| 摘要(英) |
Abstract
The double provskites A2BB’O6 have attracted lots of interest recently, Sr2FeMoO6 is one of them having great magnetoresistance performances ( high operating temperature and low applied field ). In this experiment, we discuss the influence of replacing the Sr atoms in Sr2FeMoO6 with Ca atoms and found that the structure of Sr2FeMoO6, space group I4/m, changes to P21/n when Ca took the place of Sr. An angle distortion was observed clearly, the angle of Fe-O-Mo changes from 180?( Sr2FeMoO6, I4/m ) to about 154?( Ca2FeMoO6, P21/n ).
Then we refine the magnetic structure by fitting the high flux neutron scattering patterns. The direct-exchange interaction of Fe-Mo become stronger because the bonding angle of Fe-O-Mo decreases, and it will balance with the super-exchange interaction of Fe-O-Mo; this makes the relative directions of Fe and Mo moments change from a canted anti-ferromagnetic arrangement to a noncolinear ferromagnetic arrangement. Finally, by measuring the magnetic susceptibility and the integrating intensity vs. temperature, we confirmed that there are two transition temperature in both samples, 165K ( Mo ) and 450K ( Fe ) in Sr2FeMoO6, 150K ( Mo ) and 380K ( Fe ) in Ca2FeMoO6. |
| 參考文獻 |
參考文獻
[1] 田民波 磁性材料，清华大学出版社 ( 2001 )
[2] 金重勳 磁性技術手冊，中華民國磁性技術協會 (2002 )
[3] 詹丁山 具穿隧磁電阻之有序結構金屬氧化物合成及其特性分
析，台灣大學化學所博士論文
[4] M. N. Baibich, J. M. Broto, A. Fert, F. Nguyen Van Dau, and F.
Petroff, Phys. Rev. Lett. 61, 2472. ( 1988 )
[5] R. von Helmolt, J. Wecker, B. Holzapfel, L. Schultz, and K. Samwer,
Phys. Rev. Lett. 71, 2331. ( 1993 )
[6] K. –I. Kobayashi, T. Kimura, H. Sawada, K. Terakura, & Y. Tokura,
Nature, 395, 677. ( 1998 )
[7] S. Jin, T. H. Tiefel, M. McCormack, R. A. Fashacht, R. Ramesh, L. H. Chen, Science, 264, 413. ( 1994 )
[8] Liu Ning, Sun Yang, Zhang Yu-Heng, Chinese Phys. Lett. 18, 957.
( 2001 )
[9] 許樹恩，吾泰伯 X光繞射原理與材料結構分析 中國材料科學
學會 ( 1996 )
[10] G. L. Squires, Introduction to The Theory of Thermal Neutron
Scattering, Cambridge University Press. ( 1978 )
[11]Ludwik Dobrzynski, Konrad Blinowski, Neutrons and Solid State
Physics, Ellis Horwood. ( 1994 )
[12]張廣容 鐠-鋇-銅-氧化物( PrBa2Cu3O7 )中摻入鋅或鉈時對鐠的
磁有序影響 中央大學碩士論文 ( 1993 )
[13]盧天惠 X光繞射與應用 滄海書局 ( 2002 )
[14]D. Sa´nchez, J. A. Alonso,* M. Garcý´a-Herna´ndez, M. J.
Martý´nez-Lope, and J. L. Martý´nez, Phys. Rev. B, 65, 104426
( 2002 )
[15]賴佳伶 零維鉛奈米粉粒超導磁穿透深度與粒徑關係探討 中
央大學碩士論文 ( 2003 )
[16]PPMS User’s Manual, Quantum Design. ( http://www.qdusa.com/ )
[17]E. Maxwell and Myron Strongin, Phys. Rev. Lett., 10, 212. ( 1963 )
[18]F. Brailsford, Physical Principles of Magnetism, D. Van Nostrand
Company Ltd London. ( 1966 ) |
[Endnote RIS 格式]
[相關文章]
[文章引用]
[完整記錄]
[館藏目錄]
[檢視]
plurk
funp
live
udn
HD
myshare
netvibes
friend
youpush
delicious
baidu
Google bookmarks
del.icio.us
hemidemi
facebook
twitter
google
reddit