Wednesday, June 26, 2013

1306.5817 (Wei Li et al.)

Orbital-Selective Mottness in KxFe2-ySe2 Superconductors Revealed by
Pump-Probe Spectroscopy

Wei Li, Chunfeng Zhang, Shenghua Liu, Xiaxin Ding, Xuewei Wu, Xiaoyong Wang, Hai-Hu Wen, Min Xiao
We report transient optical signatures of the orbital-selective Mottness in superconducting KxFe2-ySe2 crystals by using dual-color pump-probe spectroscopy. Besides multi-exponential decay recovery dynamics of photo-induced quasiparticles, a damped oscillatory component due to coherent acoustic phonons emerges when the superconducting phase is suppressed by increasing the temperature or excitation power. The oscillatory component diminishes with significant enhancement of a slow decay component upon raising temperature to 150-160 K. These results are in consistence with the picture of orbital-selective Mott phase transition, indicating a vital role played by electron correlation in the iron-based superconductors.
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