铁基超导体Li0.8Fe0.2ODFeSe的红外光谱研究

林桐; 胡蝶; 时立宇; 张思捷; 刘妍琦; 吕佳林; 董涛; 赵俊; 王楠林

doi:10.7498/aps.67.20181401

摘要

测量和研究了铁基超导体Li0.8Fe0.2ODFeSe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.

关键词:

Abstract

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 well-defined 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 at 10 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.

Keywords:

作者及机构信息

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

通信作者: 王楠林, nlwang@pku.edu.cn

基金项目: 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）和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.

Authors and contacts

1.
International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China;

2.
State Key Laboratory of Surface Physics, Department of Physics, Fudan University, Shanghai 200433, China

Corresponding author: Wang Nan-Lin, nlwang@pku.edu.cn

Funds: Project supported by the National Basic Research Program of China (Grant Nos. 2016YFA0300902, 2016YFA0300203, 2017YFA0302904, 2015CB921302), the National Natural Science Foundation of China (Grant Nos. 11327806, GZ1123), and the Innovation Program of Shanghai Municipal Education Commission, China (Grant No. 2017-01-07-00-07-E00018).

参考文献

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[17]	Li G, Hu W Z, Dong J, Li Z, Zheng P, Chen G F, Luo J L, Wang N L 2008 Phys. Rev. Lett. 101 107004
[18]	Yuan R H, Kong W D, Yan L, Ding H, Wang N L 2013 Phys. Rev. B 87 144517
[19]	Hu W Z, Dong J, Li G, Li Z, Zheng P, Chen G F, Luo J L, Wang N L 2008 Phys. Rev. Lett. 101 257005
[20]	Hu W Z, Li G, Zheng P, Chen G F, Luo J L, Wang N L 2009 Phys. Rev. B 80 100507
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施引文献

[1]	Rotter M, Tegel M, Johrendt D 2008 Phys. Rev. Lett. 101 107006
[2]	Kuroki K, Onari S, Arita R, Usui H, Tanaka Y, Kontani H, Aoki H 2008 Phys. Rev. Lett. 101 087004
[3]	Guo J G, Jin S F, Wang G, Wang S C, Zhu K X, Zhou T T, He M, Chen X L 2010 Phys. Rev. B 82 180520
[4]	Margadonna S, Takabayashi Y, Ohishi Y, Mizuguchi Y, Takano Y, Kagayama T, Nakagawa T, Takata M, Prassides K 2009 Phys. Rev. B 80 064506
[5]	Wang H P, Ye Z R, Zhang Y, Wang N L 2016 Sci. Bull. 61 1126
[6]	Liu D F, Zhang W H, Mou D X, He J F, Ou Y B, Wang Q Y, Li Z, Wang L L, Zhao L, He S L, Peng Y Y, Liu X, Chen C Y, Yu L, Liu G D, Dong X L, Zhang J, Chen C T, Xu Z Y, Hu J P, Chen X, Ma X C, Xue Q K, Zhou X J 2012 Nat. Commun. 3 931
[7]	He S L, He J F, Zhang W H, Zhao L, Liu D F, Liu X, Mou D X, Ou Y B, Wang Q Y, Li Z, Wang L L, Peng Y Y, Liu Y, Chen C Y, Yu L, Liu G D, Dong X L, Zhang J, Chen C T, Xu Z Y, Chen X, Ma X C, Xue Q K, Zhou X J 2013 Nat. Mater. 12 605
[8]	Tan S Y, Zhang Y, Xia M, Ye Z Y, Chen F, Xie X, Peng R, Xu D F, Fan Q, Xu H C, Jiang J, Zhang T, Lai X C, Xiang T, Hu J P, Xie B P, Feng D L 2013 Nat. Mater. 12 634
[9]	Zhang Z C, Wang Y H, Song Q, Liu C, Peng R, Moler K A, Feng D L, Wang Y Y 2015 Sci. Bull. 60 1301
[10]	Lu X F, Wang N Z, Wu H, Wu Y P, Zhao D, Zeng X Z, Luo X G, Wu T, Bao W, Zhang G H, Huang F Q, Huang Q Z, Chen X H 2015 Nat. Mater. 14 325
[11]	Dong X L, Jin K, Yuan D N, Zhou H X, Yuan J, Huang Y L, Hua W, Sun J L, Zheng P, Hu W, Mao Y Y, Ma M W, Zhang G M, Zhou F, Zhao Z X 2015 Phys. Rev. B 92 064515
[12]	Niu X H, Peng R, Xu H C, Yan Y J, Jiang J, Xu D F, Yu T L, Song Q, Huang Z C, Wang Y X, Xie B P, Lu X F, Wang N Z, Chen X H, Sun Z, Feng D L 2015 Phys. Rev. B 92 060504
[13]	Yan Y J, Zhang W H, Ren M Q, Liu X, Lu X F, Wang N Z, Niu X H, Fan Q, Miao J, Tao R, Xie B P, Chen X H, Zhang T, Feng D L 2016 Phys. Rev. B 94 134502
[14]	Zhao L, Liang A J, Yuan D N, Hu Y, Liu D F, Huang J W, He S L, Shen B, Xu Y, Liu X, Yu L, Liu G D, Zhou H X, Huang Y L, Dong X L, Zhou F, Liu K, Lu Z Y, Zhao Z X, Chen C T, Xu Z Y, Zhou X J 2016 Nat. Commun. 7 10608
[15]	Pan B Y, Shen Y, Hu D, Feng Y, Park J T, Christianson A D, Wang Q S, Hao Y Q, Wo H L, Yin Z P, Maier T A, Zhao J 2017 Nat. Commun. 8 123
[16]	Tanner D B 2015 Phys. Rev. B 91 035123
[17]	Li G, Hu W Z, Dong J, Li Z, Zheng P, Chen G F, Luo J L, Wang N L 2008 Phys. Rev. Lett. 101 107004
[18]	Yuan R H, Kong W D, Yan L, Ding H, Wang N L 2013 Phys. Rev. B 87 144517
[19]	Hu W Z, Dong J, Li G, Li Z, Zheng P, Chen G F, Luo J L, Wang N L 2008 Phys. Rev. Lett. 101 257005
[20]	Hu W Z, Li G, Zheng P, Chen G F, Luo J L, Wang N L 2009 Phys. Rev. B 80 100507
[21]	Wang N L, Hu W Z, Chen Z G, Yuan R H, Li G, Chen G F, Xiang T 2012 J. Phys.: Condens. Matter 24 294202
[22]	Benfatto L, Cappelluti E, Ortenzi L, Boeri L 2009 Nat. Phys. 5 647
[23]	Qazilbash M M, Hamlin J J, Baumbach R E, Zhang L J, Singh D J, Maple M B, Basov D N 2009 Nat. Phys. 5 647

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