Curvature effect on the interaction between folded graphitic surface and silver clusters

Abstract

Evidence of curvature effects on the interaction and binding of silver clusters on folded graphitic surfaces has been shown from both experiment and theory. Density functional theory ͑DFT͒ calculations within the local density and generalized gradient approximations have been performed for the structural relaxation of both Ag and Ag 2 on curved surfaces, showing a crossover from chemical to physical behavior. Using Lennard-Jones potential to model the interaction between a single cluster and the graphite surface, evidence is found for the curvature effect on the binding of silver nanoparticles to folding graphitic surfaces. The theoretical results are compared to scanning electron microscopy and atomic force microscopy images of samples obtained from preformed silver cluster deposition on carboneous substrates exhibiting anisotropic pleat structures.

Reduced effect of impurities on the universal pairing scale in the cuprates

“…20,21 For the cuprates, most of the studies attributed a slow decrease of T * to the extended nature of the impurity potential 12,13,14 , but Monthoux and Pines 10 performed a numerical analysis of T * suppression in YBCO by non-magnetic Ni impurities and found that the initial slope of T * is quite small even when impurities are point-like scatterers. Very recently, Kemper et al 15 studied the effect of disorder using dynamical cluster approximation and quantum Monte Carlo, and found that ordinary pair-breaking by impurities is partly balanced by the impurity-induced enhancement of spin correlations which increases the pairing interaction mediated by spin fluctuations Our result agree with Kemper et al 15 and also Graser et al 14 in that the origin of the flattening of T * (Γ) are magnetic strong-correlation effects. At the same time, we found that, in the universal regime, T * very weakly depends on the spin correlation length ξ.…”

“…The effects of non-magnetic and magnetic impurities in superconductors with unconventional order parameters have been studied for high-T c cuprates, 10,11,12,13,14,15 non-cuprate superconductors, 16,17,18,19 and most recently for the pnictides. 20,21 For the cuprates, most of the studies attributed a slow decrease of T * to the extended nature of the impurity potential 12,13,14 , but Monthoux and Pines 10 performed a numerical analysis of T * suppression in YBCO by non-magnetic Ni impurities and found that the initial slope of T * is quite small even when impurities are point-like scatterers.…”

Metal-terminated graphene nanoribbons

“…Most of the theoretical studies on GNRs for spintron-ics applications so far only address ribbons with hydrogen terminations [14][15][16] . Recent experiments have shown that graphitic surface curvature can be used as constraint and guide in which metal clusters aggregate to form linear islands 18,19 . The presence of metal atoms adsorbed on the graphene [20][21][22][23] or GNR 24 changes its electronic and magnetic properties and thus is certainly of great interest in physics.…”

Dimensionality transition in submonolayer growth on carbon nanotubes

“…A detailed investigation of the simulations shows that the scaling exponents z and χ indicate a transition from 2D to 1D when confinement is increased and allows us to identify the critical diameter L 2D below which the system is affected by confinement. Other substrates, such as top facets of graphite pleats where Ag clusters are confined, could also be good candidates for the observation of the dimensionality transition in submonolayer growth [22,23].…”

“…The majority of experiments has been performed on atomically flat crystal facets, corresponding to the 2D case [9,11]. Experiments have also been performed in the 1D case, a prominent example being adsorption on linear defects, such as atoms or fullerenes on atomic-step edges [4,[17][18][19][20][21], or nanoparticles on graphite pleats [22,23]. In addition, some models have discussed the interplay between 2D and 1D effects in submonolayer growth due to the presence of atomic steps on facetted substrates [24].…”