Granular superconductivity in powders of small graphite grains (several tens micrometers) is demonstrated after treatment with pure water. The temperature, magnetic field and time dependence the moment treated powder provides evidence for existence superconducting vortices some similarities to high-temperature granular oxides but even at temperatures above 300 K. Room temperature doped or its interfaces appears be possible. Detailed facts importance specialist readers are published as...

Transport properties of a few hundreds nanometers thick (in the graphene plane direction) lamellae highly oriented pyrolytic graphite (HOPG) have been investigated. Current-Voltage characteristics as well temperature dependence voltage at different fixed input currents provide evidence for Josephson-coupled superconducting regions embedded in internal two-dimensional interfaces, reaching zero resistance low enough temperatures. The overall behavior indicates existence with critical...

We have investigated exchange bias effects in bilayers composed by the antiferromagnetic o-YMnO$_3$ and ferromagnetic Co thin film means of SQUID magnetometry, magnetoresistance, anisotropic magnetoresistance planar Hall effect. The magnetization magnetotransport properties show pronounced asymmetries field axes hysteresis loops. Both parameters, $H_{E}(T)$ as well shift $M_E(T)$, vanish around N\'eel temperature $T_N \simeq 45$ K. that $M_E(T)$ is also measured a resistance having those...

We have studied the changes in ferromagnetic behavior of graphite powder and flakes after treatment with diluted sulphuric acid. show that this kind acid enhances substantially magnetization virgin micrometer size as well flakes. The anisotropic magnetoresistance amplitude at 300 K measured a thin flake reaches values comparable to polycrystalline cobalt.

We have studied the transport properties of transmission electron microscope (TEM) lamellae obtained from a pyrolytic graphite sample grade B (SPI-II) with electrical contacts at edges graphene layers. The temperature, magnetic field, input current dependence resistance as well current-voltage characteristic curves are compatible existence granular superconductivity below 5 K. TEM pictures reveal clear differences embedded interfaces to those existing in more ordered samples, which appear be...

We have studied the transport characteristics of TEM lamellae different widths obtained from a graphite sample with electrical contacts at edges embedded interfaces. The temperature dependence resistance, as well current-voltage characteristics, are compatible existence Josephson-coupled superconducting regions. transition which Josephson behavior sets in decreases decreasing interface width and vanishes for below 200 nm. This interface-size provides an explanation differences observed...

A theoretical study of the electronic properties InAsSb quantum dots (QDs) deposited on InP substrate is presented. Unstrained bulk materials present a direct gap between 0.1and 0.35eV suitable for mid-infrared emitters (2–5μm). However, strain and quantum-confinement effects may limit extension emission spectrum these nanostructures towards higher wavelengths. Various associations in barrier are considered. Among possible associations, InAs0.5Sb0.5∕GaAs0.5Sb0.5 QDs provide low-energy with...

Abstract We review the transport properties of different nanostructures produced by ion- and electron-beam deposition, as prepared well after certain treatments. In general, available literature indicates that are determined conduction processes typical for disordered metallic grains embedded in a carbon-rich matrix, including intergrain tunneling variable range hopping mechanisms. Special emphasis is given to superconducting behavior found Tungsten-Carbide that, field temperature range,...

Abstract Theoretical and experimental studies of the electronic properties InAs(Sb) quantum dots (QDs) grown on InP substrate are presented. Unstrained bulk InAsSb present direct gap between 0.1 eV to 0.35 suitable for mid infrared emitters (2‐5 µm). However, strain confinement effects may limit extension emission spectrum these nanostructures towards longer wavelengths. Various combinations barrier materials considered in simulations. Photoluminescence (PL) spectroscopy experiments...

We report local and non-local measurements in pin-hole dominated mesoscopic multigraphene spin-valves. Local spin-valve show spurious switching behavior resistance during magnetic field sweeping similar to the signal observed due spin injection into multigraphene. The has been explained terms of a Hall effect thickness irregularity tunnel barrier. appears large magnetostatic produced near roughness AlO(x) In our samples change remains negligibly small above 75 K. A strong might hinder...

A theoretical and experimental study of the electronic properties InAsSb quantum dots (QDs) grown on InP substrate is presented. Unstrained bulk presents a direct gap between 0.1 eV to 0.35 eV, suitable for mid infrared emitters (3–5 µm). However, strain confinement effects may limit extension emission spectrum these nanostructures towards longer wavelengths. Various combinations barrier materials are considered in simulations. First photoluminescence spectroscopy experiments molecular beam...

The electrical potential on the surface of ∼300 nm thick SiO(2) grown single-crystalline Si substrates has been characterized at ambient conditions using electric field microscopy. Our results show an inhomogeneous distribution with fluctuations up to ∼0.4 V within regions 1 µm. observed these usual dielectric holders graphene sheets should induce strong variations in charge densities and provide a simple explanation for some anomalous behaviors transport properties graphene.

The carrier density in tens of nanometers thick graphite samples (multi-layer-graphene, MLG) has been modified by applying a gate voltage ($V_g$) perpendicular to the graphene planes. Surface potential microscopy shows inhomogeneities ($n$) sample near surface region and under different values $V_g$ at room temperature. Transport measurements on MLG reveal that large enough applied electric field these regions undergo superconducting-like transition $T \lesssim 17$ K. A magnetic parallel or...

We have studied the magnetoresistive behaviour of permalloy clusters electrodeposited on silicon at temperatures ranging from 5 to 300 K. A giant (GMR) contribution observed low coercive fields (10 Oe) was attributed large clusters, and a broad peak Oe anisotropic (AMR). The GMR effect is due coherent spin injection cluster through Si matrix. This conduction mechanism also checked by depositing 2 nm Au layer top surface substrate with clusters.

Trying to dope graphite flakes we found that the magnetization of pure, several tens micrometers grain size powder and after a simple treatment with pure water shows clear reproducible granular superconducting behavior critical temperature above 300K. The observed magnetic characteristics as function temperature, field time, provide evidence for weakly coupled grains through Josephson interaction, revealing existence vortices.