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arXiv · 1604.04964

Superconductivity in undoped CaFe2As2 single crystals

Dong-Yun Chen·Jia Yu·Bin-Bin Ruan·Qi Guo·Lei Zhang·Qing-Ge Mu·Xiao-Chuan Wang·Bo-Jin Pan·Gen-Fu Chen·Zhi-An Ren
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Abstract

Single crystals of undoped CaFe2As2 were grown by a FeAs self-flux method, and the crystals were quenched in ice-water rapidly after high temperature growth. The quenched crystal undergoes a collapsed tetragonal structural phase transition around 80 K revealed by the temperature dependent X-ray diffraction measurements. Superconductivity below 25 K was observed in the collapsed phase by resistivity and magnetization measurements. The isothermal magnetization curve measured at 2 K indicates that this is a typical type-II superconductor. For comparison, we systematically characterized the properties of the furnace cooled, quenched, and post-annealed single crystals, and found strong internal crystallographic strain existing in the quenched samples, which is the key for the occurrence of superconductivity in the undoped CaFe2As2 single crystals.

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Dong-Yun Chen, Jia Yu, Bin-Bin Ruan, Qi Guo, Lei Zhang, Qing-Ge Mu, Xiao-Chuan Wang, Bo-Jin Pan, Gen-Fu Chen, Zhi-An Ren. 2016-04-18. Superconductivity in undoped CaFe2As2 single crystals. https://arxiv.org/abs/1604.04964

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