.
20.
S. R. Barman, S. Banik, A. Chakrabarti, Phys. Rev. B, 72, (2005) 184410.
7
21.
M. B. Sahariah, S. Ghosh, C. S. Singh, S. Gowtham, R. Pandey, J. Phys.: Condens. Matter., 25, (2013) 025502.
22.
S. Shamaila, D. P. Liu, R. Sharif, J. Y. Chen, H. R. Liu, X. F. Han, Appl. Phys. Lett., 94, (2009) 203101.
23.
X. F. Han, S. Shamaila, R. Sharif, J. Y. Chen, H. R. Liu, D. P. Liu, Adv. Mater., 21, (2009) 4619.
24.
D. W. Shi, K. Javed, S. S. Ali, J. Y. Chen, P. S. Li, Y. G. Zhao, X. F. Han, Nanoscale, 6, (2014) 7215.
25.
J. Pons, V. A. Chernenko, R. Santamarta, E. Cesari, Acta Materialia, 48, (2000) 3027.
26.
N. Ahmad, J. Y. Chen, D. W. Shi, J. Iqbal, X. F. Han, J. Appl. Phys., 111, (2012) 07C119.
27.
S. Banik, et. al., Phys. Rev. B., 75, (2007) 104107.
28.
A. Sozinov, A. A. Likhachev, N. Lanska, K. Ullakko, Appl. Phys. Lett., 80, (2002) 1746.
29.
V. V. Khovaylo, V. D. Buchelnikov, R. Kainuma, V. V. Koledov, M. Ohtsuka, V. G. Shavrov, T. Takagi, S. V. Taskaev, A. N. Vasiliev, Phys. Rev. B., 72, (2005) 224408.
30.
J. Marcos, L. Manosa, A. Planes, F. Casanova, X. Batlle, A. Labarta, Phys. Rev. B., 68, (2003) 094401.
31.
X. Zhou, W. Li, H. P. Kunkel, G. Williams, A J. Phys.: Condens. Matter, 16, (2004) L39.
32.
V. K. Sharma, M. K. Chattopadhyat, K. H. B. Shaeb, A. Chouhan, S. B. Roy, Appl. Phys. Lett., 89, (2006) 222509.
33.
C. M. Li, H. B. Luo, Q. M. Hu, R. Yang, B. Johansson, L. Vitos, Phys. Rev. B., 82, (2010) 024201.
34.
Y. Luo, P. Leicht, A. Laptev, M. Fonin, U. Rudiger, M. Laufenberg, K. Samwer, New J. Phys., 13, (2011) 013042.
35.
A. Backen, S. R. Yeduru, M. Kohl, S. Baunack, A. Diestel, B. Holzapfel, L. Schultz, S. Fähler, Acta Materialia, 58, (2010) 3415.
36.
J. Y. Chen, H. R. Liu, N. Ahmad, Y. L. Li, Z. Y. Chen, W. P. Zhou, X. F. Han, J. Appl. Phys., 109, (2011) 07E157.
37.
G. C. Han, B. Y. Zong, P. Luo, Y. H. Wu, J. Appl. Phys., 93, (2003) 9202.
38.
B. Nirmala, K. V. Peruman, R. Amuthan, M. Mahendran, Nanoscience and Nanotechnology, 1, (2011) 8.
39.
P. J. Shamberger, F. Ohuchi, Phys. Rev. B., 79, (2009) 144407.
40.
Y. Zhang, et al.; Scripta Mater., 75, (2014) 26.
41.
V. Recarte, J. I. Perez-Landazabal, V. Sanchez-Alarcos, A. Rodriguez-Velamazan, Journal of Physics: Conference
42.
Series, 549, (2014) 012017. V. Buchelnikov, and V. Sokolovskiy, The Physics of Metals and Metallography, 112, (2011) 633.
43.
V. Sokolovskiy, et al., Phys. Rev. B, 86, (2012) 134418.
44.
S. Shamaila, R. Sharif, S. Riaz, Khaleeq-ur-Rahman, M., X. F. Han, J. Magn. Magn. Mater., 320, (2008) 1803.
45.
J. Sort, V. Langlais, S. Doppiu, B. Dieny, S. Surinach, J. S. Munoz, M. D. Baró, C. H. Laurent, J. Nogues, Nanotechnology, 15, (2004) S211.
46.
