铁基超导体Li_(0.8)Fe_(0.2)ODFeSe的红外光谱研究  

Infrared spectroscopy study of ironbased superconductor Li_(0.8)Fe_(0.2)ODFeSe

作　　者：林桐 胡蝶 时立宇 张思捷 刘妍琦 吕佳林 董涛 赵俊 王楠林 Lin Tong;Hu Die;Shi Li-Yu;Zhang Si-Jie;Liu Yan-Qi;Lv Jia-Lin;Dong Tao;Zhao Jun;Wang Nan-Lin(International Center for Quantum Materials,School of Physics,Peking University,Beijing 100871,China;State Key Laboratory of Surface Physics,Department of Physics,Fudan University,Shanghai 200433,China)

机构地区：[1]北京大学物理学院量子材料科学中心,北京100871 [2]复旦大学物理学系应用表面物理国家重点实验室,上海200433

出　　处：《物理学报》2018年第20期63-68,共6页Acta Physica Sinica

基　　金：国家重点基础研究发展计划(批准号:2016YFA0300902;2016YFA0300203;2017YFA0302904;2015CB921302);国家自然科学基金(批准号:11327806;GZ1123);上海市教育委员会科研创新计划(批准号:2017-01-07-00-07-E00018)资助的课题~~

摘　　要：测量和研究了铁基超导体Li_(0.8)Fe_(0.2)ODFeSe单晶的红外光学响应,发现室温下光电导率谱不存在Drude分量,载流子具有非相干输运行为.随着温度降低,Drude分量形成并不断变窄,同时在相应的反射率谱上出现清晰的等离子体边,表明散射率急剧降低.在最低温度,观察到超导能隙形成导致的光谱变化,光电导率谱在160 cm^(-1)以下受到显著压制.对比FeSe单晶的光谱数据,发现整体的光电导率谱型很相似,但自由载流子的谱重更低,揭示出样品具有更低的载流子浓度.另外还观察到温度变化诱导的谱重由低频向高频区域转移的现象,表明其存在强关联效应.We perform an in-plane optical spectroscopy measurement on iron-based superconductor Li0.8Fe0.2ODFeSe single crystal. At room temperature, the low frequency optical conductivity shows an incoherent characteristic; the Drude component is absent. With temperature decreasing, the Drude component develops and narrows rapidly. A welldefined plasma edge is observed in reflectance spectrum at temperature below 100 K, indicating a dramatically reduced scattering rate. The spectral weight contributed from free carriers is even smaller than that of FeSe single crystal. A number of phonon modes are visible in the measured spectra. We also observe clear spectral change below 160 cm-1 at10 K, associated with the formation of superconducting energy gap in the superconducting state. The energy scale of the superconducting gap is comparable to the value measured by angle-resolved photoemission spectroscopy technique.Like FeSe and other iron pnictides, a clear temperature-induced spectral weight transfer at high energy is observed for Li0.8Fe0.2ODFeSe, indicating the presence of strong correlation effect.

关 键 词：铁基超导体 红外光谱 电子关联 

分 类 号：O511.3[一般工业技术—材料科学与工程]