Unconventional superconductivity in iron-based superconductors
Hai-Hu Wen
National Lab for Superconductivity, Institute of Physics, Chinese Academy of
Sciences, Beijing 100190, China
e-mail: hhwen@aphy.iphy.ac.cn
By using solid state reaction method we have synthesized both electron doped and
hole doped iron-based superconductors. For electron doped ones Re(O1-xFx)FeAs
(here Re=La, Nd and Sm), it is found that the normal state exhibits an anomaly in
resistivity and magnetic susceptibility at about 150 K in light doped samples, which
weakens by doping more electrons. This anomaly may be induced by the
antiferromagnetic order. Unconventional superconductivity was discovered by
measuring low temperature specific heat, lower critical field and point contact
tunneling spectrum, all illustrate a nodal gap behavior. In hole doped side (La1-
xSrx)OFeAs, this anomaly is weakened much slower and a very broad rounding occurs
in the resistivity vs. temperature curve, indicating the suppression to the AF
competing order in a different way compared with the electron doped side. The
normal state Hall effect clearly indicates a multiband feature in all samples. Possible
mechanism for the superconductivity is discussed.
In collaboration with:
Gang Mu, Xiyu Zhu, Lei Fang, Peng Cheng, Cong Ren, Lei Shan, Yonglei Wang,
Huiqian Luo, Zhaosheng Wang, Ying Jia
Some samples from Zhian Ren and Zhongxian Zhao are specially acknowledged.
References:
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H. H. Wen et al., Europhys. Lett. 82, 17009 (2008).
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X. Zhu et al., Condmat 0803. 1288
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G. Mu et al., Condmat 0803.0928. Chin. Phys. Lett.25, 2221(2008).
•
L. Shan et al., Condmat 0803. 2405
•
L. Fang et al., Condmat 0803.3978
•
P. Cheng et al., Condmat 0804.0835. Science in China G51, 719-722(2008).
•
C. Ren et al., Condmat 0804.1726

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