R. D. Sanchez, J. Rivas, P. Vaqueiro, M. A. Lopez-Quintela, D. Caeiro, J. Magn. Magn. Mater., 247, (2002) 92.
47.
D. T. T. Nguyet, N. P. Duong, T. L. N. Anh, T. D. Hien, J. Alloys Compd. 541, (2012) 18.
8
Author Contribution Statement X. F. Han and K. Javed conceived the idea and designed the experiments. K. Javed, X. M. Zhang, S. Parajuli, S. S. Ali, N. Ahmad, and M. Irfan were responsible for experiments, measurements and data analysis. X. F. Han, J. F, Feng, and S. A. Shah reviewed and commented on the paper. All authors discussed the results and commented on the manuscript.
9
Author Contribution Statement X. F. Han and K. Javed conceived the idea and designed the experiments. K. Javed, X. M. Zhang, S. Parajuli, S. S. Ali, N. Ahmad, and M. Irfan were responsible for experiments, measurements and data analysis. X. F. Han, J. F, Feng, and S. A. Shah reviewed and commented on the paper. All authors discussed the results and commented on the manuscript.
10
Highlights 1. Highly order NiMnGa alloy nanowires have been fabricated by simple and low-cost DC electrodeposition with different compositions. 2. With the increase in deposition potential there is an increase in Mn concentration and decrease in Ga contents. 3. Magnetic properties of NiMnGa nanowires can be modified by changing its composition. 4. A linear dependence of coercivity on temperature has been found for Ni2.8Mn0.2Ga1.0 sample.
11
S0304-8853(19)33307-4 https://doi.org/10.1016/j.jmmm.2019.166232 MAGMA 166232
To appear in:
Journal of Magnetism and Magnetic Materials
Received Date: Revised Date: Accepted Date:
19 September 2019 27 November 2019 28 November 2019
Please cite this article as: K. Javed, X.M. Zhang, S. Parajuli, S.S. Ali, N. Ahmad, S.A. Shah, M. Irfan, J.F. Feng, X.F. Han, Magnetization behavior of NiMnGa alloy nanowires prepared by DC electrodeposition, Journal of Magnetism and Magnetic Materials (2019), doi: https://doi.org/10.1016/j.jmmm.2019.166232
This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
© 2019 Published by Elsevier B.V.
Magnetization behavior of NiMnGa alloy nanowires prepared by DC electrodeposition K. Javed1,2, X. M. Zhang1, S. Parajuli1, S. S. Ali1,3, N. Ahmad1,4, S. A. Shah2, M. Irfan1,5, J.F. Feng1, and X. F. Han*,1 1. Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences (UCAS), Beijing, 100190, China. 2. Department of Physics, Forman Christian College (A Chartered University), Lahore 54000, Pakistan. 3. Department of Physics, The University of Lahore, Lahore 54000, Pakistan 4. Department of Physics, FBAS, International Islamic University, Islamabad 44000, Pakistan 5. Department of Physics, The Islamia University of Bahawalpur, Bahawalpur,63100, Pakistan *Corresponding
author. E-mail address: [email protected] (X. F. Han).
Abstract: NiMnGa have potential applications for magnetic field sensors, strain sensors, actuators and solid-state refrigeration, due to their unique microstructures and crystalline phases at various temperatures. Synthesis of Heusler type NiMnGa nanowires (diameter ~200 nm) has been done by low cost DC electrodeposition method using AAO templates. This method was employed due to its cost effectiveness, simplicity, and precise control over composition, diameter and length of nanotubes/nanowires. It has been observed that Ga concentration decreases as Mn concentration increases with the rise in potential. Magnetic properties have been studied at room temperature as well as at low temperatures. It has been found that coercivity (Hc) increases as temperature decreases. The nanowires have maintained ferromagnetic behavior from 10 K to RT. Keywords: Nanowires; NiMnGa; FSMAs; Magneto-elastic materials. 1. Introduction During last decade and so, ferromagnetic materials having high spin polarization got great consideration of researchers because of their likely applications in the field of spintronics. Among them, Heusler alloys, due to their unique electronic structures supporting 100% spin polarization, are of particular interest [1]. Besides, certain Heusler alloys, such as NiMnFeGa and Ni2MnGa, show remarkable reversible strains under an applied magnetic field [2,3]. FSMAs (Ferromagnetic Shape Memory alloys) experience substantial shape change in a magnetic field besides stress and temperature compared to conventional shape memory alloys [4]. Although Heusler alloys share many common features with Shape Memory Alloys (SMAs), they are considered the next generation devices. Conventional SMAs show limited efficiency due to being slow with sluggish cooling. Conversely, FSMAs display larger Magnetic Field-Induced Strain (MFIS) and give quicker response at lower frequencies than the other active materials, e.g., magnetostrictive and piezoelectric substances [5]. NiMnGa has attracted wide attention due to its potential applications for magnetic field sensors, strain sensors [6], actuators [7], solid state refrigeration [8], and microcantilevers [9], due to its unique microstructure and crystalline phases at various temperatures. Ni2MnGa is thought to be the only identified substance which has martensitic transition into tetragonal structure from cubic, at TM ~ 202 K [10]. Current research on NiMn-X type alloys mostly focus on conventional arc melting synthesis that follows long duration high temperature annealing [11]. Ni2MnGa alloys have been prepared from different techniques. Bulk samples were prepared by using arc-melting, sputtering, and melt-spinning; 1
