中国物理B ›› 2018, Vol. 27 ›› Issue (7): 77405-077405.doi: 10.1088/1674-1056/27/7/077405

• CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES • 上一篇    下一篇

Effect of Mn substitution on superconductivity in iron selenide (Li, Fe)OHFeSe single crystals

Yiyuan Mao(毛义元), Zian Li(李子安), Huaxue Zhou(周花雪), Mingwei Ma(马明伟), Ke Chai(柴可), Shunli Ni(倪顺利), Shaobo Liu(刘少博), Jinpeng Tian(田金鹏), Yulong Huang(黄裕龙), Jie Yuan(袁洁), Fang Zhou(周放), Jianqi Li(李建奇), Kui Jin(金魁), Xiaoli Dong(董晓莉), Zhongxian Zhao(赵忠贤)   

  1. 1 Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Science, Beijing 100190, China;
    2 University of Chinese Academy of Sciences, Beijing 100049, China;
    3 School of Physic, Beijing Institute of Technology, Beijing 100081, China
  • 收稿日期:2018-05-11 修回日期:2018-05-15 出版日期:2018-07-05 发布日期:2018-07-05
  • 通讯作者: Xiaoli Dong, Zhongxian Zhao E-mail:dong@iph.ac.cn;zhxzhao@iphy.ac.cn
  • 基金资助:

    Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFA0303003 and 2016YFA0300300), the National Natural Science Foundation of China (Grant No. 11574370), and the Strategic Priority Research Program and Key Research Program of Frontier Sciences of the Chinese Academy of Sciences (Grant Nos. QYZDY-SSW-SLH001, QYZDY-SSW-SLH008, and XDB07020100).{These authors contributed equally to this work.

Effect of Mn substitution on superconductivity in iron selenide (Li, Fe)OHFeSe single crystals

Yiyuan Mao(毛义元)1,2, Zian Li(李子安)1,2, Huaxue Zhou(周花雪)1, Mingwei Ma(马明伟)1,2, Ke Chai(柴可)3, Shunli Ni(倪顺利)1,2, Shaobo Liu(刘少博)1,2, Jinpeng Tian(田金鹏)1,2, Yulong Huang(黄裕龙)1,2, Jie Yuan(袁洁)1, Fang Zhou(周放)1,2, Jianqi Li(李建奇)1,2, Kui Jin(金魁)1,2, Xiaoli Dong(董晓莉)1,2, Zhongxian Zhao(赵忠贤)1,2   

  1. 1 Beijing National Laboratory for Condensed Matter Physics and Institute of Physics, Chinese Academy of Science, Beijing 100190, China;
    2 University of Chinese Academy of Sciences, Beijing 100049, China;
    3 School of Physic, Beijing Institute of Technology, Beijing 100081, China
  • Received:2018-05-11 Revised:2018-05-15 Online:2018-07-05 Published:2018-07-05
  • Contact: Xiaoli Dong, Zhongxian Zhao E-mail:dong@iph.ac.cn;zhxzhao@iphy.ac.cn
  • Supported by:

    Project supported by the National Key Research and Development Program of China (Grant Nos. 2017YFA0303003 and 2016YFA0300300), the National Natural Science Foundation of China (Grant No. 11574370), and the Strategic Priority Research Program and Key Research Program of Frontier Sciences of the Chinese Academy of Sciences (Grant Nos. QYZDY-SSW-SLH001, QYZDY-SSW-SLH008, and XDB07020100).{These authors contributed equally to this work.

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摘要：

We synthesize a series of Mn substituted (Li, Fe)OHFeSe superconductor single crystals via a modified ion-exchange method, with the Mn concentration z (the atomic ratio of Mn:Se) ranging from 0 to 0.07. The distribution homogeneity of the Mn element incorporated into the lattice of (Li, Fe)OHFeSe is checked by combined measurements of high-angle-annular-dark-field (HAADF) imaging and electron energy-loss spectroscopy (EELS). Interestingly, we find that the superconducting transition temperature Tc and unit cell parameter c of the Mn-doped (Li, Fe)OHFeSe samples display similar V-shaped evolutions with the increasing dopant concentration z. We propose that, with increasing doping level, the Mn dopant first occupies the tetrahedral sites in the (Li, Fe)OH layers before starting to substitute the Fe element in the superconducting FeSe layers, which accounts for the V-shaped change in cell parameter c. The observed positive correlation between the Tc and lattice parameter c, regardless of the Mn doping level z, indicates that a larger interlayer separation, or a weaker interlayer coupling, is essential for the high-Tc superconductivity in (Li, Fe)OHFeSe. This agrees with our previous observations on powder, single crystal, and film samples of (Li, Fe)OHFeSe superconductors.

关键词: FeSe-based superconductors, Mn doping effect, correlation between superconductivity and interlayer separation

Abstract:

We synthesize a series of Mn substituted (Li, Fe)OHFeSe superconductor single crystals via a modified ion-exchange method, with the Mn concentration z (the atomic ratio of Mn:Se) ranging from 0 to 0.07. The distribution homogeneity of the Mn element incorporated into the lattice of (Li, Fe)OHFeSe is checked by combined measurements of high-angle-annular-dark-field (HAADF) imaging and electron energy-loss spectroscopy (EELS). Interestingly, we find that the superconducting transition temperature Tc and unit cell parameter c of the Mn-doped (Li, Fe)OHFeSe samples display similar V-shaped evolutions with the increasing dopant concentration z. We propose that, with increasing doping level, the Mn dopant first occupies the tetrahedral sites in the (Li, Fe)OH layers before starting to substitute the Fe element in the superconducting FeSe layers, which accounts for the V-shaped change in cell parameter c. The observed positive correlation between the Tc and lattice parameter c, regardless of the Mn doping level z, indicates that a larger interlayer separation, or a weaker interlayer coupling, is essential for the high-Tc superconductivity in (Li, Fe)OHFeSe. This agrees with our previous observations on powder, single crystal, and film samples of (Li, Fe)OHFeSe superconductors.

Key words: FeSe-based superconductors, Mn doping effect, correlation between superconductivity and interlayer separation

中图分类号:  (Pnictides and chalcogenides)

  • 74.70.Xa
82.30.Hk (Chemical exchanges (substitution, atom transfer, abstraction, disproportionation, and group exchange)) 74.25.-q (Properties of superconductors)