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Optical spectroscopy of single-crystalline LaFeAsO

2010; American Physical Society; Volume: 81; Issue: 10 Linguagem: Inglês

10.1103/physrevb.81.100502

1550-235X

Zhiguo Chen, R. H. Yuan, Tao Dong, N. L. Wang,

Rare-earth and actinide compounds

Millimeter-sized single crystals of LaFeAsO were grown from NaAs flux and the in-plane optical properties were studied over a wide frequency range. A sizable electronic correlation effect was indicated from the analysis of the free-carrier spectral weight. With decreasing temperature from 300 K, we observed a continuous suppression of the spectral weight near 0.6 eV. But a spin-density-wave gap formation at lower energy scale was seen only in the broken-symmetry state. We elaborate that both the itinerancy and local-spin interactions of $\text{Fe}\text{ }3d$ electrons are present for the FeAs-based systems; however, the establishment of the long-range magnetic order at low temperature has a dominantly itinerant origin.