1/8 Anomaly Induced by the Substitution of Dy in Underdoped Bi 2 Sr 2 Ca 1− x Dy x Cu 2 O 8+ δ

An anomalous “dip” feature near the hole concentration of p ∼ 1/8 on the T c − p curve of Bi2Sr2 Ca1−x Dy x Cu2O8+δ (Dy-Bi2212) was reported. Dy-Bi2212 with p∼ 1/8 exhibited a “checkerboard charge order” with a wave vector ∼ 0.3 r.l.u., and well-defined coherent peaks were not observed in the quasiparticle tunneling spectra of this material, obtained from scanning tunneling microscopy/spectroscopy (STM/STS) experiments. The dip of the T c−p curve induced by the substitution of Dy in Bi2212 was similar to that observed in Zn-doped Bi2212 (Akoshima et al., Phys. Rev. B 57, 7491 1998), suggesting that the suppression of T c near p∼ 1/8 in Dy-Bi2212 is related to the pinning of the charge order.