Fachbereich Physik, Philipps Universität, Renthof 6, 35032 Marburg, Germany.
Phys Rev Lett. 2011 Apr 8;106(14):146402. doi: 10.1103/PhysRevLett.106.146402. Epub 2011 Apr 7.
We investigate multiband Hubbard models for the three iron 3d t(2g) bands and the two iron 3d e(g) bands in LaOFeAs by means of the Gutzwiller variational theory. Our analysis of the paramagnetic ground state shows that neither Hartree-Fock mean-field theories nor effective spin models describe these systems adequately. In contrast to Hartree-Fock-type approaches, the Gutzwiller theory predicts that antiferromagnetic order requires substantial values of the local Hund's-rule exchange interaction. For the three-band model, the antiferromagnetic moment fits experimental data for a broad range of interaction parameters. However, for the more appropriate five-band model, the iron e(g) electrons polarize the t(2g) electrons and they substantially contribute to the ordered moment.
我们通过 Gutzwiller 变分理论研究了 LaOFeAs 中三个铁 3d t(2g) 带和两个铁 3d e(g) 带的多带 Hubbard 模型。我们对顺磁基态的分析表明，哈特利-福克平均场理论和有效自旋模型都不能充分描述这些体系。与哈特利-福克型方法相反，Gutzwiller 理论预测反铁磁有序需要局域 Hund 规则交换相互作用的大量值。对于三能带模型，反铁磁矩适合于广泛的相互作用参数的实验数据。然而，对于更合适的五能带模型，铁 e(g) 电子极化 t(2g) 电子，并对有序矩有很大贡献。
