以中子繞射與磁性量測探討奈米金顆粒表面與內核之自發磁矩

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姓名

李祈延(Chi-Yen Li) 查詢紙本館藏

畢業系所

物理學系

論文名稱

以中子繞射與磁性量測探討奈米金顆粒表面與內核之自發磁矩
(Intrinsic surface and core magnetic moments in Au nanoparticles - neutron diffraction and magnetization studies)

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摘要(中)

我們以氣化冷凝法製備一系列粒徑各異、且表面無附有其他化學分子之奈米金顆粒粉末。利用X-射線繞射譜圖分析粒徑，判定所研製不同顆粒大小之粉末樣品的平均粒徑為3奈米至8.4奈米。從磁化強度量測的實驗結果，觀察到奈米金顆粒的自發磁性，以及當量子侷域效應顯現後由磁場所引發之感應磁矩。顆粒磁矩隨著溫度升高而增大，此可由自旋波模型(Spin-wave model)來解釋熱磁激發之現象。而量子奈米顆粒自發磁性的內涵來源，與顆粒表面電子轉移(charge transfer)有關。
從中子粉末繞射實驗的結果，可探測奈米粉體的微觀磁性。由5 K與300 K的磁繞射峰計算出4.3奈米金顆粒的磁矩大小為0.14個波爾磁子，指向[111]晶面方向。且除了表面金原子外，內層金原子對自發磁矩也有貢獻。我們並發現不同粒徑之奈米金顆粒，其各異的s-d 混成軌域之能量，直接反應了自發磁性的強弱。
利用壓合模具進一步縮短顆粒間的聚合密度，發現顆粒間交互作用的增強，會造成顆粒表面導電電子密度的下降，進而使表面金原子與內層金原子間電子重新分布(charge redistribution)，同時影響顆粒磁矩的大小。

摘要(英)

Five sets of capping-free bare Au nanoparticle samples are fabricated by gas condensation method. X-ray diffraction, energy dispersive x-ray spectroscopy, and transmission electron microscopy are used to characterize the samples. We determine the mean particle diameter by fitting the diffraction peaks of finite-sized nanoparticles, assuming the same size distribution obtained from the TEM images, ranging from 3 to 8.4 nm.
Neutron powder diffraction detects ferromagnetic moment of μz = 0.14 μB that points in the [111] direction. The magnetization of 3 nm Au nanoparticle assembly reveals a Langevin profile and a Brillouin profile which can be understood as the condensation of quantum-confined electrons into the Zeeman spin-polarized states. The M(Ha) characteristic signifies the existence of spin correlations in the Au nanoparticle assemblies. Spin arrangements in loosely packed 3 nm Au particles assembly are found to be ferrimagnetic-like, where the core and surface moments point in opposite directions. The magnetic transition in interacting nanoparticles will be clearly seen. Reductions in magnetization and density of conduction electrons upon closing up the interparticle separation are also observed.
Size dependence of magnetic entropy change at Ha ~ 10 kOe obtained from the isothermal M(Ha) curves, indicating the interplay between surface and core magnetic moment. The entropy change increases for 3 nm Au particle assembly below 50 K, whereas the weak surface contribution is observed as particle diameter increasing to 8.4 nm

關鍵字(中)

★ 中子散射
★ 磁性
★ 奈米顆粒

關鍵字(英)

★ Neutron scattering
★ Magnetism
★ Nanoparticle

論文目次

Chinese abstract.........................................i
English abstract........................................ii
Acknowledgments........................................iii
Contents................................................iv
List of figures.........................................vi
List of tables..........................................ix
1 Introduction and motivation 1
2 Fabrication and characterization of nanoparticles 6
2.1 Sample fabrication..................................6
2.2 Sample characterization.............................8
3 Effects from size distribution 15
3.1 Zeeman magnetization and superpaaramagnetism.......15
3.2 Magnetic moment distribution.......................20
3.3 Localized magnetic moment..........................28
4 Development of magnetic moment and effects of
interparticle interactions 31
4.1 Surface and core magnetic moments..................31
4.2 Hysteresis and spin reorientation model............42
4.3 Packing nanoparticle assembly......................48
4.4 Effects of magnetostatic interparticle interactions52
5 Size effects 57
5.1 Size dependence of magnetization curves............57
5.2 Surface contribution to the magnetic properties....63
5.3 Magnetic entropy...................................69
6 Intrinsic magnetic moment 80
6.1 Neutron diffraction techniques.....................80
6.2 Instrumentation....................................83
6.3 Theory of neutron diffraction......................85
6.4 Magnetic ordering and intrinsic magnetic moment....87
7 Conclusions 93
Bibliography 95

