Abstract Body

In cuprate superconductors, it is recognized that the layered structure comprising multiple CuO₂ layers is essential for achieving T_c> 100 K [1]. Multilayered cuprates usually contain Ca layers between CuO₂ layers. Recently, we have developed new double layered superconductors, such as Sr₂SrCu₂O_4+yO_2-y (Sr-0212-F), (B,C)Sr₂SrCu₂O₇ ((B,C)-Sr-1212), TlSr₂SrCu₂O_y (Tl-Sr-1212), and HgSr₂SrCu₂O_y (Hg-Sr-1212), using high-pressure and post-annealed synthesis methods. These compounds are composed of Sr layers instead of Ca layers [2,3] and their T_c values are comparable to those of Ca-containing counterparts. We evaluated the superconducting parameters such as critical current density of these Ca-free cuprate superconductors. We found that the Hg-Sr-1212 based cuprates exhibit the J_c value exceeds 10⁶Acm^-2 at low temperatures and under magnetic fields J_c and B_irr are improved through the partial substitution of Hg with Mo or Re [4]. (Hg, Re)Sr₂SrCu₂O_y possesses the irreversibility line as high as that of the reported triple-layered (Hg, Re)Sr₂Ca₂Cu₃O_y. The enhanced J_c and B_irr properties likely come from a decrease in the thickness of the blocking layer.

References

[1] e.g., H. Mukuda, et al., J. Phys. Soc. Jpn. 81, 011008 (2012).
[2] H. Ninomiya, K. Kawashima, et al., Commun. Mater. 2, 13 (2021).
[3] H. Ninomiya, K. Kawashima, et al., Chem. Mater. 33, 9690 (2021).
[4] H. Ninomiya, K. Kawashima et al., submitted.

Acknowledgment

We thank I. Hase and H. Kito for fruitful discussions.