Multiple antiferromagnet/ferromagnet interfaces as a probe of grain-size-dependent exchange bias in polycrystalline Co/Fe50Mn50
Multiple antiferromagnet/ferromagnet interfaces as a probe of grain-size-dependent exchange bias in polycrystalline Co/Fe50Mn50
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DOI：
10.1016/j.jmmm.2006.06.011
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发表时间：
2007-02-01
影响因子：
2.7
通讯作者：
Leighton, C.
中科院分区：
文献类型：
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作者：
Bolon, Bruce T.;Haugen, M. A.;Leighton, C.
我们使用铁磁体/反铁磁体/铁磁体三层和铁磁体/反铁磁体多层来研究Co/Fe50Mn50多晶中交换偏置的晶粒尺寸依赖性。x射线衍射和透射电镜结果表明，在Co（30埃）/FeMn体系中，Fe50Mn50 （FeMn）晶粒尺寸随着FeMn厚度的增加而增大。因此，在Co（30埃）/FeMn（t（AF）埃）/ Co（30埃）三层中，两个Co层在两个反铁磁体/铁磁体界面处取样不同的FeMn晶粒尺寸。对于超过100埃的FeMn厚度，其中简单的双层具有与厚度无关的交换偏置，因此我们能够通过测量具有不同FeMn厚度的三层和多层样品来推断FeMn晶粒尺寸对交换偏置和矫顽力（及其温度依赖性）的影响。这可以在保持（111）取向的同时完成，并且界面粗糙度变化很小。将平均晶粒尺寸从90埃增加到135埃，交换偏置降低了四倍，与晶粒尺寸相反。我们将结果解释为随着反铁磁体晶粒尺寸的增加，非补偿自旋密度减少，进一步证明了缺陷产生的非补偿自旋的重要性。(c) 2006 Elsevier B.V.版权所有
We have used ferromagnet/antiferromagnet/ferromagnet trilayers and ferromagnet/antiferromagnet multilayers to probe the grain size dependence of exchange bias in polycrystalline Co/Fe50Mn50. X-ray diffraction and transmission electron microscopy show that the Fe50Mn50 (FeMn) grain size increases with increasing FeMn thickness in the Co (30 angstrom)/FeMn system. Hence, in Co(30 angstrom)/FeMn(t(AF) angstrom)/ Co(30 angstrom) trilayers the two Co layers sample different FeMn grain sizes at the two antiferromagnet/ferromagnet interfaces. For FeMn thicknesses above 100 angstrom, where simple bilayers have a thickness-independent exchange bias, we are therefore able to deduce the influence of FeMn grain size on the exchange bias and coercivity (and their temperature dependence) simply by measuring trilayer and multilayer samples with varying FeMn thicknesses. This can be done while maintaining the (111) orientation, and with little variation in interface roughness. Increasing the average grain size from 90 to 135 angstrom results in a fourfold decrease in exchange bias, following an inverse grain size dependence. We interpret the results as being due to a decrease in uncompensated spin density with increasing antiferromagnet grain size, further evidence for the importance of defect-generated uncompensated spins. (c) 2006 Elsevier B.V. All rights reserved.