Effect of low-temperature oxygen ordering on the properties of RBa2Cu3O6+x (R = Y, Tm, Lu) single crystals

The effect of oxygen ordering on the normal-state and superconducting properties of RBa2Cu3O6+x (R = Y, Tm, Lu) single crystals was studied over a wide range of oxygen stoichiometries (0.29 less than or equal to x less than or equal to 0.92). At room temperature, oxygen ordering was found to cause a significant (by up to 100 K) decrease in the Neel temperature for all antiferromagnetic compositions (x < 0.4) and an increase in the superconducting transition temperature for superconducting materials (0.4 < x < 0.9). A low-temperature phase diagram caking into account oxygen ordering was constructed, and the role of particular structural components is discussed. Analysis of correlations between the normal-state and superconducting properties indicates that the superconducting transition temperature is affected not only by the carrier concentration in the CuO2 planes but also by interlayer coupling.