Ultrafast Pump-Probe Study of Phase Separation and Competing Orders in the Underdoped (Ba, K)Fe2As2 Superconductor

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

Published in: Physical Review Letters 104, 027003, 2010.

We report measurements of quasiparticle relaxation dynamics in the high-temperature superconductor (Ba, K)Fe2As2  in optimally doped, underdoped, and undoped regimes. In the underdoped sample, spin-density wave (SDW) order forms at ~85 K, followed by superconductivity at ~28 K. We find the emergence of a normal-state order that suppresses SDW at a temperature T* ~60 K and argue that this normal-state order is a precursor to superconductivity.

DOI: 10.1103/PhysRevLett.104.027003