粒子間交互作用對奈米錫自旋極化的增益效應

Enhanced spin-polarization by interparticle interaction

陳書偉(Shu-Wei Chen)

指導教授 ： 李文献

國立中央大學/理學院/物理學系/碩士(2007年)

摘要

使用熱蒸鍍法製作錫奈米微粒，以Sn060302表示。以SEM、AFM與X光繞射圖，定出微粒粒徑。從EDS與X光繞射圖分析，錫奈米微粒無明顯氧化物。
3.3nm的錫奈米微粒，Sn060302，觀察到自旋極化現象。本論文近一步壓合奈米微粒，產生交互作用，觀察到自旋極化有明顯的增益現象。在粒子間距在2nm時，飽和磁化強度有最大值。交互作用的系統複雜，以交換能、磁矩-磁矩交互作用為主要影響微粒的自旋極化。具有自旋極化的錫奈米微粒經壓合產生磁化強度增強，剩磁增大，類似於磁疇與交換能的鐵磁性現象。

關鍵字

自旋極化

並列摘要

We selected a gas-evaporation method to product Sn nanoparticles. The sample which was characterized using field emission scanning electron microscope, atomic force microscope observations, and x-ray diffraction measurements didn’t obviously constitute in tin oxides analyzed by energy dispersive spectrometer and x-ray diffraction measurements.
We demonstrate the spin polarization of Sn fine particles, Sn060302, with an average diameter of 3.3nm and furthermore, the enhanced magnetic property of Sn nanoparticles by reducing interparticle separation is studied as well as the maximum saturation magnetization with 2nm separation because of interparticle interaction. The interaction system is complicated. The major fact of enhanced magnetization is related to the exchange energy and dipole-dipole interaction. According to enhanced magnetization, enhanced remnant, alike domain, and exchange integral effect, the ferromagnetic spin polarization of Sn nanoparticles is observed.

並列關鍵字

spin-polarization

參考文獻

[1]M. Tischer, O. Hjortstam, D. Arvanitis, J. Hunter Dunn, F. May, K. Baberschke, J. Trygg, J. M. Wills, B. Johansson, and O. Eriksson, “Enhancement of Orbital Magnetism at Surfaces: Co on Cu(100),” Phys. Rev. Lett. 75 1602 (1995)

[2]T. Koide, H. Miyauchi, J. Okamoto, T. Shidara, A. Fujimori, H. Fukutani, K. Amemiya, H. Takeshita, S. Yuasa, T. Katayama, and Y. Suzuki, “Direct Determination of Interfacial Magnetic Moments with a Magnetic Phase Transitionin Co Nanoclusters on Au(111),” Phys. Rev. Lett. 87 257201 (2001)

[3]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)

[4]T. Shinohara and T. Sato, “Surface Ferromagnetism of Pd Fine Particles,” Phys. Rev. Lett. 91 197201 (2003)

[5]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)