Preparation and characterisation of the double perovskite Sr₂TaMnO₆

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• 作者：Martin Valldor ; Saeid Esmaeilzadeh ; Magnus Andersson and Andrzej Morawski
• 关键词：Spin glass ; Insulator ; Frequency dependence ; Double-exchange ; NPD
• 刊名：Journal of Magnetism and Magnetic Materials
• 出版年：2006
• 出版时间：April 2006
• 年：2006
• 卷：299
• 期：1
• 页码：161-169
• 全文大小：359 K

文摘

The presented compound, Sr₂TaMnO₆, has a weak, disordered magnetic structure. The metal oxide was prepared under high isostatic oxygen pressure. The doubling of the perovskite structure was proven with electron diffraction and powder neutron diffraction. Combining neutron- and X-ray diffraction data, the room-temperature structure was modelled with the Rietveld method. Both octahedral positions are partially occupied by Mn and Ta, but with different Mn/Ta ratios. AC- and DC-magnetic measurements indicate a magnetic transition at about 17 K and the AC-magnetic susceptibility, both real and imaginary part, is frequency dependent, suggesting that the material has a spin-glass feature. The magnetic spins freeze during a wide temperature range and a possible explanation is a competative situation between the double exchange (ferromagnetism) and the super-exchange (anti-ferromagnetism).