Lin Kung-Hsuan, Wang Kuan-Jen, Chang Chung-Chieh, Wen Yu-Chieh, Lv Bing, Chu Ching-Wu, Wu Maw-Kuen
Institute of Physics, Academia Sinica, Taipei 11529, Taiwan.
Institute of Photonics Technologies, National Tsing Hua University, Hsinchu 30013, Taiwan.
Sci Rep. 2016 May 16;6:25962. doi: 10.1038/srep25962.
We have utilized ultrafast optical spectroscopy to study carrier dynamics in slightly underdoped (BaK)Fe2As2 crystals without magnetic transition. The photoelastic signals due to coherent acoustic phonons have been quantitatively investigated. According to our temperature-dependent results, we found that the relaxation component of superconducting quasiparticles persisted from the superconducting state up to at least 70 K in the normal state. Our findings suggest that the pseudogaplike feature in the normal state is possibly the precursor of superconductivity. We also highlight that the pseudogap feature of K-doped BaFe2As2 is different from that of other iron-based superconductors, including Co-doped or P-doped BaFe2As2.
我们利用超快光学光谱研究了无磁转变的略欠掺杂（BaK）Fe2As2晶体中的载流子动力学。对相干声子引起的光弹信号进行了定量研究。根据我们的温度相关结果，我们发现超导准粒子的弛豫分量从超导态一直持续到正常态至少70 K。我们的发现表明，正常态中的类赝能隙特征可能是超导性的前兆。我们还强调，K掺杂BaFe2As2的赝能隙特征与其他铁基超导体不同，包括Co掺杂或P掺杂的BaFe2As2。
