Abstract
Films of Fe/Sm–Co magnetic nanocomposites were successfully synthesized by means of spin-assisted layer-by-layer deposition. The Fe-layer thickness was varied by controlling the spinning speeds and its effect on the structural and magnetic properties of Fe(t Fe)/Sm–Co(250 nm) films with t Fe = 15 and 30 nm was investigated. Energy-dispersive X-ray analysis confirmed the presence of Sm, Co, and Fe in the samples, which suggests complete decomposition of the precursor films after reductive annealing. Atomic force microscopy examinations revealed the formation of spherical grains in the Sm–Co layer and the estimated mean grain size values were slightly lower for t Fe = 15 nm (34 ± 6.3 nm); when compared to those obtained for t Fe = 30 nm (48 ± 8.4 nm). Irrespective of t Fe, X-ray diffraction studies showed the crystallization of Sm(Co,Fe)7-phase in both the films after their reduction at 500 °C and this metastable phase was transformed into SmCo5 and Sm2Co17-phases on annealing at 600 °C. The occurrence of these two phases was further confirmed by thermomagnetic measurements in terms of distinguished magnetic transitions at ~723 and ~905 °C, respectively. Room temperature magnetic measurements by superconducting quantum interference device, demonstrated the influence of t Fe on the hard magnetic behavior of the films. A good combination of high coercivity (6.2 kOe), high remanence ratio (0.73), and magnetization (3.35 memu) was obtained with t Fe = 15 nm. The results of our study suggest that the simple spin coating process can be applied efficiently to produce thick magnetic films of Fe/Sm–Co for possible applications in magnetic micro-electro-mechanical system devices.
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References
Buschow KHJ (1991) New developments in hard magnetic materials. Rep Prog Phys 54:1123–1213
Carbucicchio M, Prezioso M, Rateo M, Bennett S, Berry FJ (2005) Microstructural and magnetic properties of SmCo5-based films and multilayers. AIP Conf Proc 765:196–199
Chu S, Majetich SA, Huang N, Fingers RT (2003) Synthesis and magnetic behavior of SmCo5−x Fe x nanocomposite magnets. J Appl Phys 93:8146–8148
Coey JMD (1996) Industrial applications of permanent magnetism. Phys Scripta 66:60–66
Cui BZ, Huang M-Q, Liu S (2003) Magnetic properties of SmCo7/Co and Sm(Co, Fe)7/α-(Fe, Co) nanocomposite magnets prepared by magnetic annealing. IEEE Trans Magn 39:2866–2868
Hadjipanayis GC (1999) Nanophase hard magnets. J Magn Magn Mater 200:373–391
Hou Y, Sun S, Rong C, Liu JP (2007) SmCo5/Fe nanocomposites synthesized from reductive annealing of oxide nanoparticles. Appl Phys Lett 91:153117
Kneller EF, Hawig R (1991) The exchange-spring magnet: a new material principle for permanent magnets. IEEE Trans Magn 27:3588–3600
Liu T, Li W, Li WM, Feng WC, Guo YQ (2007) Crystal structure and magnetic properties of SmCo7−x Ag x . J Magn Magn Mater 310:e632–e634
Neu V, Häfner K, Patra AK, Schultz L (2006) Fully epitaxial, exchange coupled SmCo5/Fe/SmCo5 trilayers. J Phys D 39:5116–5120
Park C-D, Magana D, Stiegman AE (2007) High-quality Fe and α-Fe2O3 magnetic thin films from an epoxide-catalyzed sol–gel process. Chem Mater 19:677–683
Pechini MP (1967) Method of preparing lead and alkaline earth titanates and niobates and coating method using the same to form a capacitor. US Patent 3330697
