Lee Seokbae, Seo Yu-Seong, Roh Seulki, Song Dongjoon, Eisaki Hiroshi, Hwang Jungseek
Department of Physics, Sungkyunkwan University, Suwon, Gyeonggi-do 16419 Republic of Korea.
National Institute of Advanced Industrial Science and Technology, Tsukuba, 305-8568 Japan.
Sci Rep. 2022 Nov 19;12(1):19950. doi: 10.1038/s41598-022-24520-y.
We investigated four single crystals of K-doped BaFe[Formula: see text]As[Formula: see text] (Ba-122), Ba[Formula: see text]K[Formula: see text]Fe[Formula: see text]As[Formula: see text] with [Formula: see text] 0.29, 0.36, 0.40, and 0.51, using infrared spectroscopy. We explored a wide variety of doping levels, from under- to overdoped. We obtained the superfluid plasma frequencies ([Formula: see text]) and corresponding London penetration depths ([Formula: see text]) from the measured optical conductivity spectra. We also extracted the electron-boson spectral density (EBSD) functions using a two-parallel charge transport channel approach in the superconducting (SC) state. From the extracted EBSD functions, the maximum SC transition temperatures ([Formula: see text]) were determined using a generalized McMillan formula and the SC coherence lengths ([Formula: see text]) were calculated using the timescales encoded in the EBSD functions and reported Fermi velocities. We identified some similarities and differences in the doping-dependent SC quantities between the K-doped Ba-122 and the hole-doped cuprates. We expect that the various SC quantities obtained across the wide doping range will provide helpful information for establishing the microscopic pairing mechanism in Fe-pnictide superconductors.
我们使用红外光谱研究了四种钾掺杂的BaFe₂As₂（Ba-122）单晶，即Ba₂KₓFe₂As₂（x = 0.29、0.36、0.40和0.51）。我们探索了从欠掺杂到过掺杂的各种掺杂水平。我们从测量的光导率光谱中获得了超流等离子体频率（ωₚ）和相应的伦敦穿透深度（λ）。我们还在超导（SC）状态下使用双平行电荷传输通道方法提取了电子-玻色子光谱密度（EBSD）函数。根据提取的EBSD函数，使用广义麦克米兰公式确定了最大超导转变温度（Tₘₐₓ），并使用EBSD函数中编码的时间尺度和报道的费米速度计算了超导相干长度（ξ）。我们确定了钾掺杂的Ba-122和空穴掺杂的铜酸盐之间在掺杂依赖的超导量方面的一些异同。我们期望在宽掺杂范围内获得的各种超导量将为建立铁基超导体中的微观配对机制提供有用信息。
