Dynamics of the phase separation of LA_2CUO_(4+X) single crystals

摘要

The process of phase separation (PS) in the system La_2Cu_O(4+x) was first, observed in [1] and then investigated in detail by neutrom diffraction measurements in [2], where a phase diagram for this compounds was obtained. According to the diffraction data, in La_2CuO_(4+x), a temperature reversilbe separation into two nearly identical by lattice parameter orthorhombic phases takes place [1-3]. The oxygen-rich (x chemical bounds 0.06) metallic phase becomes superconducting below T_c chemical bounds 38K and the second insulating phase (x<0.01) is antiferromagnetic (AFM). The phase domain of oxygen-rich region has typical dimensions of about 1000 angstroms according to the neutron diffraction data. From the neutron diffraction data on plycrystalline electrochemically oxidized La_2CuO_(4+x), miscibility gap limits were found to be x chemical bounds 0.01 and x chemical bounds 0.06 [2,4,5]. The temperature of phase separation varies from 250K to 415K with extra oxygen contents inside the miscibility gap.