Stabilization of d-band ferromagnetism by hybridization with uncorrelated bands
Stabilization of d-band ferromagnetism by hybridization with uncorrelated bands
复制标题
通过与不相关带杂化稳定 d 带铁磁性
DOI：
10.1103/physrevb.64.144415
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发表时间：
2001
影响因子：
3.7
通讯作者：
W. Nolting
中科院分区：
文献类型：
--
作者：
S. Schwieger;W. Nolting
我们研究了s-d或p-d杂化对d带铁磁性的影响，以估计杂化对过渡金属磁性的重要性。为了集中我们的注意力杂交和相关性之间的相互作用，我们调查了一个简单的模型系统，由两个非退化的杂交带，一个强相关，另一个准自由。为了解决这个扩展的哈伯德模型，我们采用简单的近似，即SDA和MAA，关于单带模型中的铁磁性，已知给出定性满意的结果。这种方法使我们能够讨论的基本机制，其中d-带铁磁性的影响的基础上的杂交的解析表达式。后者清楚地显示了重要效应的顺序和函数依赖关系。研究发现，自旋相关的带间粒子涨落引起Hubbard带的自旋相关的带移和带增宽。位移稳定了，加宽倾向于破坏铁磁性。稳定化需要相对高的谱带距离和小的杂化矩阵元素。超交换和RKKY耦合是次要的。
We investigate the influence of s-d or p-d hybridization to d-band ferromagnetism to estimate the importance of hybridization for the magnetic properties of transition metals. To focus our attention to the interplay between hybridization and correlation we investigate a simple model system consisting of two non-degenerated hybridized bands, one strongly correlated, the other one quasi-free. To solve this extended Hubbard model, we apply simple approximations, namely SDA and MAA, that, concerning ferromagnetism in the single-band model, are known to give qualitatively satisfactory results. This approach allows us to discuss the underlying mechanism, by which d-band ferromagnetism is influenced by the hybridization on the basis of analytical expressions. The latter clearly display the order and the functional dependencies of the important effects. It is found, that spin-dependent inter-band particle fluctuations cause a spin-dependent band shift and a spin-dependent band broadening of the Hubbard bands. The shift stabilizes, the broadening tends to destabilize ferromagnetism. Stabilization requires relatively high band distances and small hybridization matrix elements. Super-exchange and RKKY coupling are of minor importance.