R.R. da Silva

Reentrant Metallic Behavior of Graphite in the Quantum Limit

Magnetotransport measurements performed on several well-characterized highly oriented pyrolitic graphite and single crystalline Kish graphite samples reveal a reentrant metallic behavior in the basal-plane resistance at high magnetic fields, when only the lowest Landau levels are occupied. The results suggest that the quantum Hall effect and Landau-level-quantization-induced superconducting correlations are relevant to understand the metalliclike state(s) in graphite in the quantum limit.

Magnetism in photopolymerized fullerenes

Abstract The phototransformation of bulk C60 and laser- and electron-beam treatment of C60 films in air changes their magnetic properties. Nonlinear magnetization is observed only for samples irradiated in the presence of oxygen, while, in the case of pressure-polymerized C60, oxygen adversely affects the magnetic properties. The contrasting roles of oxygen in these processes are discussed. Magnetic force microscopy shows that laser- and electron-beam irradiation of fullerene films produces magnetic images which are highly correlated with the topographic images.

Local ferromagnetism in microporous carbon with the structural regularity of zeolite Y

Magnetization M(H,T) measurements have been performed on microporous carbon (MC) with a three-dimensional nanoarray structure corresponding to that of a zeolite Y supercage. The obtained results unambiguously demonstrate the occurrence of high-temperature ferromagnetism in MC, probably originating from a topological disorder associated with curved graphene sheets. The results provide evidence that the ferromagnetic behavior of MC is governed by isolated clusters in a broad temperature range, and suggest the occurrence of percolative-type transition with the temperature lowering. A comparative analysis of the results obtained on MC and related materials is given.

Universal magnetic-field-driven metal-insulator-metal transformations in graphite and bismuth

Applied magnetic field induces metal-insulator and reentrant insulator-metal transitions in both graphite and rhombohedral bismuth. The corresponding transition boundaries plotted on the magnetic field\char22{}temperature

Negative c-axis magnetoresistance in graphite

(B\text{\ensuremath{-}}T)

Anomalous Hall effect in graphite

plane nearly coincide for these semimetals and can be best described by power laws

Thermomagnetic Flux-Jump Instabilities and Second Magnetization Peak in Bi2Sr2CaCu2O8 High-Tc Superconducting Crystals

T\ensuremath{\sim}{(B\text{\ensuremath{-}}{B}_{c})}^{\ensuremath{\kappa}}

IP over WDM Module for the NS-2 Simulator

, where

18 – Ferromagnetic and Superconducting Instabilities in Graphite

{B}_{c}

Vortex lattice in Bi2Sr2CaCu2O8 well above the first-order phase transition boundary

is a critical field at