Giant Surface Magnetostriction: Fundamental Investigations

这项研究包括一系列的测量，旨在对巨表面磁致伸缩有一个更彻底和基本的了解。在磁性薄膜表面附近，有效磁弹性系数可以取异常大的值。研究了镍/铜、镍/银、钴/铜、铁/银和铁/钨外延单晶薄膜中主磁弹性系数的厚度依赖性。寻求对表面磁弹性的基本理解，特别是关于其正确的大小、对称性、温度依赖性和尼尔系数的物理意义。材料表面磁弹性系数的第一性原理计算将与本程序中测量的实验值进行比较。这项工作将为建立关于不同界面材料对表面磁弹性效应影响的预测能力提供坚实的基础。通过比较不同金属在不同温度下的表面磁弹性异常范围，验证了高局域表面效应扩展范围的交换相互作用模型。这些观察结果具有重要的技术意义，因为似乎薄膜磁性器件的表面条件对控制磁性，特别是各向异性、磁导率和噪声，甚至在名义上为零磁致伸缩的组合物中，都具有增强的重要性。＊＊＊

9410943 R. O'Handley This research involves a series of measurements directed toward a more thorough and fundamental understanding of giant surface magnetostriction. Effective magnetoelastic coefficients can take on anomalously large values near the surface of magnetic thin films. The thickness dependence of the principal magnetoelastic coefficients is examined in epitaxial single crystal nickel/copper, nickel/silver, cobalt/copper, iron/silver, and iron/tungsten thin films. A fundamental understanding of surface magnetoelasticity is sought, particularly concerning its correct magnitude, symmetry, temperature dependence, and the physical significance of the Neel coefficients. First principle calculations for the surface magnetoelastic coefficients of materials will be compared to experimental values measured in this program. This work should provide a sound fundamental basis for creating a predictive capability with respect to the effects of different interface materials on surface magnetoelastic effects. An exchange interaction model for the extended range of the highly localized surface effect will be tested by comparing the range of the surface magnetoelastic anomaly for different metals at different temperatures. %%% These observations have important technical consequences, since it appears that the surface conditions of thin film magnetic devices are of enhanced importance in controlling magnetic properties, especially anisotropy, permeability, and noise, even in compositions of nominally zero magnetostriction. ***