title: Disorder-driven critical behavior of periodic elastic media in a crystal potential.
abstract: A lattice model of a three-dimensional periodic elastic medium at zero temperature is studied with exact combinatorial optimization methods. A competition between pinning of the elastic medium, representing magnetic flux lines in a superconductor or charge density waves in a crystal, by randomly distributed impurities and a periodic lattice potential gives rise to a continuous roughening transition from a flat to a rough phase. A finite size scaling analysis yields the critical exponents nu approximately 1.3, beta approximately 0.05, gamma/nu approximately 2.9 that are universal with respect to the periodicity of the lattice potential. The small order parameter exponent is reminiscent of the random field Ising critical behavior in 3D.
authors.affiliation: Theoretische Physik, Universität des Saarlandes, 66041 Saarbrücken, Germany.
authors.forename: J D
authors.initials: JD
authors.lastname: Noh
authors.forename: H
authors.initials: H
authors.lastname: Rieger