Observation of Competing Order in a High-$T_{c}$ Superconductor with Femtosecond Optical Pulses

TL;DR

This study uses femtosecond optical pulses to investigate quasiparticle dynamics in a high-$T_c$ superconductor, revealing a competing order that coexists with and suppresses superconductivity below 40 K.

Contribution

First observation of a competing order in a high-$T_c$ superconductor using ultrafast optical techniques, indicating coexistence and competition with superconductivity.

Findings

Identification of a new gap in the density of states

Evidence of a coexistence phase below 40 K

Depression of the superconducting gap due to competing order

Abstract

We present studies of the photoexcited quasiparticle dynamics in Tl$_{2}$Ba$_{2}$Ca$_{2}$Cu$_{3}$O$_{y}$ (Tl-2223) using femtosecond optical techniques. Deep into the superconducting state (below 40 K), a dramatic change occurs in the temporal dynamics associated with photoexcited quasiparticles rejoining the condensate. This is suggestive of entry into a coexistence phase which, as our analysis reveals, opens a gap in the density of states (in addition to the superconducting gap), and furthermore, competes with superconductivity resulting in a depression of the superconducting gap.