nanoparticles were synthesized using ball milling; and fibers were made by using crucible melts and glass coated microwires. In thin films, magnetically induced reorientations of martensitic variants have been reported. Nanowires are preferred, in particular, for applications that require linear size change with magnetic field [7]. Since magnetic-field-strain was observed in NiMnGa, various other FSMAs such as FePd, FePt, NiFeGa, NiMnIn, NiMnSn and NiMnSb have also been found [12]. NiMnGa system’s phase diagram mapping have been done by Takeuchi et al., in order to find FSMAs. They noticed an obvious systematic connection between the TM (transition temperature) and the Tc (Curie temperature) in a wide-ranging compositional spectrum across the ternary phase diagram. Consequently, they attributed the appearance of the martensite in the Ni–Mn–Ga system to the structural instability induced due to Ga in the antiferromagnetic/ferromagnetic transition regime in Ni1–xMnx system. Thin-film approach was employed to investigate both, the ferromagnetic behavior and mechanical characteristics of a wide range of NiMnGa ternary alloys. Takeuchi et al., introduced rapid characterization methods to measure both the mechanical and magnetic behaviors of their NiMnGa thin films. Their studies indicate that across a large regime of the phase diagram, these two properties are highly correlated [13,14]. During last several years Heusler type alloys have been investigated in detail in bulk form, thin film and nanoparticles/ingots [15-17], but only a few studies have been done on 1D (one-dimensional) Heusler type materials’ fabrication. It is generally considered that Martensitic phase transition (MPT) as well as magnetoelectronic and magnetic properties of Heusler alloys arise due to their very flexible electronic band structure [18]. It has also been confirmed by the first principles calculations based theoretical studies of Heusler FSMAs [19-21]. During last several years, 1D Ferromagnetic nanostructures have been a stimulating area of research because of their possible applications in magnetic sensors, drug delivery, ultra-small magnetic sensors and ultra-high magnetic recording media, etc. The structural and magnetic properties have been studied for ferromagnetic nanowire/nanotube arrays consisting of Ni, Co, Fe and their alloys during the last several years [22-24]. Their properties are significantly different from their thin film or bulk counter analogues. Due to their unique 1D-nanostructures and excellent properties, it is worth to synthesize and study Heusler type FSMAs 1D nanostructures. 2. Experimental Section
Fig. 1. Schematic of AAO template assisted NiMnGa NWs fabrication by DC electrodeposition. Figure 1 illustrates the schematic view of synthesis procedure. Composition of the materials plays a significant role in tailoring the martensite/austenite transformation temperatures [25]. Highly ordered nanowires (NWs) have been prepared using a low-cost electrochemical deposition method in anodic 2
aluminum oxide (AAO) templates due to its cost-effectiveness, simplicity, and precise control over composition, diameter and length of nanotubes/nanowires [23,26], as well as their magnetic and structural properties have been studied. For NWs, commercially available alumina templates (Whatman limited) with pore density of 1 X 109 pores cm-2, diameter 200 nm and thickness 60 µm, have been used. One side of template has been sputtered with gold (approx. 200 nm) as working electrode. A conventional three electrode cell was used at room temperature (RT) potentiostatically without any stirring during the electrodeposition. A SC (saturated calomel) has been used as a reference electrode whereas platinum strip has been used as counter electrode. In order to tune the nanowires composition, the applied deposition potential for different samples was varied from -1.15 to -1.35 V (vs. SCE). Length of all the nanowires was kept almost constant by tuning the deposition time. The compositions of NiMnGa alloy nanowires were tuned by controlling the concentration and deposition potential. The electrolytic solution contains NiCl2.6H2O, MnCl2.4H2O, Ga2(SO4)3.H2O and H3BO3 in the required ratio. 3. Results and Discussion The variation in elemental composition with potential for a particular solution concentration has been shown in figure 2. It has been seen that with the increase in deposition potential there is an increase in Mn concentration and decrease in Ga contents. So careful optimization of concentration and potential is required to get the required ratio of Ni, Mn and Ga.
