title: Finding the elusive sliding phase in the superfluid-normal phase transition smeared by c-axis disorder.
abstract: We consider a stack of weakly Josephson coupled superfluid layers with c-axis disorder in the form of random superfluid stiffnesses and vortex fugacities in each layer as well as random interlayer coupling strengths. In the absence of disorder this system has a 3D XY type superfluid-normal phase transition as a function of temperature. We develop a functional renormalization group to treat the effects of disorder, and demonstrate that the disorder results in the smearing of the superfluid-normal phase transition via the formation of a Griffiths phase. Remarkably, in the Griffiths phase, the emergent power-law distribution of the interlayer couplings gives rise to a sliding Griffiths superfluid, with a finite stiffness in the a-b direction along the layers, and a vanishing stiffness perpendicular to it.
authors.affiliation: Physics Department, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138, USA.
authors.forename: David
authors.initials: D
authors.lastname: Pekker
authors.forename: Gil
authors.initials: G
authors.lastname: Refael
authors.forename: Eugene
authors.initials: E
authors.lastname: Demler