本實驗研究由壓電材料與磁致伸縮材料組合而成的磁電複合材料，有別於傳統的法拉第之電流電磁感應，磁電複合材料的磁電轉換效應是籍由電壓驅動，可以避免電流造成的熱效應，在元件應用上具重要意義。本實驗中複合材料的兩相組員分別是BiFeO3和CoFe2O4，以及BiFeO3和Co0.5Zn0.5Fe2O4。初始先單獨濺鍍CoFe2O4、Co0.5Zn0.5Fe2O4、BiFeO3於Si基板上，探討兩相可匹配的濺鍍參數，找出適當的鍍膜條件，後續藉由雙靶共濺鍍的方式，將兩相沉積在以LaNiO3作為底電極的 Si 基板上，並探討在雙靶共濺鍍的環境下，改變各項成長參數，如氣氛、鍍率、基板溫度等，對形成純相BiFeO3、CoFe2O4以及Co0.5Zn0.5Fe2O4之影響，以及CoFe2O4摻雜Zn對複合材料薄膜成長條件及磁電相關物理性質的改變。

關鍵字：磁控濺鍍法、複合材料、BiFeO3、CoxZn1-xFe2O4
 

Magnetoelectric (ME) composites are composed of a piezoelectric phase and a magnetostrictive phase. Different from Faraday’s law, the ME effect in such a composite is driven by voltage, which can avoid the thermal effect caused by eletric current. In this experiment, ferroelectric BiFeO3 (BFO) and ferrimagnetic CoxZn1-xFe2O4 (x= 1 and 0.5, CZFO) were chosen as the components for the composite, which was deposited on the LaNiO3 (LNO) buffered Si substrate by co-sputtering from two individual targets of BFO and CZFO, respectively. The LNO layer on Si was used as the bottom electrode for the measurement of ME voltage vertically to the film. This extended abstract discusses the effects of changing various sputtering parameters, such as chamber pressure, oxygen partial pressure (PO2), deposition rate, substrate temperature, etc., on the formation of pure phases of BFO and CZFO, as well as the variations of physical properties. The best samples were obtained with the sputter powers of 100 W (BFO) and 200 W (CZFO), substrate temperature of 650 oC, PO2 of 10 mTorr, deposition rate of 3 nm/min (CZFO, x= 1) and 4.6 nm/min (CZFO, x= 0.5). The highest magnetoelectric voltage coefficients achived were 455 mVcm-1Oe-1, which were measured at the frequency of 1 kHz with the BFO-CZFO (x= 1) samples.
Key words﹕Co-sputtering, composites, BiFeO3, CoxZn1-xFe2O4

[1] Z.Chu, M.Pourhosseiniasl, and S.Dong, “Review of multi-layered magnetoelectric composite materials and devices applications,” J. Phys. D. Appl. Phys., vol. 51, no. 24, 2018.
[2] N. M.Aimon, D. H.Kim, X.Sun, and C. A.Ross, “Multiferroic Behavior of Templated BiFeO3 − CoFe2O4 Self-Assembled Nanocomposites,” ACS applied materials & interface, pp. 3–8, 2015.
[3] R. A.Islam, Y.Ni, A. G.Khachaturyan, and S.Priya, “Giant magnetoelectric effect in sintered multilayered composite structures,” J. Appl. Phys., vol. 104, no. 4, 2008.
[4] R. A.Islam, C. B.Rong, J. P.Liu, and S.Priya, “Effect of gradient composite structure in cofired bilayer composites of Pb(Zr0.56Ti0.44)O3-Ni0.6Zn0.2Cu0.2Fe2O4 system on magnetoelectric coefficient,” J. Mater. Sci., vol. 43, no. 18, pp. 6337–6343, 2008.
[5] E.Lage et al., “Exchange biasing of magnetoelectric composites,” Nat. Mater., vol. 11, no. 6, pp. 523–529, 2012.
[6] K. H.Lam, C. Y.Lo, and H. L. W.Chan, “Frequency response of magnetoelectric 1-3-type composites,” J. Appl. Phys., vol. 107, no. 9, 2010.
[7] A.McDannald, M.Staruch, G.Sreenivasulu, C.Cantoni, G.Srinivasan, and M.Jain, “Magnetoelectric coupling in solution derived 3-0 type PbZr 0.52Ti0.48O3:xCoFe2O4 nanocomposite films,” Appl. Phys. Lett., vol. 102, no. 12, pp. 0–4, 2013.