參考文獻

[1] J. Z. Sun, Current-driven magnetic swiching in magnetic trilayer junctions, Journal of magnetism and magnetic materials 202, 157 (1999).
[2] V. F. Puntes, P. Gorostiza, D. M. Aruguete, N. G. Bastus, and A. P. Alivisatos, Collective behaviour in two-dimensional cobalt nanoparticle assemblies onserved by magnetic force microscopy, Nature materials 3, 263 (2004).
[3] K. Chatterjee, S. Banerjee, and D. Chakravorty, Plasmon resonance shifts in oxide-coated silver nanoparticles, Phy. Rev. B 66, 085421 (2002).
[4] A. M. Tishin and Y. I. Spichkin, The magnetocaloric effect and its applications (IOP, 2003).
[5] E. Warburg, Magnetische untersuchungen, Ann. Phys. 13, 141 (1881).
[6] P. Debye, Einige bemerkungen zur magnetisieurung bei taefer temperature, Ann. Phys. 81, 1154 (1926).
[7] W. F. Giauque, A thermodynamic treatment of certain magnetic effects. A proposed method to produce temperatures considerably below 1˚ absolute, J. Am. Chem. Soc. 49, 1864 (1927).
[8] B. G. Shen, J. R. Sun, F. X. Hu, H. W. Zhang, and Z. H. Cheng, Recent progress in exporing magnetocaloric materials, Adv. Mater. 21, 4545 (2009).
[9] S. Kim, S. Ghirlanda, C. Adams, B. Bethala, S. N. Sambandam, and S. Bhansali, Int. J. Energy Res. 31, 717 (2007).
[10] Allan H. Morrish, The physical principles of magnetism (John Wiley & Sons, New York, 1965).
[11] H. Hori, T. Teranishi, Y. Nakae, Y. Seino, M. Miyake, S. Yamada, Anomalous magnetic polarization effect of Pd and Au nano-particles, Phys. Lett. A 263, 406 (1999).
[12] H. Hori, Y. Yamamoto, T. Iwamoto, T. Miura, T. Teranishi, and M. Miyake, Diameter dependence of ferromagnetic spin moment in Au nanocrystals, Phys. Rev. B 69, 174411 (2004).
[13] Y. Yamamoto, T. Miura, M. Suzuki, N. Kawamura, H. Miyagawa, T. Nakamura, K. Kobayashi, T. Teranishi, and H. Hori, Direct Observation of ferromagnetic spin polarization in gold nanoparticles, Phys. Rev. Lett. 93, 116801 (2004).
[14] P. Crespo, R. Litr?n, T.C. Rojas, M. Multigner, J.M. de la Fuente, J. C. S?nchez-L?pez, M. A. Garc?a, A. Hernando, S. Penad?s, and A. Fern?ndez, Permanent magnetism, magnetic Anisotropy, and hysteresis of thiol-capped gold nanoparticles, Phys. Rev. Lett. 93, 087204 (2004).
[15] Chi-Yen Li, Chun-Ming Wu, Sunil K. Karna, Chin-Wei Wang, Daniel Hsu, Chih-Jen Wang, and Wen-Hsien Li, Intrinsic magnetic moments of gold nanoparticles, Phys. Rev. B 83, 174446 (2011).
[16] C. L?pez-Cartes, T. C. Rojas, R. Litr?n, D. Mart?nez-Mart?nez, J. M. de la Fuente, S. Penad?s, and A. Fern?ndez, Gold nanoparticles with different capping systems: An electronic and structural XAS analysis, J. Phys. Chem. B 109, 8761 (2005).
[17] Peng Zhang and T. K. Sham, X-Ray studies of the structure and electronic behavior of alkanethiolate-capped gold nanoparticles: The interplay of size and surface Effects, Phys. Rev. Lett. 90, 245502 (2003).
[18] Chun-Ming Wu, Chi-Yen Li, Yen-Ting Kuo, Chin-Wei Wang, Sheng-Yun Wu, and Wen-Hsien Li, Quantum spins in Mackay icosahedral gold nanoparticles, J. Nanopart. Res. 12, 177 (2010).
[19] M. Pereiro and D. Baldomir, Determination of the lowest-energy structure of Ag8 from first-principles calculations, Phys. Rev. A 72, 045201 (2005).
