Dirac Electrons with Molecular Relaxation Time at Electrochemical Interface between Graphene and Water.

The time dynamics of charge accumulation at the electrochemical interface between graphene and water is important for supercapacitors, batteries, and chemical and biological sensors. By using impedance spectroscopy, we have found that measured capacitance (C) at this interface with the gate voltage V ≈ 0.1 V follows approximate laws C~T and C~T (T is V period) in frequency ranges (1000-50,000) Hz and (0.

General Capacitance Upper Limit and Its Manifestation for Aqueous Graphene Interfaces.

Double-layer capacitance (C) is essential for chemical and biological sensors and capacitor applications. The correct formula for C is a controversial subject for practically useful graphene interfaces with water, aqueous solutions, and other liquids. We have developed a model of C, considering the capacitance of a charge accumulation layer (C) and capacitance (C) of a capacitance-limiting edge region with negligible electric susceptibility and conductivity between this layer and the capacitor electrode.

Influence of Substrate Microstructure on the Transport Properties of CVD-Graphene.

We report the study of electrical transport in few-layered CVD-graphene located on nanostructured surfaces in view of its potential application as a transparent contact to optoelectronic devices. Two specific surfaces with a different characteristic feature scale are analyzed: semiconductor micropyramids covered with SiO2 layer and opal structures composed of SiO2 nanospheres. Scanning tunneling microscopy (STM) and scanning electron microscopy (SEM), as well as Raman spectroscopy, have been used to determine graphene/substrate surface profile.

Anomalous expansion of the copper-apical-oxygen distance in superconducting cuprate bilayers.

We have introduced an improved x-ray phase-retrieval method with unprecedented speed of convergence and precision, and used it to determine with sub-Angstrom resolution the complete atomic structure of epitaxial La(2-x)Sr(x)CuO(4) ultrathin films. We focus on superconducting heterostructures built from constituent materials that are not superconducting in bulk samples. Single-phase metallic or superconducting films are also studied for comparison.

A magnetic field sensitive interfacial metallic state in a crystalline insulator.

We report strongly magnetic field dependent transport in crystalline strontium titanate at the interface with an ion beam treated nanolayer. Microscopy shows that this interface is atomically sharp. The results obtained suggest a chemical potential driven transfer of high mobility electrons through the interface into the crystal.

Highly conductive nanolayers on strontium titanate produced by preferential ion-beam etching.

Developing fabrication methods for electronically active nanostructures is an important challenge of modern science and technology. Fabrication efforts for crystalline materials have been focused on state-of-the-art epitaxial growth techniques. These techniques are based on deposition of precisely controlled combinations of various materials on a heated substrate.