P. Vairus et al., SUPERCONDUCTING CRITICAL-TEMPERATURE, OXYGEN ORDERING AND DEVILS STAIRCASE IN YBA2CU3O6+X, Physica. C, Superconductivity, 235, 1994, pp. 301-302
Using the appropriate extension of the three-band Hubbard model to des
cribe the basal CuO2+x subsystem of YBa2Cu3O6+x for a certain region o
f parameters we obtain: a) the number of holes n(H) in the superconduc
ting planes and T-c as a function of x have a plateau, b) using a stru
ctural model to include the effect of interatomic O-O repulsions, ther
e is a transition from structures without first or second nearest-neig
hbor O atoms (RS) to order in chains (CS) at x similar to 0.45 for inc
reasing x. We also study the structural model for values of x for whic
h the CS are stable.