Fig. 2. (Color online) NiMnGa nanowires’ composition VS deposition potential. Figure 3 shows the surface morphology of nanowires and EDS analysis. We have prepared several samples by optimizing the concentration and potential, and selected five samples for further analysis as Ni70+xMn5Ga25-x (x: 0, 10, 15, 20 and 25), to study the effect due to variation in Ga concentration. For example, the NWs have the stoichiometry Ni2.8Mn0.2Ga1.0, with ratio of Ni, Mn, and Ga from the EDX spectrum corresponds to 70:5:25. It is also reported that Ni-rich nanowires exhibit a higher martensite Curie temperature Tc and transition temperature TM , as compared with Mn-rich compositions in which Mn-Mn antiferromagnetic interactions can lead to lower Tc [27]. By optimization of NiMnGa composition, the TM and Tc can be adjusted near RT where large strain response can be achieved [28]. Different properties can be realized by changing the relation between TM and Tc making these alloys potential candidates for important applications. For example, in Ni2+xMn1-xGa (x: 0.18-0.20) the 3
structural and magnetic transition’s coupling happens as transition temperatures are very close [29]. Consequently, we can possibly achieve not only the shape memory effects under an external field, but we can also induce versatile features like magnetoresistance, magnetostriction and giant magnetoresistance, which are significant for magnetostrictive transducers and magnetic refrigeration [3,28,30-33].
Fig. 3. (a) SEM image, and (b) EDS analysis for NiMnGa NWs. X-ray diffraction spectrum at RT has been shown in figure 4. NWs exhibit a cubic crystal structure, with lattice constant of a=5.821 Å at RT. The average crystallite size estimated from XRD peaks using Scherrer equation is about 29 nm for Ni70Mn5Ga25 sample. A report on sputtering of Ni2MnGa showed that Mn and Ga inhibited in non-stoichiometric ratio in as-deposited thin films [34,35].
Fig. 4. (Color online) XRD patterns of NiMnGa NWs with different compositions. Figure 5(a) shows the M-H loop for Ni70Mn5Ga25 (Ni2.8Mn0.2Ga1.0) sample at RT. Closed packed structure of NWs in AAO leads to stronger dipolar coupling among the wires, and so the shape anisotropy is not that significant enough to induce easy magnetization precisely along the NWs axis. The coercivity Hc, Squareness SQ, and Ms variation for samples with different Ga concentrations has been shown in figure 5(b), 5(c), and 5(d), respectively. Another reason for the less dominancy of shape anisotropy is the length of NWs showing a lesser anisotropic behavior. The total effective anisotropic field can be written as 𝐿 (1) 𝐻𝑘 = 2𝜋𝑀𝑠 ―6.3𝜋𝑀𝑠𝑟2𝐷3 + 𝐻𝑚𝑎 4
This equation has three parts; shape anisotropy field, magnetostatic dipole interaction field, and magnetocrystalline anisotropy respectively. The anisotropy field Hk mainly controls the alignment of easy axis. The easy axis aligns parallel to NWs axis when Hk is positive and vice versa [36-38]. The nanostructures prepared by electrodeposition are normally poly-crystalline and/or amorphous, for which Hma (magneto-crystalline anisotropy) will be negligible [23]. Ms Measurements have shown that there is sharp rise as Ga concentration wt. % >10, as shown in figure 5(d).
