Elastic and chemical contributions to the stability of magnetic surface alloys on Ru(0001)
Elastic and chemical contributions to the stability of magnetic surface alloys on Ru(0001)
复制标题
弹性和化学对 Ru(0001) 磁性表面合金稳定性的贡献
DOI：
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
S. Narasimhan
中科院分区：
文献类型：
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作者：
M. Marathe;M. Imam;S. Narasimhan
我们用密度泛函理论研究了表面合金的结构稳定性。我们的系统由Ru（0001）表面上的$M_xN_{1-x}$赝晶层组成，其中$M$ = Fe或Co，$N$ = Pt，Au，Ag，Cd或Pb。我们研究的几种组合显示出对原子混合构型的偏好，而不是相分离的形式。我们还进行了进一步的{it ab initio}计算，以获得描述合金层中原子之间的弹性相互作用的参数，包括表面的有效原子尺寸。我们发现，虽然弹性相互作用有利于合金化的所有系统，我们认为，在某些情况下，化学相互作用不利于原子混合。我们表明，一个简单的标准（类似于休谟-Rothery第一定律的大块合金）不一定工作的应变稳定的表面合金，因为存在额外的弹性贡献的合金的形成热，这将倾向于反对相分离。
We have used density functional theory to study the structural stability of surface alloys. Our systems consist of a single pseudomorphic layer of $M_xN_{1-x}$ on the Ru(0001) surface, where $M$ = Fe or Co, and $N$ = Pt, Au, Ag, Cd, or Pb. Several of the combinations studied by us display a preference for atomically mixed configurations over phase-segregated forms. We have also performed further {it ab initio} calculations to obtain the parameters describing the elastic interactions between atoms in the alloy layer, including the effective atomic sizes at the surface. We find that while elastic interactions favor alloying for all the systems considered by us, in some cases chemical interactions disfavor atomic mixing. We show that a simple criterion (analogous to the Hume-Rothery first law for bulk alloys) need not necessarily work for strain-stabilized surface alloys, because of the presence of additional elastic contributions to the alloy heat of formation, that will tend to oppose phase segregation.