产生非平衡光激发中心对La2CuO4超交换的隙内激发效应
In-gap excitation effect on a superexchange in La2CuO4 by creating nonequilibrium photoexcited centers
摘要：
本文提出了一种多电子方法来计算磁性Mott-Hubbard绝缘体La_2CuO_4（又称La_（214））中的超交换相互作用，该方法可以获得光泵浦对超交换相互作用的影响。我们使用的细胞微扰理论与精确对角化的多带PD哈密顿量内的每个CuO 6晶胞和治疗细胞间的跳跃作为微扰。为了考虑光抽运的影响，我们在这项工作中包括激发的单空穴局域态以及所有的双空穴单重态和三重态。通过投影出带间电子跳跃，我们得到了有效的类海森堡哈密顿量，其中Ri处的局域自旋是基态和激发单空穴态的叠加。我们发现，在隙内激发单空穴态的共振光占据下，反铁磁对La_（214）交换能的贡献将按~ 4 × 10_{-3} eV /（%）的比例增加。
英文摘要：
We propose a multielectron approach to calculate superexchange interaction in magnetic Mott- Hubbard insulator La2CuO4(further La214) that allows to obtain the effect of optical pumping on the superexchange interaction. We use the cell perturbation theory with exact diagonalization of the multiband pd Hamiltonian inside each CuO6 unit cell and treating the intercell hopping as perturbation. To incorporate effect of optical pumping we include in this work the excited singlehole local states as well as all two-hole singlets and triplets. By projecting out the interband intercell electron hopping we have obtained the effective Heisenberg-like Hamiltonian with the local spin at site Ri being a superposition of the ground and excited single-hole states. We found that antiferromagnetic contribution to the exchange energy in La214 will increase in accordance to ~ 4*10_{-3} eV /(%) at the resonance light occupation of the excited single hole in-gap state.
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