Charge ordering and long-range interactions in layered transition metal oxides

We study the competition between long-range and short-range interactions am ong holes within a continuum formulation of the spin density wave picture o f layered transition metal oxides. We focus on the problem of charge orderi ngs and the charge phase diagram. The main interactions are the long-range Coulomb interaction and a magnetic dipolar short-range interaction generate d by short-range antiferromagnetic fluctuations. Four different phases depe nding on the strength of the dipolar interaction and the density of holes e xist: Wigner crystal, diagonal stripes, horizontal-vertical stripes (loops) . and a glassy clumped phase. The effect of temperature, disorder, and latt ice effects on these phases are discussed. [S0031-9007(99)09355-2].