Nanoscale coherent intergrowthlike defects in a crystal of La1.9Ca1.1Cu2O6+delta made superconducting by high-pressure oxygen annealing

作者：Hu Hefei^*; Zhu Yimei; Shi Xiaoya; Li Qiang; Zhong Ruidan; Schneeloch John A; Gu Genda; Tranquada John M; Billinge Simon J L

来源：Physical Review B, 2014, 90(13): 134518.

DOI：10.1103/PhysRevB.90.134518

Superconductivity with T-c = 53.5 K has been induced in a large La1.9Ca1.1Cu2O6 (La-2126) single crystal by annealing in a high partial pressure of oxygen at 1200 degrees C. Using transmission electron microscopy techniques, we show that a secondary Ca-doped La2CuO4 (La-214) phase, not present in the as-grown crystal, appears as a coherent intergrowthlike defect as a consequence of the annealing. A corresponding secondary superconducting transition near 13 K is evident in the magnetization measurement. Electron energy-loss spectroscopy reveals a pre-edge peak at the O-K edge in the superconducting La-2126 phase, which is absent in the as-grown crystal, confirming the hole doping by interstitial oxygen.

• 出版日期2014-10-28