[16p-D209-1~14] 11.1 Fundamental properties

[16p-D209-6] Superconductivity in Pr₂Ba₄Cu₇O_15-δ IV: Cu Nuclear-Spin Evidence of Chain-Driven Superconductivity

Shunsaku Nakagawa¹, Sotaro Nishioka², Mitsuharu Yashima¹, Hidekazu Mukuda³, Mamoru Yogi², Kosuke Ikeda⁴, 〇Susumu Sasaki⁴, Jun-ichi Shimoyama⁵ (1.Osaka Univ., 2.NIMS, 3.Ryukyus Univ., 4.Niigata Univ., 5.Aoyama-Gakuin Univ.)

Keywords:superconductor, cuprate, double chains

Pr₂Ba₄Cu₇O_17-δ (Pr247) has a hybrid structure composed of Pr123 and Pr124. If well-prepared, Pr247 was suggested to be superconducting, but the volume fraction was less than 10%. Recently, we have succeeded in synthesizing Pr247 of 100% superconducting fraction. In addition, through our Cu-NQR frequency spectra, we clarified that the CuO₂ planes are in an insulating and antiferromagnetic state. Here we report from Cu-NQR spin-lattice relaxation rate that superconducting gap clearly opens up in the Cu₂O₂ double chains. This indicates that, unlike all the other cuprates, the superconductivity is driven not by the planes but by the double chains.