[8] Palneedi, Haribabu, et al. "Status and perspectives of multiferroic magnetoelectric composite materials and applications." Actuators. Vol. 5. No. 1. Multidisciplinary Digital Publishing Institute, 2016.
[9] A.Datar, B.Ray, S.Datar, and V.Mathe, “Magnetic force microscopic analysis and the magnetoelectric sensor of PLZT – Spinel ferrite composite films,” J. Magn. Magn. Mater., vol. 489, no. May, p. 165373, 2019.
[10] Y.Bai, J.Chen, S.Zhao, and Q.Lu, “Magneto-dielectric and magnetoelectric anisotropies of CoFe2O4/Bi5Ti3FeO15 bilayer composite heterostructural films,” RSC Adv., vol. 6, no. 57, pp. 52353–52359, 2016.
[11] K.Chand Verma, S. K.Tripathi, and R. K.Kotnala, “Magneto-electric/dielectric and fluorescence effects in multiferroic xBaTiO3-(1 - x)ZnFe2O4 nanostructures,” RSC Adv., vol. 4, no. 104, pp. 60234–60242, 2014.
[12] T. C.Kim et al., “Effect of sputtering conditions on the structure and magnetic properties of self-assembled BiFeO3-CoFe2O4 nanocomposite thin films,” J. Magn. Magn. Mater., vol. 471, pp. 116–123, 2019.
[13] D. G. R.William D. Callister, Materials Science & Engineering 9/E. Wiley, 2014.
[14] K. h. j.Buschow and F. R. drBoer, Physics of magnetism and magnetic materials s, Kluwer Academic/Plenum Publisher, New York, 2003.
[15] N. A.Spaldin, Magnetic materials: fundamentals and applications. Cambridge University Press, 2010.
[16] W.Heisenberg, “Zur theorie des ferromagnetismus,” Zeitschrift fu ̈r Phys., no. 49, pp. 619–636, 1928.
[17] B. D. Cullity, C. D. Graham, Introduction to magnetic materials, John Wiley & Sons, 2011.
[18] 近角聰信，張煦，李學養，磁性物理學，臺北: 聯經出版事業公司， 1982。
[19] P.Curie, “Sur la symétrie dans les phénomènes physiques, symétrie d’un champ électrique et d’un champ magnétique,” J. Phys. théorique appliquée, vol. 3, no. 1, pp. 393–415, 1894.
[20] D. N.Astrov, “The magnetoelectric effect in antiferromagnetics,” Sov. Phys. - JETP, vol. 11, no. 3, p. 708, 1960.
[21] G. T.Rado and V. J.Folen, “Observation of the Magnetically Induced Magnetoelectric,” Phys. Rev. Lett., vol. 7, no. 8, pp. 310–311, 1961.
[22] M.Fiebig, “Revival of the magnetoelectric effect,” J. Phys. D. Appl. Phys., vol. 38, no. 8, 2005.
[23] R. P. Santoro, R. E. Newnham, Survey of magnetoelectric materials, Massachysettsinst of Tech Cambridge Lab for Insulation Research, 1966.
[24] E.Ascher and A. G. M.Janner, “Upper bounds on the magneto-electric susceptibility,” Phys. Lett. A, vol. 29, no. 6, p. 295, 1969.
[25] V.Wadhawan, Introduction to Ferroic Materials, 1st Editio. London, 2000.
[26] N. A.Hill, “Why are there so few magnetic ferroelectrics?,” J. Phys. Chem. B, vol. 104, no. 29, pp. 6694–6709, 2000.
[27] G. A. Smolenskii, I. E. Chupis, “Ferroelectromagnets”, Soviet Physics
Uspekhi, 25, 475, 1982.
[28] N.Ortega, A.Kumar, J. F.Scott, and R. S.Katiyar, “Multifunctional magnetoelectric materials for device applications,” J. Phys. Condens. Matter, vol. 27, no. 50, 2015.
[29] E.Ascher, H.Rieder, H.Schmid, and H.Stössel, “Some Properties of Ferromagnetoelectric Nickel‐Iodine Boracite, Ni3B7O13I,” J. Appl. Phys., vol. 37, no. 3, pp. 1404–1405, Mar.1966.
[30] E. F. Bertaut, M. Mercier, Structure magnetique de MnYO3, Physics Letters, 5, 27-29, 1963.
[31] N.Ikeda et al., “Ferroelectricity from iron valence ordering in the charge-frustrated system LuFe2O4,” Nature, vol. 436, no. 7054, pp. 1136–1138, 2005.
