中国物理B ›› 2012, Vol. 21 ›› Issue (7): 77403-077403.doi: 10.1088/1674-1056/21/7/077403

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Evolution of the 251 cm-1 infrared phonon mode with temperature in Ba0.6K0.4Fe2As2

戴耀民a b, 许兵a b, 沈冰a, 肖宏a, Lobo R. P. S. Mb, 邱祥冈a   

  1. a Beijing National Laboratory for Condensed Matter Physics, National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
    b LPEM, ESPCI-ParisTech, CNRS, UPMC, 10 rue Vauquelin, F-75231 Paris Cedex 5, France
  • 收稿日期:2012-03-12 修回日期:2012-03-23 出版日期:2012-06-01 发布日期:2012-06-01
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 11104335 and 91121004), the National Basic Research Program of China (Grant Nos. 2011CBA00107, 2012CB821400, and 2009CB929102), and the ANR, France (Grant No. BLAN07-1-183876 GAPSUPRA).

Evolution of the 251 cm-1 infrared phonon mode with temperature in Ba0.6K0.4Fe2As2

Dai Yao-Min(戴耀民)a)b), Xu Bing(许兵)a)b), Shen Bing(沈冰)a), Xiao Hong(肖宏)a), Lobo R. P. S. Mb), and Qiu Xiang-Gang(邱祥冈)a)†   

  1. a Beijing National Laboratory for Condensed Matter Physics, National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China;
    b LPEM, ESPCI-ParisTech, CNRS, UPMC, 10 rue Vauquelin, F-75231 Paris Cedex 5, France
  • Received:2012-03-12 Revised:2012-03-23 Online:2012-06-01 Published:2012-06-01
  • Contact: Qiu Xiang-Gang E-mail:xgqiu@iphy.ac.cn
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos. 11104335 and 91121004), the National Basic Research Program of China (Grant Nos. 2011CBA00107, 2012CB821400, and 2009CB929102), and the ANR, France (Grant No. BLAN07-1-183876 GAPSUPRA).

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摘要： The far-infrared optical reflectivity of optimally doped Ba1-xKxFe2As2 (x = 0.4) single crystal is measured from room temperature down to 4 K. We study the temperature dependence of the in-plane infrared-active phonon at 251 cm-1. This phonon exhibits a symmetric line shape in the optical conductivity, suggesting that the coupling between the phonon and the electronic background is weak. Upon cooling down, the frequency of this phonon continuously increases, following the conventional temperature dependence expected in the absence of a structural or magnetic transition. The intensity of this phonon is temperature independent within the measurement accuracy. These observations indicate that the structural and magnetic phase transition might be completely suppressed by the chemical doping in the optimally doped Ba0.6K0.4Fe2As2 compound.

关键词: iron-based superconductor, phonon mode, infrared spectroscopy

Abstract: The far-infrared optical reflectivity of optimally doped Ba1-xKxFe2As2 (x = 0.4) single crystal is measured from room temperature down to 4 K. We study the temperature dependence of the in-plane infrared-active phonon at 251 cm-1. This phonon exhibits a symmetric line shape in the optical conductivity, suggesting that the coupling between the phonon and the electronic background is weak. Upon cooling down, the frequency of this phonon continuously increases, following the conventional temperature dependence expected in the absence of a structural or magnetic transition. The intensity of this phonon is temperature independent within the measurement accuracy. These observations indicate that the structural and magnetic phase transition might be completely suppressed by the chemical doping in the optimally doped Ba0.6K0.4Fe2As2 compound.

Key words: iron-based superconductor, phonon mode, infrared spectroscopy

中图分类号:  (Pnictides and chalcogenides)

  • 74.70.Xa
63.20.-e (Phonons in crystal lattices) 78.30.-j (Infrared and Raman spectra)