Pop V, Isnard O, Chicinas I, Givord D (2007) Magnetic and structural properties of SmCo5/α-Fe nanocomposites. J Magn Magn Mater 310:2489–2490
Saravanan P, Srinivasa Rao K, Mishra D, Perumal A, Chandrasekaran V (2010) One-step synthesis of Sm–Co spherical granules via superhydride reduction. Adv Sci Lett 3:49–52
Saravanan P, Venkata Ramana G, Srinivasa Rao K, Sreedhar B, Perumal A (2011) Thin magnetic films of Sm–Co nanocrystallites exploiting spin coating deposition. Thin Solid Films 519:6290–6296
Saravanan P, Kamat SV, Sreedhar B (2012) Thin magnetic films of Sm–Co nanocrystallites exploiting spin coating deposition. J Magn Magn Mater 324:1201–1204
Saravanan P, Hsu J-H, Gayen A, Singh AK, Perumal A, Reddy GLN, Kumar S, Kamat SV (2013) Effect of Fe layer thickness and Fe/Co intermixing on the magnetic properties of Sm–Co/Fe bilayer exchange-spring magnets. J Phys D 46:155002
Schrefl T, Fidler J, Kronmüller H (1994) Remanence and coercivity in isotropic permanent magnets. Phys Rev B 49:6100–6110
Schrefl T, Forster H, Dittrich R, Suess D, Scholz W, Fidler J (2003) Reversible magnetization processes and energy density product in Sm–CoFe and Sm–Co/Co bilayers. J Appl Phys 93:6489–6491
Skomski R, Coey JMD (1993) Giant energy product in two-phase magnets. Phys Rev B 48:15812–15816
Su HL, Tang NJ, Nie B, Wang RL, Lu M, Zhang SY, Lv LY, Du YW (2007) Magnetically hard face-centered-tetragonal FePt film prepared by sol–gel spin coating. Thin Solid Films 515:7066–7069
Sui Y, Yue L, Skomski R, Li XZ, Zhou J, Sellmyer DJ (2003) CoPt hard magnetic nanoparticle films synthesized by high temperature chemical reduction. J Appl Phys 93:7571–7573
Takei S, Morisako A, Matsumoto M (2000) Effect of underlayer thickness on magnetic properties of SmCo film. J Appl Phys 87:6968–6970
Velu EMT, Lambeth DN, Thornton JT, Russell PE (1994) AFM structure and media noise of SmCo/Cr thin films and hard disks. J Appl Phys 75:6132–6134
Wang H, Zhou M, Yang F, Wang J, Jiang Y, Wang H, Li Q (2009) Monolayer assembly and fixation of FePt nanoparticles: microstructure and magnetic properties. Chem Mater 21:404–409
Zeng H, Li J, Liu JP, Wang ZL, Sun S (2002) Exchange-coupled nanocomposite magnets by nanoparticle self-assembly. Nature 420:395–398
Zhang J, Takahashi YK, Gopalan R, Hono L (2005) Sm(Co, Cu)5/Fe exchange spring multilayer films with high energy product. Appl Phys Lett 86:122509
Zhang J, Song J-Z, Zhang Y, Wang F, Chen B-C, Shen B-G, Sun J-R (2011) Magnetic reversal and temperature dependence of magnetic properties in Sm–(Co, Cu)/Fe exchange spring multilayer film. IEEE Trans Magn 47:2792–2795
Acknowledgments
The financial support for this study was extended by Defence Research and Development Organization (DRDO), Government of India. The keen interest shown by the Director, DMRL in this work is gratefully acknowledged. One of the authors PS thanks National Science Council of Taiwan for providing postdoctoral fellowship under contract No. NSC-99-2112-M-002-020-MY3.
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Saravanan, P., Hsu, JH. & Kamat, S.V. Granular films of Fe/Sm–Co magnetic nanocomposites through spin-assisted layer-by-layer deposition. J Nanopart Res 15, 2117 (2013). https://doi.org/10.1007/s11051-013-2117-0
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DOI: https://doi.org/10.1007/s11051-013-2117-0