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Intrinsic Josephson junctions in the iron-based multi-band superconductor (V2Sr4O6)Fe2As2

Nature Physics volume 10, pages 644–647 (2014)Cite this article

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Abstract

In layered superconductors, Josephson junctions may be formed within the unit cell1,2,3 as a result of sufficiently low inter-layer coupling. These intrinsic Josephson junction (iJJ) systems4 have attracted considerable interest for their application potential in quantum computing as well as efficient sources of THz radiation, closing the famous ‘THz gap’5. So far, iJJ have been demonstrated in single-band, copper-based high-Tc superconductors, mainly in Bi–Sr–Ca–Cu–O (refs 6, 7, 8). Here we report clear experimental evidence for iJJ behaviour in the iron-based superconductor (V2Sr4O6)Fe2As2. The intrinsic junctions are identified by periodic oscillations of the flux-flow voltage on increasing a well-aligned in-plane magnetic field9. The periodicity is explained by commensurability effects between the Josephson vortex lattice and the crystal structure, which is a hallmark signature of Josephson vortices confined into iJJ stacks10,11. This finding adds the pnictide (V2Sr4O6)Fe2As2 to the copper-based iJJ materials of interest for Josephson junction applications. In particular, novel devices based on multi-band Josephson coupling may be realized.

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Figure 1: The intrinsic Josephson junction pnictide (V2Sr4O6)Fe2As2.
Figure 2: Josephson vortex commensurability oscillations.
Figure 3: Comparison against copper-based intrinsic Josephson junction compounds.

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Acknowledgements

We thank G. Blatter and D. Geshkenbein for stimulating discussions. FIB work was supported by EMEZ and ScopeM at ETH Zürich. Work in Nanjing was supported by the Ministry of Science and Technology of China (973 Projects: No. 2011CBA00102, No. 2010CB923002).

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Author notes

  1. Peng Cheng

    Present address: Present address: Department of Physics, Renmin University of China, Beijing 100872, China.,

Authors and Affiliations

  1. Physics of New Materials, Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland

    Philip J. W. Moll & Bertram Batlogg

  2. National Laboratory of Solid State Microstructures and Department of Physics, Center for Superconducting Physics and Materials, Nanjing University, Nanjing 210093, China

    Xiyu Zhu & Hai-Hu Wen

  3. National Laboratory for Superconductivity, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China

    Peng Cheng & Hai-Hu Wen

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  1. Philip J. W. Moll
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  2. Xiyu Zhu
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Contributions

P.J.W.M. designed the experiment, FIB-structured the crystals and performed the measurements. Single crystals were grown and analysed by X.Z., P.C. and H-H.W. P.J.W.M. and B.B. analysed the data and wrote the manuscript.

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Correspondence to Philip J. W. Moll.

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Moll, P., Zhu, X., Cheng, P. et al. Intrinsic Josephson junctions in the iron-based multi-band superconductor (V2Sr4O6)Fe2As2. Nature Phys 10, 644–647 (2014). https://doi.org/10.1038/nphys3034

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