[32] B. D. H.Tellegen, “The Gyrator.” Philips Res. Rep, 3, pp. 81–101, 1948.
[33] J.vanSuchtelen, “Product properties: A new Application of Composite Materials,” Philips Res. Rep., vol. 27, pp. 28–37, 1972.
[34] A. M. J. G.VanRun, D. R.Terrell, and J. H.Scholing, “An in situ grown eutectic magnetoelectric composite material,” J. Mater. Sci., vol. 9, no. 10, pp. 1710–1714, Oct.1974.
[35] A. M. J. G.VanRun, D. R.Terrell, and J. H.Scholing, “An in situ grown eutectic magnetoelectric composite material - Part 2 Physical properties,” J. Mater. Sci., vol. 9, no. 10, pp. 1710–1714, 1974,.
[36] C. W.Nan, M. I.Bichurin, S.Dong, D.Viehland, and G.Srinivasan, “Multiferroic magnetoelectric composites: Historical perspective, status, and future directions,” J. Appl. Phys., vol. 103, no. 3, 2008.
[37] C. W.Nan, N.Cai, L.Liu, J.Zhai, Y.Ye, and Y.Lin, “Coupled magnetic-electric properties and critical behavior in multiferroic particulate composites,” J. Appl. Phys., vol. 94, no. 9, pp. 5930–5936, 2003.
[38] E. G.Turitsyna and S.Webb, “Simple design of FBG-based VSB filters for ultra-dense WDM transmission ELECTRONICS LETTERS 20th January 2005,” Electron. Lett., vol. 41, no. 2, pp. 40–41, 2005.
[39] Y.Zhang, Z.Li, C.Deng, J.Ma, Y.Lin, and C. W.Nan, “Demonstration of magnetoelectric read head of multiferroic heterostructures,” Appl. Phys. Lett., vol. 92, no. 15, 2008.
[40] C.Fang et al., “Significant reduction of equivalent magnetic noise by in-plane series connection in magnetoelectric Metglas/Mn-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 laminate composites,” J. Phys. D. Appl. Phys., vol. 48, no. 46, 2015.
[41] A. M.Kadomtseva, Y. F.Popov, A. P.Pyatakov, G. P.Vorob’Ev, A. K.Zvezdin, and D.Viehland, “Phase transitions in multiferroic BiFeO3 crystals, thin-layers, and ceramics: Enduring potential for a single phase, room-temperature magnetoelectric ‘holy grail,’” Phase Transitions, vol. 79, no. 12, pp. 1019–1042, 2006.
[42] C.Ederer and N. A.Spaldin, “Weak ferromagnetism and magnetoelectric coupling in bismuth ferrite,” Phys. Rev. B - Condens. Matter Mater. Phys., vol. 71, no. 6, pp. 1–4, 2005.
[43] R.Valenzuela, Magnetic ceramics, vol. 4. Cambridge university press, 2005.
[44] M.Akram and M.Anis-Ur-Rehman, “Dependence of site occupancy and structural and electrical properties on successive replacement of Co by Zn in CoFe2O4,” J. Electron. Mater., vol. 43, no. 2, pp. 485–492, 2014.
[45] C. M. Srivastava, G. Srinivasan, and N. G. Nanadikar, “Exchange constants in spinel ferrites,” Physical Review B, vol. 19, no. 1, pp. 499-508, 1979.
[46] J.Smit andH. P. J.Wijn, Ferrites : physical properties of ferrimagnetic oxides in relation to their technical applications. Eindhoven: N.V. Philips Gloeilampenfabrieken, 1959.
[47] A.Srinivas and T.Bhimasankaram, “An experimental setup for dynamic measurement of magnetoelectric effect,” Bulletin of Materials Science, vol. 21, no. 3, pp. 251–255, 1998.
[48] S. S.Kumbhar, M. A.Mahadik, V. S.Mohite, Y. M.Hunge, K. Y.Rajpure, and C. H.Bhosale, “Effect of Ni content on the structural, morphological and magnetic properties of spray deposited Ni-Zn ferrite thin films,” Mater. Res. Bull., vol. 67, pp. 47–54, 2015.
[49] M.A.Gabal, et al. , “PSynthesis, characterization and electromagnetic properties of Zn-substituted CoFe2O4 via sucrose assisted combustion route,” Journal of Magnetism and Magnetic Materials, vol. 426, pp. 670-679, 2017.