[23p-D215-1~16] 11.1 Fundamental properties

[23p-D215-10] Superconductivity in Pr₂Ba₄Cu₇O_15-δ III: Cu Nuclear-Spin Evidence of Superconductivity in the Double Chains

Sotaro Nishioka¹, Shunsaku Nakagawa¹, Mitsuharu Yashima¹, Hidekazu Mukuda¹, Mamoru Yogi², Kosuke Ikeda³, Dwi Prananto³, 〇Susumu Sasaki^3,4, Jun-ichi Shimoyama⁵ (1.Osaka Univ, 2.Univ. Ryukyus, 3.Niigata Univ, 4.AMED, 5.Aoyama-Gakuin Univ)

Keywords:cuprate superconductor, nuclear spin, double-chain driven superconductivity

In contrast to the “Pr-issue” that neither Pr123 nor Pr124 shows superconductivity (SC), we have observed 100%-fraction of SC in an oxygen-reduced Pr247 which has a hybrid structure that Pr247 = Pr123 + Pr124. Last time, we have reported that Cu nuclear-spin signals from the CuO₂ planes observed at 300K are completely wiped out at 2K. Instead, the plane signals at 2K are observed at higher frequencies. This indicates that, despite the bulk SC, the CuO₂ planes in Pr247 are found to be in an insulating and antiferromagnetically ordered state. This time, we show that the spin-lattice relaxation rate of the Cu nuclear spins in the double chains substantially decrease, indicating the SC in the double chains. We also discuss the electronic state of the single chains.