First-principles theory of nanoscale pattern formation in ultrathin alloy films: A comparative study of Fe-Ag on Ru(0001) and Mo(110) substrates
First-principles theory of nanoscale pattern formation in ultrathin alloy films: A comparative study of Fe-Ag on Ru(0001) and Mo(110) substrates
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超薄合金薄膜纳米级图案形成的第一性原理理论：Ru(0001)和Mo(110)基底上Fe-Ag的比较研究
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发表时间：
2008
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通讯作者：
M. Asta
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作者：
Bo Yang;T. Muppidi;V. Ozoliņš;M. Asta
在先前提出的混合原子连续模型的框架内，从第一原理研究了单层体不混溶合金膜中纳米级自组装组成图案的形成。物理修订信函88，096101 2002。六方晶系0001和体心立方110衬底的第一性原理计算模型的参数化周围的细节进行了描述，我们演示了如何理论模型可以采用蒙特卡罗模拟作为一个预测框架建模的结构和有限温度稳定性的组成模式。该方法应用在Mo 110和Ru 0001衬底上的等原子FeAg赝晶合金薄膜的比较研究。条纹图案的周期数纳米的预测是稳定的，在这两个系统中，这是在良好的协议与现有的实验数据FeAg/Mo 110。条纹图案的规则性和它们的稳定性相对于无序被发现是大大增强的各向异性的Mo 110基板上相对于近各向同性的Ru 0001表面，尽管在后者系统中的稍微更强的订购能量。本研究的结果进行比较，通常用于描述图案形成的晶体表面的连续理论的预测，突出了这种模型的局限性，在应用程序中的周期性与长度尺度约为10个原子间距的图案。DOI：10.1103/PhysRevB.77.205408
The formation of nanoscale self-assembled compositional patterns in monolayer bulk-immiscible alloy films is studied from first principles within the framework of a previously proposed hybrid atomistic-continuum model V. Ozoliņs et al., Phys. Rev. Lett. 88, 096101 2002. The details surrounding the parametrization of the model from first-principles calculations are described for both hexagonal 0001 and bcc 110 substrates, and we demonstrate how the theoretical model can be employed in Monte Carlo simulations as a predictive framework for modeling the structure and finite-temperature stability of compositional patterns. The methodology is applied in a comparative study of equiatomic FeAg pseudomorphic alloy films on Mo110 and Ru0001 substrates. Stripe patterns with periodicities of a few nanometers are predicted to be stable in both systems, which is in good agreement with available experimental data for FeAg/Mo110. The regularity of the stripe patterns and their stability with respect to disordering are found to be substantially enhanced on the anisotropic Mo110 substrate relative to the nearly isotropic Ru0001 surface, despite the slightly stronger ordering energetics in the latter system. A comparison of the results of the present study to the predictions of continuum theories commonly employed to describe pattern formation on crystalline surfaces serves to highlight the limitations of such models in the application to patterns with periodicities with length scales of approximately ten atomic spacings. DOI: 10.1103/PhysRevB.77.205408