Phase diagram and critical properties of oxygen ordering in YBa2Cu3Oz

✍ Scribed by N.C. Bartelt; T.L. Einstein; L.T. Wille

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 140 KB
• Volume: 162-164
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(89)90498-x

✦ Synopsis

Using transfer-matrix finite-size scaling, we reinvestigate a square lattice-gas model Hamiltonian to describe the order-disorder transition in the Cu-O basal plane of YBa2Cu3Oz. The model contains strong nearest-neighbor repulsions and diagonal (2nd neighbor) interactions that alternate in sign. These interactions ensure the stability (at zero temperature) of two experimentally observed structures: a single-cell orthorhombic phase near z = 7 and a double-cell orthorhombic phase near z = 6.5. Critical properties can be understood by recasting the model as an Ashkin-Teller model; numerical results are consistent with this picture.