We use coherent pump-probe spectroscopy to measure the photoinduced reflectivity DeltaR, and complex dielectric function, {delta}in, of the electron-doped cuprate superconductor Nd_{2-x}Ce_xCuO_{4+delta} at a value of x near optimal doping, as a function of time, temperature, and laser fluence. We observe the onset of a negative DeltaR at T=85 K, above the superconducting transition temperature, T_c, of 23 K, that exhibits a form of scaling consistent with critical fluctuations in the time domain. A positive Delta R onsets at T_c that we associate with superconducting order. We find that the two signals are strongly coupled below T_c, in a manner that suggests a repulsive interaction between superconductivity and antiferromagnetic correlations.
تحميل البحث