title: Two-dimensional charge order in layered 2-1-4 perovskite oxides.
abstract: Monte Carlo simulations are performed on the three-dimensional (3D) Ising model with the 2-1-4 layered perovskite structure as a minimal model for checkerboard charge ordering phenomena in layered perovskite oxides. Because of the interlayer frustration, only 2D long-range order emerges with a finite correlation length along the c axis. Critical exponents of the transition change continuously as a function of the interlayer coupling constant. The interlayer long-range Coulomb interaction decays exponentially and is negligible even between the second-neighbor layers. Instead, monoclinic distortion of a tetragonal unit cell lifts the macroscopic degeneracy to induce a 3D charge ordering. The dimensionality of the charge order in La0.5Sr1.5MnO4 is discussed from this viewpoint.
authors.affiliation: Tokura Spin SuperStructure Project, ERATO, Japan Science and Technology Corporation, Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Shigeki
authors.initials: S
authors.lastname: Onoda
authors.forename: Yukitoshi
authors.initials: Y
authors.lastname: Motome
authors.forename: Naoto
authors.initials: N
authors.lastname: Nagaosa