title: Ultrafast pump-probe study of phase separation and competing orders in the underdoped (Ba,K)Fe2As2 superconductor.
abstract: 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 approximately 85 K, followed by superconductivity at approximately 28 K. We find the emergence of a normal-state order that suppresses SDW at a temperature T{*} approximately 60 K and argue that this normal-state order is a precursor to superconductivity.
authors.affiliation: Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore.
authors.forename: Elbert E M
authors.initials: EE
authors.lastname: Chia
authors.forename: D
authors.initials: D
authors.lastname: Talbayev
authors.forename: Jian-Xin
authors.initials: JX
authors.lastname: Zhu
authors.forename: H Q
authors.initials: HQ
authors.lastname: Yuan
authors.forename: T
authors.initials: T
authors.lastname: Park
authors.forename: J D
authors.initials: JD
authors.lastname: Thompson
authors.forename: C
authors.initials: C
authors.lastname: Panagopoulos
authors.forename: G F
authors.initials: GF
authors.lastname: Chen
authors.forename: J L
authors.initials: JL
authors.lastname: Luo
authors.forename: N L
authors.initials: NL
authors.lastname: Wang
authors.forename: A J
authors.initials: AJ
authors.lastname: Taylor