Field emission of electrons from individually mounted carbon nanotubes has been found to be dramatically enhanced when the nanotube tips are opened by laser evaporation or oxidative etching. Emission currents of 0.1 to 1 microampere were readily obtained at room temperature with bias voltages of less than 80 volts. The emitting structures are concluded to be linear chains of carbon atoms, Cn, (n = 10 to 100), pulled out from the open edges of the graphene wall layers of the nanotube by the force of the electric field, in a process that resembles unraveling the sleeve of a sweater.

http://science.sciencemag.org/content/sci/269/5230/1550.full.pdf

Unraveling Nanotubes: Field Emission from an Atomic Wire

We review studies of the electromagnetic response of various classes of correlated electron materials including transition metal oxides, organic and molecular conductors, intermetallic compounds with $d$- and $f$-electrons as well as magnetic semiconductors. Optical inquiry into correlations in all these diverse systems is enabled by experimental access to the fundamental characteristics of an ensemble of electrons including their self-energy and kinetic energy. Steady-state spectroscopy carried out over a broad range of frequencies from microwaves to UV light and fast optics time-resolved techniques provide complimentary prospectives on correlations. Because the theoretical understanding of strong correlations is still evolving, the review is focused on the analysis of the universal trends that are emerging out of a large body of experimental data augmented where possible with insights from numerical studies.

/pdf/electrodynamics-of-correlated-electron-materials-2qg1x9aaaz.pdf

Electrodynamics of correlated electron materials

We introduce the development of conductive organic molecular assemblies including organic metals, superconductors, single component conductors, conductive films, and conductive liquids, particularl...

Development of Conductive Organic Molecular Assemblies: Organic Metals, Superconductors, and Exotic Functional Materials

https://repository.library.northeastern.edu/files/neu:331186/fulltext.pdf

A survey of the Van Hove scenario for high-tc superconductivity with special emphasis on pseudogaps and striped phases

Recent studies of charge-transfer salts of the ion bis(ethylenedithio)tetrathiafulvalene (BEDT-TTF or ET) are reviewed, focusing in particular on experimental techniques which involve high magnetic fields and on data obtained since 1996. Novel experimental techniques developed in the past few years, including angle-dependent magnetoresistance oscillations, periodic orbit resonances and Fermi-surface traversal resonances are described in detail; briefer descriptions of more traditional techniques such as the Shubnikov-de Haas effect are also included. The applications of these techniques to the ?, ?, ? and ?'' BEDT-TTF salts is described. Theoretical developments related to the experimental data are also mentioned.

https://iopscience.iop.org/article/10.1088/0034-4885/63/8/201/pdf

Studies of quasi-two-dimensional organic conductors based on BEDT-TTF using high magnetic fields

We propose a Fermi-surface topological effect to describe the magnetotransport anisotropy of a quasi-one-dimensional electron system. When the magnetic field is parallel to one of the interchain lattice vectors having finite effective transfer integrals, the electrons can drift in the field direction with an open-orbit trajectory, causing a resonant increase of the longitudinal conduction. This model is applied to the magnetoresistance anisotropy of the quasi-one-dimensional organic superconductor (tetramethyltetraselenafulvalene${)}_{2}$X.

Resonance effect in magnetotransport anisotropy of quasi-one-dimensional conductors

One‐Dimensional Conductors

We theoretically and experimentally study a new type of angular effect of magnetoresistance in quasi-one-dimensional (Q1D) conductors. It is a kink structure on the angular dependence of interlayer magnetoresistance when the magnetic field is rotated in the most conducting plane. This effect originates from the appearance or vanishing of closed orbits on the sheetlike Fermi surface. This is ``the third angular effect'' in the Q1D conductors following the Lebed resonance and the Danner-Chaikin oscillation.

Third Angular Effect of Magnetoresistance in Quasi-One-Dimensional Conductors.

One-dimensional conductors

Angular dependent magnetoresistance oscillation (ADMRO) effect in α-(BEDT-TTF) 2 MHg(SCN) 4 [M: K, NH 4 ] has been studied as a function of the polar and azimuthal angles of applied magnetic field with respect to the most conducting a c -plane. The ADMRO effects in these two structurally similar compounds are drastically different in their azimuthal angle dependence and oscillation waveform. While the ADMRO in NH 4 Hg-salt is of the standard type arising from a warped cylindrical Fermi surface, that in KHg-salt is a novel type to be attributed to an open Fermi sheet. Calculation based on a model recently proposed for a quasi one-dimensional system quantitatively reproduces the essential features of the anomalous ADMRO in KHg-salt.

S. Kagoshima

Papers

Resonance effect in magnetotransport anisotropy of quasi-one-dimensional conductors

One‐Dimensional Conductors

Third Angular Effect of Magnetoresistance in Quasi-One-Dimensional Conductors.

One-dimensional conductors

The Origin of Anomalous Angular Dependent Magnetoresistance Oscillation Effect in α-(BEDT-TTF)2KHg(SCN)4