title: Depinning transition at the upper critical dimension.
abstract: We study the effect of quenched random field disorder on a driven elastic interface close to the depinning transition at the upper critical dimension d(c)=4 using the functional renormalization group. We have found that the displacement correlation function behaves with distance x as (ln xLambda(0))(2/3) for large x. Slightly above the depinning transition the force-velocity characteristics are described by the equation v approximately f|ln f|(2/9), while the correlation length behaves as L(v) approximately f(-1/2)|ln f|(1/6), where f=F/F(c)-1 is the reduced driving force.
authors.affiliation: Fachbereich Physik, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany.
authors.forename: Andrei A
authors.initials: AA
authors.lastname: Fedorenko
authors.forename: Semjon
authors.initials: S
authors.lastname: Stepanow