Signatures of superconducting and pseudogap phases in ultrafast transient reflectivity of Ca(Fe0.927Co0.073)2As2

Abstract

We present femtosecond time-resolved pump-probe spectroscopic studies of a pseudogap (PG) along with the superconducting (SC) gap in an overdoped iron pnictide Ca(Fe0.927Co0.073)2As2. It is seen that the temperature evolution of the photoexcited quasiparticle (QP) relaxation dynamics, coherently excited A1g-symmetric optical phonon and two acoustic phonon dynamics behave anomalously in the vicinity of the superconducting transition temperature Tc. A continuous change in the sign of the experimentally measured transient differential reflectivity Delta_R/R signal at the zero time-delay between the pump and probe pulses at a temperature of ~200 K is inferred as an evidence of the emergence of the PG phase around that temperature. This behavior is independent of the pump photon energy and occurs for crystals without the spin density wave phase transition.

EPL (2014)

References in corpus (10)

• Superconductivity in Iron Compounds
• Spin susceptibility, phase diagram, and quantum criticality in the electron-doped high Tc Superconductor Ba[Fe(1-x)Co(x)]2As2
• 19-F NMR Investigation of Iron-pnictide Superconductor LaFeAsO(0.89)F(0.11)
• Abrupt transition in quasiparticle dynamics at optimal doping in a cuprate superconductor system
• Infrared Measurement of the Pseudogap in P-Doped and Co-Doped BaFe2As2 High-Temperature Superconductors
• Doping dependence of femtosecond quasi-particle relaxation dynamics in Ba(Fe,Co)_2As_2 single crystals: possible evidence for normal state nematic fluctuations
• Pseudogap in underdoped Ba${}_{1-x}$K${}_x$Fe${}_2$As${}_2$ as seen via optical conductivity
• Acoustic and optical phonon dynamics from femtosecond time-resolved optical spectroscopy of superconducting iron pnictide Ca(Fe_0.944Co_0.056)_2As_2
• Ultrafast quasiparticle dynamics in superconducting iron pnictide CaFe1.89Co0.11As2
• Gap-dependent quasiparticle dynamics and coherent acoustic phonons in parent iron pnictide CaFe2As2 across the spin density wave phase transition

Cited by in corpus (1)

• Non-equilibrium phenomena in superconductors probed by femtosecond time-domain spectroscopy