Fig. 5. (Color online) (a) MH Curves at RT. Composition dependence of (b) coercivity (Hc), (c) squareness (SQ), and (d) saturation magnetization (Ms). Due to the TM increasing drastically with the increasing 𝓍, it can be suggested that alloys with large Ni concentration can be employed as high-temperature SMAs. However, a better understanding of the physical phenomenon is still required to design new advanced materials. NiMnGa system’s phase diagram has been mapped to find new SMAs as well as to find systematic relation between Tc and TM in a wide range of compositions [13]. It is to be noted that the prepared Ni-rich NiMnGa nanowires demonstrate the martensite and ferromagnetic transition temperatures above 300 K. Martensitic transition (MT) is a phase transition related to the structure changes, which is further related to a first order transition. In the thermal magnetization curve, a sudden variation in magnetization is related to MT as proved by many previous reports [39,40]. Very recently, Recarte et al. also reported the MT temperatures Ms = 573 K (Martensite start), and Mf = 485 K (Martensite finish) for Ni50Mn26Ga20Co4 ingots, i.e. above room temperature [41]. The MT in Ni-Mn-X alloys (where X = Sn, Ga, Sb, and In) occurs from a cubic austenitic phase, showing L21 Heusler crystal structure and next-nearest neighbor atomic order, to a low-symmetry martensitic structure [42,43]. 5
M-H loops of Ni70Mn5Ga25 (Ni2.8Mn0.2Ga1.0) NWs at different temperatures have been shown in Figure 6(a). Figure 6(b) has shown the magnetic moments’ temperature dependence in ZFC (zero field cooled) and FC (field cooled) modes for Ni2.8Mn0.2Ga1.0 (Ni70Mn5Ga25) sample, with 400 Oe applied field. Ni-rich NiMnGa NWs have shown ferromagnetic behavior from 300 K to 10 K. Figure 6(c) demonstrates the Hc and Ms temperature dependence. Coercivity Hc increased from 41 Oe (at 300 K) to 156 Oe (at 10 K). The stoichiometric Ni2MnGa is FM with Tc ~ 376 K [6]. The increase in coercivity with the decrease in temperature can be attributed to the thermal relaxation over the anisotropy energy barrier [44,45]. The curves in figure 6(b) illustrates some characteristics e.g. irreversible nature has been observed below blocking temperature (TB) having MZFC < MFC. It has been believed that superparamagnetic behavior is responsible for such features [46]. It has been reported that with the increase in temperature coercivity decreases, this behavior has been demonstrated by Kneller’s formula [47]
𝐻𝑐 = 𝐻0𝑐 (1 ―
𝑇 ) 𝑇𝐵
Where 𝐻0𝑐 = coercivity at 0 K, and TB = blocking temperature.
Fig. 6. (Color online) (a) M-H loops of Ni70Mn5Ga25 (Ni2.8Mn0.2Ga1.0) NWs (inset shows the magnified image of coercivity region), (b) M-T curves for Ni2.8Mn0.2Ga1.0 nanowires, and (c) Hc and Ms variations, at different temperatures. 4. Conclusions 6
In summary, Ni-Mn-Ga nanowires have been prepared via DC electrodeposition method in AAO membranes with ~200 nm diameter. Nanowires exhibited a cubic crystal structure. The Ga concentration decreases as Mn concentration increases with the rise in potential. Also, it has been found that coercivity Hc increases as temperature decreases. This shows that co-deposition of Mn and Ga by electrochemical method is difficult. The nanowires have maintained ferromagnetic behavior from 10 K to RT. These Ni rich Ni-Mn-Ga nanowires have both TM and Tc above RT, it makes these nanowires attractive for high temperature shape memory alloy applications. Acknowledgments This work has been supported by the NSFC-PSF joint project [NSFC No 51761145110], National Key Research and Development Program of China [MOST, Grants No. 2017YFA0206200], the National Natural Science Foundation of China [NSFC, Grants No. 11434014 and No. 51831012], and partially supported by the International Partnership Program (Grant No. 112111KYSB20170090), and the Key Research Program of Frontier Sciences (Grant No. QYZDJ-SSWSLH016) of the Chinese Academy of Sciences (CAS). References 1.
Z. H. Liu, X. Q. Ma, Z. Y. Zhu, H. Z. Luo, G. D. Liu, J. L. Chen, G. H. Wu, X. Zhang, J. Q. Xiao, J. Mag. Magn. Mater., 323, (2011) 2192.
2.
G. H. Wu, W. H. Wang., J. L. Chen, Z. H. Liu, W. S. Zhan, T. Liang, H. B. Xu, Appl. Phys. Lett., 80, (2002) 634.
3.