[20] C. M. Chang and M. Y. Chou, Alternative low-symmetry structure for 13-atom metal clusters, Phys. Rev. Lett. 93, 133401 (2004).
[21] H. J. Juretschke, Exchange potential in the surface region of a free-electron metal. Phys. Rev. 92, 1140 (1953).
[22] M. K. Harbola, V. Sahni, Structure of the Fermi hole at surfaces, Phys. Rev. B 37, 745 (1988).
[23] Kenji Koga, Tamio Ikeshoji, and Ko-ichi Sugawara, Size- and temperature-dependent structural transitions in gold nanoparticles, Phys. Rev. Lett. 92, 115507 (2004).
[24] A. C. Larson and R. B. Von Dreele, General Structure Analysis System (GSAS), Los Alamos National Laboratory Report LAUR 86-748 (2004).
[25] H. M. Rietveld, J. Appl. Cryst. 2, 65 (1969).
[26] Neil W. Aschcroft and N. David Mermin, Solid State Physics (Thomson Learning, 1976), p. 644.
[27] Charles Kittel, Introduction to Solid State Physics, 7th edition (John Wiley & Sons, New York, 1996).
[28] Nicola A. Spaldin, Magnetic Materials: Fundamentals and Device Applications (Cambridge University Press, New York, 2003).
[29] Wen-Hsien Li and Chun-Ming Wu, Reply to “Comment on ‘Coexistence of ferromagnetism and superconductivity in Sn nanoparticles’ ”, Phys. Rev. B 82, 016504 (2010).
[30] D. Craik, Magnetism: Principles and Applications (John Wiley & Sons, New York, 1995), p. 99
[31] Steen M?rup and Britt. Rosendahl Hansen, Uniform magnetic excitations in nanoparticles, Phys. Rev. B 72, 024418 (2005).
[32] P. V. Hendriksen, S. Linderoth, and P.-A. Lindg?rd, Finite-size modifications of the magnetic properties of clusters, Phys. Rev. B 48, 7259 (1993).
[33] K. Mandal, Subarna Mitra, and P. Anil Kumar, Deviation from Bloch T3/2 law in ferrite nanoparticles, Europhys. Lett. 75, 618 (2006).
[34] V. Senz, R. R?hlsberger, J Bansmann, O. Leupold, and K-H Meiwes-Broer, Temperature dependence of the magnetization in Fe islands on W(110): evidence for spin-wave quantization, New Journal of Physics 5, 47.1 (2003).
[35] E. Della Torre, L. H. Bennett, and R. E. Watson, Extension of the Bloch T3/2 Law to Magnetic Nanostructures: Bose-Einstein Condensation, Phys. Rev. Lett. 94,147210 (2005).
[36] C. Caizer, Magnetic behavior of Mn0.6Fe0.4Fe2O4 nanoparticles in ferrofluid at low tempertures, Journal of Magnetism and Magnetic Materials 251, 304 (2002).
[37] R. Aquino, J. Depeyrot, M. H Sousa, F. A. Touriho, E. Dubois, and R. Perzynski, Magnetization temperature dependence and freezing of surface spins in magetic fluids based on ferrite nanoparticles, Phys. Rev B 72,184435 (2005).
[38] T. N. Shendruk, R. D. Desautels, B. W. Southern, and J. van Lierop, The effect of surface spin disorder on the magnetism of γ-Fe2O3 nanoparticle dispersions, Nanotechnology 18, 455704 (2007).
[39] X.-H. Wei, R. Skomski, Z.-G. Sun, and D. J. Sellmyer, Proteresis in Co:CoO core-shell nanoclusters, Journal of Applied Physics 103, 07D514 (2008).
[40] Yue-Lin Huang, Kai Chih Chen, Sheng Yun Wu, Cheng-I Lin, and Su-Fan Yeh, Size-effect induced short-range magnetic ordering in germanium nanostructures, Journal of Nanoscience and Nanotechnology 10, 4629 (2010).
[41] Y. Z. Wu, G. S. Dong, and X. F. Jin, Negative magnetic remanence in Co/Mn/Co grown on GaAs(001), Phys. Rev. B 64, 214406 (2001).
