Amorphous Fe–B alloys in B–Fe–Ag multilayers studied by magnetization and Mössbauer measurements

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• 作者：L.F. Kiss^a ; ^{kissl@szfki.hu"" rel=""nofollow} ; J. Balogh^a ; L. Bujdos&#xf3 ; ^a ; D. Kaptá ; s^a ; T. Kemé ; ny^a ; A. Ková ; cs^b ; I. Vincze^a
• 关键词：Magnetic multilayers ; Amorphous materials ; Vapor deposition ; Magnetic measurements ; M&#xf6 ; ssbauer spectroscopy ; Atomic scale structure
• 刊名：Journal of Alloys and Compounds
• 出版年：2011
• 出版时间：June 2011
• 年：2011
• 卷：509
• 期：Complete
• 页码：S188-S192
• 全文大小：622 K

文摘

Bulk and local magnetic properties were studied in [1 nm B + 1 nm ⁵⁷Fe + x nm Ag]₅, x = 1, 2, 4, 5 and 10, multilayer samples. Although Ag does not mix with either of the other two elements the magnetic properties of the multilayers are strongly influenced by the Ag thickness below x = 5, whereas no such effect is observed above this value. The Mössbauer measurements indicate a complete amorphization of the thin Fe layers in each sample, as a result of intermixing with the B layers. The variation of the magnetic properties is explained by the variation of the average B concentration of the amorphous Fe–B layers, which depends on the thickness of the Ag barrier layers. The magnetization measurements indicate ferromagnetic behaviour of the ultra-thin amorphous layers with the presence of less than 10 % superparamagnetic moments for x = 5 and 10. The average B concentration of the amorphous Fe–B alloy, as estimated from the Fe hyperfine fields, is around 40 at % . It is significantly lower than the 60 at % nominal B concentration, suggesting the presence of an unalloyed B layer, as well. This picture is supported by transmission electron microscopy investigations which reveal two amorphous layers of different B concentration in between the crystalline Ag layers.