Oxygen ordering and chain formation in YBa2Cu3Oz

A distinctive aspect of the thermodynamic properties of YBa2Cu3O2 is the basal-plane oxygen ordering which leads to the formation of Cu-O chains and the development of orthorhombic phases. Theoretically, this phenomenon may be explained in terms of an Ising Hamiltonian with two types of second-neighbor interactions (ASYNNNI model). This symmetry breaking and ground-state degeneracy lead to kinetically arrested multi-domain structures. This paper reports new simulation results for these mesoscopic features, with specific emphasis on the effects of dopants, elastic deformation, and possible structural phase separation.