[42] Jos S. Garitaonandia, Maite Insausti, Eider Goikolea, Motohiro Suzuki, John D. Cashion, Naomi Kawamura, Hitoshi Ohsawa, Izaskun Gil de Muro, Kiyonori Suzuki, Fernando Plazaola, and Teofilo Rojo, Chemically Induced Permanent Magnetism in Au, Ag, and Cu Nanoparticles: Localization of the Magnetism by Element Selective Techniques, Nano Lett. 8, 661 (2008).
[43] Wen-Hsien Li, Chun-Ming Wu, Chin-Wei Wang, Chi-Yen Li, and Chien-Kang Hsu, Formation of superconductivity through interparticle interactions in ferrimagnetic-like Sn nanoparticle assemblies, J. Nanopart. Res. 14, 764 (2012).
[44] N. W. Ashcroft and N. D. Mermin, Solid State Physics (Saunders College, Philadelphia, 1976).
[45] R. H. Kodama, A. E. Berkowitz, E. J. McNiff, Jr., and S. Foner, Surface spin disorder in NiFe2O4 nanoparticles, Phys. Rev. Lett. 77, 394 (1996).
[46] E. De Biasi, C. A. Ramos, R. D. Zysler, and H. Romero, Large surface magnetic contribution in amorphous ferromagnetic nanoparticles, Phys. Rev. B 65, 144416 (2002).
[47] R. J. Magyar, V. Mujica, M. Marquez, and C. Gonzalez, Density-functional study of magnetism in bare Au nanoclusters: Evidence of permanent size-dependent spin polarization without geometry relaxation, Phys. Rev. B 75, 144421 (2007).
[48] K. L. Krycka, R. A. Booth, C. R. Hogg, Y. Ijiri, J. A. Borchers, W. C. Chen, S. M. Watson, M. Laver, T. R. Gentile, L. R. Dedon, S. Harris, J. J. Rhyne, and S. A. Majetich, Core-shell magnetic morphology of structurally uniform magnetic nanoparticles, Phys. Rev. Lett. 104, 207203 (2010).
[49] Ralph Skomski, Simple models of magnetism (Oxford University Press, New York, 2008).
[50] R. Skomski, Ch. Binek, S. Michalski, T. Mukherjee, A. Enders, and D. J. Sellmyer, Entropy localization in magnetic compounds and thin-film nanostructures, J. Appl. Phys. 107, 09A922 (2010).
[51] T. Mukherjee, S. Michalski, R. Skomski, D. J. Sellmyer, Ch. Binek, Overcoming the spin-multiplicity limit of entropy by means of lattice degrees of freedom: A minimal model, Phys. Rev. B 83, 214413 (2011).
[52] Kerson Huang, Statistical mechanics, 2nd edition (John Wiley & Sons, New York, 1987).
[53] W.-H. Li, S. Y. Wu, C. C. Yang, S. K. Lai, K. C. Lee, H. L. Huang, and H. D. Yang, Thermal Contraction of Au Nanoparticles, Phys. Rev. Lett. 89, 135504 (2002).
[54] Ralph Skomki, Christian Binek, T. Mukherjee, S. Sahoo, and D. J. Sellmyer, Temperature- and field-induced entropy changes in nanomagnets, J. Appl. Phys. 103, 07B329 (2008).
[55] Erich H. Kisi, Chistopher J. Howard, Applications of neutron powder diffraction (Oxford University Press, USA, 2008)
[56] G. E. Bacon, Neutron diffraction, 3rd edition (Oxford University Press, Oxford, 1975).
[57] S. Y. Wu, Neutron scattering investigations of the hole-doped CMR maganates (Nd1-xCax)MnO3 and (La2-2xSr1+2x)Mn2O7 (Ph.D. thesis, National Central University, Taiwan, 1999).
[58] ANSTO website,
http://www.ansto.gov.au/research/bragg_institute/facilities/instruments
[59] A. J. Studer, M. E. Hagen, T. J. Noakes, Wombat: The high-intensity powder diffractometer at the OPAL reactor, Physica B 385-386, 1013 (2006).

指導教授

李文獻(Wen-Hsien Li)

審核日期

2012-8-30

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