arXiv 0809.40972008-09cond-mat.supr-concond-mat.str-el

Ultrafast pump-probe study of phase separation and competing orders in the underdoped (Ba,K)Fe$_{2}$As$_{2}$ superconductor

Elbert E. M. Chia, D. Talbayev, J. -X. Zhu, H. Q. Yuan, T. Park, J. D. Thompson, C. Panagopoulos, G. F. Chen, J. L. Luo, N. L. Wang, A. J. Taylor

备注：: Major revision
发表信息：: Phys. Rev. Lett.104, 027003 (2010)

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We report measurements of quasiparticle relaxation dynamics in the high-temperature superconductor (Ba,K)Fe$_{2}$As$_{2}$ in optimally doped, underdoped and undoped regimes. In the underdoped sample, spin-density wave (SDW) order forms at $\sim$85 K, followed by superconductivity at $\sim$ 28 K. We find the emergence of a normal-state order that suppresses SDW at a temperature $T^{\ast} \sim$ 60 K and argue that this normal-state order is a precursor to superconductivity.

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