S. J. Murray, M. Marioni, S. M. Allen, R. C. O’Handley, T. A. Lograsso, Appl. Phys. Lett., 77, (2000) 886.
4.
K. Ullakko, J. K. Huang., C. Kantner, R. C. O’Handley, V. V. Kokorin, Appl. Phys. Lett., 69, (1996) 1966.
5.
R. J. Rani, R. S. Pandi., S. Seenithurai, S. V. Kumar, M. Muthuraman, M. Mahendran, American Journal of Condensed Matter Physics, 1, (2011) 1.
6.
A. N. Vasilev, V. D. Buchelnikov, T. Takagie, V. V. Khovailo, E. I. Estrin, Phys. Usp., 46, (2003) 559.
7.
S. A. Wilson, et. al., Materials Science and Engineering: R: Reports, 56, (2007) 1.
8.
A. A. Cherechukin, T. Takagi, M. Matsumoto, V. D. Buchelnikov, Physics Letters A, 326, (2004) 146.
9.
S. Singh, S. Bhardwaj, A. K. Panda, V. K. Ahire, A. Mitra, A. M. Awasthi, S. R. Barman, Materials Science Forum, 635, (2009) 43.
10.
Y. Ma, S. Awaji, K. Watanabe, M. Matsumoto, N. Kobayashi, Solid State Commun., 113, (2000) 671.
11.
Y. Zhang, L. Zhang, Q. Zheng, X. Zheng, M. Li, J. Du, A. Yan, Sci. Rep. 5, (2015) 11010.
12.
R. Kainuma, et. al., Nature, 439, (2006) 957.
13.
I. Takeuchi, O. O. Famodu, J. C. Read, M. A. Aronova, K.-S. Chang, C. Craciunescu, et al., Nature Materials, 2, (2003) 180.
14.
R. W. Cahn, Nature Materials, 2, (2003) 141.
15.
L. Straka, A. Sozinov, J. Drahokoupil, V. Kopecky, H. Hanninen, O. Heczko, J. Appl. Phys. 114, (2013) 063504.
16.
R. Santamarta, E. Cesari, J. Font, J. Muntasell, J. Pons, J. Dutkiewicz, Scripta Materialia, 54, (2006) 1985.
17.
R. Aseguinolaza, V. Golub, J. M. Barandiaran, M. Ohtsuka, P. Mullner, O. Y. Salyuk, V. A. Chernenko, Appl. Phys. Lett. 102, (2013) 182401.
18.
K. Sumida, K. Shirai, S. Zhu, M. Taniguchi, M. Ye, S. Ueda, Y. Takeda, Y. Saitoh, I. R. Aseguinolaza, J. M. Barandiaran, V. A. Chernenko, A. Kimura, Phys. Rev. B, 91, (2015) 134417.
19.
M. A. Uijttewaal, T. Hickel, J. Neugebauer, M. E. Gruner, P. Entel, Phys. Rev. Lett., 102, (2009) 035702.
20.
S. R. Barman, S. Banik, A. Chakrabarti, Phys. Rev. B, 72, (2005) 184410.
7
21.
M. B. Sahariah, S. Ghosh, C. S. Singh, S. Gowtham, R. Pandey, J. Phys.: Condens. Matter., 25, (2013) 025502.
22.
S. Shamaila, D. P. Liu, R. Sharif, J. Y. Chen, H. R. Liu, X. F. Han, Appl. Phys. Lett., 94, (2009) 203101.
23.
X. F. Han, S. Shamaila, R. Sharif, J. Y. Chen, H. R. Liu, D. P. Liu, Adv. Mater., 21, (2009) 4619.
24.
D. W. Shi, K. Javed, S. S. Ali, J. Y. Chen, P. S. Li, Y. G. Zhao, X. F. Han, Nanoscale, 6, (2014) 7215.
25.
J. Pons, V. A. Chernenko, R. Santamarta, E. Cesari, Acta Materialia, 48, (2000) 3027.
26.
N. Ahmad, J. Y. Chen, D. W. Shi, J. Iqbal, X. F. Han, J. Appl. Phys., 111, (2012) 07C119.
27.
S. Banik, et. al., Phys. Rev. B., 75, (2007) 104107.
28.
A. Sozinov, A. A. Likhachev, N. Lanska, K. Ullakko, Appl. Phys. Lett., 80, (2002) 1746.
29.
