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arXiv · 0804.4290

Thorium-doping induced superconductivity up to 56 K in Gd1-xThxFeAsO

Cao Wang·Linjun Li·Shun Chi·Zengwei Zhu·Zhi Ren·Yuke Li·Yuetao Wang·Xiao Lin·Yongkang Luo·Shuai Jiang·Xiangfan Xu·Guanghan Cao·Zhu'an Xu
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Abstract

Following the discovery of superconductivity in an iron-based arsenide LaO1-xFxFeAs with a superconducting transition temperature (Tc) of 26 K[1], Tc was pushed up surprisingly to above 40 K by either applying pressure[2] or replacing La with Sm[3], Ce[4], Nd[5] and Pr[6]. The maximum Tc has climbed to 55 K, observed in SmO1-xFxFeAs[7, 8] and SmFeAsO1-x[9]. The value of Tc was found to increase with decreasing lattice parameters in LnFeAsO1-xFx (Ln stands for the lanthanide elements) at an apparently optimal doping level. However, the F- doping in GdFeAsO is particularly difficult[10,11] due to the lattice mismatch between the Gd2O2 layers and Fe2As2 layers. Here we report observation of superconductivity with Tc as high as 56 K by the Th4+ substitution for Gd3+ in GdFeAsO. The incorporation of relatively large Th4+ ions relaxes the lattice mismatch, hence induces the high temperature superconductivity.

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Cao Wang, Linjun Li, Shun Chi, Zengwei Zhu, Zhi Ren, Yuke Li, Yuetao Wang, Xiao Lin, Yongkang Luo, Shuai Jiang, Xiangfan Xu, Guanghan Cao, Zhu'an Xu. 2008-04-28. Thorium-doping induced superconductivity up to 56 K in Gd1-xThxFeAsO. https://doi.org/10.1209/0295-5075/83/67006

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