Orbitally driven spin-singlet dimerization in S=1 La4Ru2O10
Orbitally driven spin-singlet dimerization in S=1 La4Ru2O10
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DOI：
10.1103/physrevlett.96.256402
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发表时间：
2006-06-30
影响因子：
8.6
通讯作者：
Tjeng, L. H.
中科院分区：
文献类型：
--
作者：
Wu, Hua;Hu, Z.;Tjeng, L. H.
利用Ru-L-2，L-3边的X射线吸收谱，我们揭示了Ru~(4+)离子在罕见的4d轨道有序跃迁和自旋能隙形成过程中保持在S=1的自旋态。用局域自旋密度近似+Hubbard U带结构计算发现，低温相中的晶场不足以稳定S=0态。取而代之的是，我们确定了具有显著各向异性的反铁磁交换耦合的独特轨道有序。我们得出结论：La_4Ru_2O_(10)是一种轨道物理驱动准二维S=1体系中自旋单重态二聚体形成的新材料。
Using x-ray absorption spectroscopy at the Ru-L-2,L-3 edge we reveal that the Ru4+ ions remain in the S=1 spin state across the rare 4d-orbital ordering transition and spin-gap formation. We find using local spin density approximation+Hubbard U band structure calculations that the crystal fields in the low-temperature phase are not strong enough to stabilize the S=0 state. Instead, we identify a distinct orbital ordering with a significant anisotropy of the antiferromagnetic exchange couplings. We conclude that La4Ru2O10 appears to be a novel material in which the orbital physics drives the formation of spin-singlet dimers in a quasi-two-dimensional S=1 system.