We use femtosecond time-resolved optical reflectivity to study the photoexcited quasiparticle (QP) dynamics in the iron-based 112 type superconducting (SC) samples Ca 0.82 La 0.18 Fe 1 – x Ni x As 2 , with x = 0 and 0.024. In the parent sample, a fast and a slow relaxation emerge at temperatures below the magnetic-structure (MS) transition T ms ≈ 50 K and the SC transition T c ≈ 33 K, respectively. The latter obviously corresponds to an SC QP dynamics, which is further confirmed in the x = 0.024 sample with T c ≈ 25 K. The former suggests that a partial of photoexcited QP relaxation through a pesudogap (PG) channel, which is absent in the doped x = 0.024 sample without the MS transition .

中文翻译：

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Ca 0.82 La 0.18 Fe 1 – x Ni x As 2中Pseeudogap和超导拟粒子动力学的时间分辨研究

我们使用飞秒时间分辨的光学反射率来研究铁基112型超导（SC）样品Ca 0.82 La 0.18 Fe 1-x Ni x As 2（x = 0和0.024）中的光激发准粒子（QP）动力学。在母体样品中，在低于磁结构（MS）跃迁T ms≈50 K和SC跃迁T c≈33 K的温度下，出现了快速弛豫和缓慢弛豫。后者显然对应于SC QP动力学，这在x = 0.024且T c≈25 K的样品中得到了进一步证实。前者表明一部分光敏QP通过pesudogap（PG）通道弛豫，而在pesudogap（PG）通道中则不存在。掺杂x = 0.024样品，无MS跃迁。