V. V. Khovaylo, V. D. Buchelnikov, R. Kainuma, V. V. Koledov, M. Ohtsuka, V. G. Shavrov, T. Takagi, S. V. Taskaev, A. N. Vasiliev, Phys. Rev. B., 72, (2005) 224408.
30.
J. Marcos, L. Manosa, A. Planes, F. Casanova, X. Batlle, A. Labarta, Phys. Rev. B., 68, (2003) 094401.
31.
X. Zhou, W. Li, H. P. Kunkel, G. Williams, A J. Phys.: Condens. Matter, 16, (2004) L39.
32.
V. K. Sharma, M. K. Chattopadhyat, K. H. B. Shaeb, A. Chouhan, S. B. Roy, Appl. Phys. Lett., 89, (2006) 222509.
33.
C. M. Li, H. B. Luo, Q. M. Hu, R. Yang, B. Johansson, L. Vitos, Phys. Rev. B., 82, (2010) 024201.
34.
Y. Luo, P. Leicht, A. Laptev, M. Fonin, U. Rudiger, M. Laufenberg, K. Samwer, New J. Phys., 13, (2011) 013042.
35.
A. Backen, S. R. Yeduru, M. Kohl, S. Baunack, A. Diestel, B. Holzapfel, L. Schultz, S. Fähler, Acta Materialia, 58, (2010) 3415.
36.
J. Y. Chen, H. R. Liu, N. Ahmad, Y. L. Li, Z. Y. Chen, W. P. Zhou, X. F. Han, J. Appl. Phys., 109, (2011) 07E157.
37.
G. C. Han, B. Y. Zong, P. Luo, Y. H. Wu, J. Appl. Phys., 93, (2003) 9202.
38.
B. Nirmala, K. V. Peruman, R. Amuthan, M. Mahendran, Nanoscience and Nanotechnology, 1, (2011) 8.
39.
P. J. Shamberger, F. Ohuchi, Phys. Rev. B., 79, (2009) 144407.
40.
Y. Zhang, et al.; Scripta Mater., 75, (2014) 26.
41.
V. Recarte, J. I. Perez-Landazabal, V. Sanchez-Alarcos, A. Rodriguez-Velamazan, Journal of Physics: Conference
42.
Series, 549, (2014) 012017. V. Buchelnikov, and V. Sokolovskiy, The Physics of Metals and Metallography, 112, (2011) 633.
43.
V. Sokolovskiy, et al., Phys. Rev. B, 86, (2012) 134418.
44.
S. Shamaila, R. Sharif, S. Riaz, Khaleeq-ur-Rahman, M., X. F. Han, J. Magn. Magn. Mater., 320, (2008) 1803.
45.
J. Sort, V. Langlais, S. Doppiu, B. Dieny, S. Surinach, J. S. Munoz, M. D. Baró, C. H. Laurent, J. Nogues, Nanotechnology, 15, (2004) S211.
46.
R. D. Sanchez, J. Rivas, P. Vaqueiro, M. A. Lopez-Quintela, D. Caeiro, J. Magn. Magn. Mater., 247, (2002) 92.
47.
D. T. T. Nguyet, N. P. Duong, T. L. N. Anh, T. D. Hien, J. Alloys Compd. 541, (2012) 18.
8
Author Contribution Statement X. F. Han and K. Javed conceived the idea and designed the experiments. K. Javed, X. M. Zhang, S. Parajuli, S. S. Ali, N. Ahmad, and M. Irfan were responsible for experiments, measurements and data analysis. X. F. Han, J. F, Feng, and S. A. Shah reviewed and commented on the paper. All authors discussed the results and commented on the manuscript.
9
Author Contribution Statement X. F. Han and K. Javed conceived the idea and designed the experiments. K. Javed, X. M. Zhang, S. Parajuli, S. S. Ali, N. Ahmad, and M. Irfan were responsible for experiments, measurements and data analysis. X. F. Han, J. F, Feng, and S. A. Shah reviewed and commented on the paper. All authors discussed the results and commented on the manuscript.
10
Highlights 1. Highly order NiMnGa alloy nanowires have been fabricated by simple and low-cost DC electrodeposition with different compositions. 2. With the increase in deposition potential there is an increase in Mn concentration and decrease in Ga contents. 3. Magnetic properties of NiMnGa nanowires can be modified by changing its composition. 4. A linear dependence of coercivity on temperature has been found for Ni2.8Mn0.2Ga1.0 sample.
11