Crystal Structure, Magnetic and Magnetotransport Properties of Double Perovskites Sr2FeMO6 (M=Mo, W)

雙層鈣鈦礦結構Sr2FeMO6(M=MO, W)之晶體結構，磁性及磁傳導性質

黃昭淵(C. Y. Huang) ； 詹丁山(T. S. Chan) ； 劉汝熹(R. S. Lin) ； 郭光宇(G .Y. Guo)

《華岡工程學報》 17期 (2003/06) Pp. 21-30

https://doi.org/10.29987/CCUHKJE.200306.0002

摘要

我們研究了double perovskites Sr2FeMO6(M=Mo, W)的晶體結構，磁性及磁傳導的性質，所用之材料由固態反應獲得X光分析證明Sr2FeMO6 (SFMO)及Sr2FeWO6(SFWO)分別爲tetragoual (space group:14/mmm)及orthorhomic (space group:1/mmm)磁性量測顯示SFMO爲鐵磁，而SFWO爲反鐵磁在H=5T時，T(下標 N)=35K)我們在室溫時得到SFWO是磁阻比(MR)爲約22% (H=3T)但是SFMO的MR~1%，H=3T，T=300K，算是不顯出。此兩化合物之性質綜合如下SFMO爲半金屬，鐵磁；SFWO爲絕綠體，反鐵磁。此觀測之變化亦由帶計算證實，解釋過度金屬離子之3d (Fe)，4d (Mo)和5d (W)及氧離子之相互作用所產生。

並列摘要

We have investigated the crystal structure, magnetic and magnetotransport properties of double perovskites Sr2FeMO6 (M=Mo, W). The materials have been prepared in polycrystalline by solid state reaction. Powder X-ray diffraction analyses revealed that Sr2FeMoO6 (SFMO) and Sr2FeWO6 (SFWO) have the tetragonal cell (space group: 14/mmm) and the orthorhombic cell (space group: 1mmm), respectively. Magnetic measurements indicate that SFMO is a ferromagnet and SFWO is an antiferromagnet with T(subscript N)=35 K at H 5 T. Large magnetoresistance ratio (MR) of~22% (H=3T) at room temperature (RT) was observed in the SFWO compound. However, the SFMO compound did not show any significant MR even at high fields and RT (MR~1%; H=3 T and 300 K). The properties of these two compounds are summarized as follows: SFMO-half-metallic and ferromagnetic; SFWO-insulator and antiferromagnetic. The changes observed by physical measurements are supported by band structure calculations to explain the interaction between the 3d (Fe) 4d (Mo) and 5d (W) orbitals of transition metal ions and oxygen ions.

並列關鍵字

Magnetoresistance ； half-metallic ； antiferromagnetic ； Sr2FeMoO6 ； Sr2FeWO6