Phase Separation in La2CuO4+δSingle Crystals

Phase separation in La 2 CuO 4+δ single crystals was studied with electrical resistivity, magnetic susceptibility, X-ray and neutron diffraction measurements. The c-axis resistivity of an as-grown crystal has dropped from 265 K down to 190 K and shown a hysteretic behavior between 270 K and 190 K. From X-ray results, these anomalies have been attributed to the progress of phase separation. The antiferromagnetic transition was observed in the midst of the phase separation at 250 K using neutron and magnetic susceptibility measurements. On the other hand, the Neel point in an oxygen-reduced crystal was found to be higher than its onset of phase separation. Based on these results, an approximate phase diagram has been made. Moreover, we observed susceptibility difference between zero field and field-cooled conditions only under a low field, suggesting the magnetic-glass-like nature.

[1]  D. Johnston,et al.  Preparation, magnetization and electrical resistivity of electrochemically oxidized La2CuO4+δ single crystals , 1993 .

[2]  T. N. Fursova,et al.  Electron transitions at 0.1–0.6 eV and DC-conductivity in the semiconducting phase of La2CuO4+x single crystals , 1993 .

[3]  Chan,et al.  Copper oxide superconductors: A distinguishable thermodynamic state. , 1993, Physical review. B, Condensed matter.

[4]  J. Goodenough,et al.  Transport and magnetic properties of the superconducting La2CuO4+δ phases (0 < δ < 0.09) prepared by electrochemical oxidation , 1992 .

[5]  M. Kurisu,et al.  Two-step superconducting transition and anomalous pressure dependence of Tc in La2CuO4 , 1991 .

[6]  Y. Oda,et al.  New superconducting phases in La2CuO4+δ annealed in high- pressure oxygen gas , 1991 .

[7]  P. Midgley,et al.  Characteristics of mixed phase superconductivity in oxygenated La2CuO4+δ , 1991 .

[8]  Cox,et al.  Neutron and synchrotron x-ray powder-diffraction study of La2CuO4+ delta. , 1990, Physical review. B, Condensed matter.

[9]  S. Cheong,et al.  Two-phase structural refinement of La2CuO4.032 at 15 K , 1990 .

[10]  Fisk,et al.  Phase separation in a high-pressure-oxygenated La2CuO4+ delta crystal: Evidence from anisotropic electronic transport and magnetic susceptibility. , 1990, Physical review. B, Condensed matter.

[11]  Chen,et al.  Conductivity and Hall coefficient in La2CuO4+y near the insulator-metal transition. , 1989, Physical review. B, Condensed matter.

[12]  Fisk,et al.  Transport in crystalline La2CuO4+ delta : Enormous anomalies at TN for small hole doping. , 1989, Physical review. B, Condensed matter.

[13]  S. Cheong,et al.  THE CRYSTAL-STRUCTURE OF SUPERCONDUCTING LA2CUO4.032 BY NEUTRON-DIFFRACTION , 1989 .

[14]  S. Cheong,et al.  Superconductivity and Magnetism in the La_2CuO_4-Based Compounds , 1989 .

[15]  Venturini,et al.  Superconducting phase of La2CuO4-y: Superconducting composition resulting from phase separation. , 1988, Physical review. B, Condensed matter.

[16]  K. Oka,et al.  Phase Diagram of the La2O3-CuO System and Crystal Growth of (LaBa)2CuO4 , 1987 .