Peiwen Gao, Liling Sun, Ni Ni, Jing Guo, Qi Wu, Chao Zhang, Dachun Gu, Ke Yang, Sheng Jiang, Robert Joseph Cava, Zhongxian Zhao
The Ca10(PtnAs8)(Fe2As2)5 (n=3,4) compounds are a new type of iron pnictide superconductor whose structures consist of stacking Ca-PtnAs8-Ca-Fe2As2 layers in a unit cell. When n=3 (the 10-3-8 phase), the undoped compound is an antiferromagnetic (AFM) semiconductor, while, when n=4 (the 10-4-8 phase), the undoped compound is a superconductor (Tc=26K), a difference that has been attributed to the electronic character of the PtnAs8 intermediary layers. Here we report high-pressure studies on 10-3-8 and 10-4-8, using a combination of in-situ resistance, magnetic susceptibility, Hall coefficient and X-ray diffraction measurements. We find that the AFM order in undoped 10-3-8 is suppressed completely at 3.5 GPa and that superconductivity then appears in the 3.5-7 GPa pressure range with a classic dome-like behavior. In contrast, Tc in the 10-4-8 phase displays a monotonic decrease with increasing pressure. Our results allow for the establishment of a unique correspondence between pressure-induced and doping-induced superconductivity in the high-Tc iron pnictides, and also points the way to an effective strategy for finding new high-Tc superconductors.
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http://arxiv.org/abs/1301.2863
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