Low-Temperature Magnetic Properties of Hematite Nanorods
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- 作者：Yimin Zhao ; Charles W. Dunnill ; Yanqiu Zhu ; Duncan H. Gregory ; Walter Kockenberger ; Yanhui Li ; Weibing Hu ; Iftikhar Ahmad ; David G. McCartney
- 刊名：Chemistry of Materials
- 出版年：2007
- 出版时间：February 20, 2007
- 年：2007
- 卷：19
- 期：4
- 页码：916 - 921
- 全文大小：329K
- 年卷期：v.19,no.4(February 20, 2007)
- ISSN：1520-5002
文摘
Low-temperature magnetic properties of hematite nanorods, prepared by both iron-water vapor reactions(sample 1) and hydrothermal methods (sample 2), were studied by superconducting quantum interferencedevice (SQUID) magnetometry. The Morin transition temperature was found to be 122 K in hematitenanorod sample 1, and an unexpected phenomenon was found under an applied field of 10 Oe. Thesenanorods (sample 1) show an abrupt decrease of the magnetic susceptibility at ca. 122 K, contrary to theabrupt increase normally attributed to the Morin transition in bulk hematite. The origin of this phenomenoncan be traced to the probable coherence of the one-dimensional shape anisotropy with the magnetocrystalline anisotropy. In contrast, no obvious Morin transition was found in hematite nanorod sample 2.