Minigap in a long disordered SNS junction: analytical results

We review and refine analytical results on the density of states in a long disordered superconductor - normal-metal - superconductor junction with transparent interfaces. Our analysis includes the behavior of the minigap near phase differences zero and PI across the junction, as well as the density of states at energies much larger than the minigap but much smaller than the superconducting gap.Comment: 4 page

Anomalous density of states in a metallic film in proximity with a superconductor

We investigated the local electronic density of states in superconductor-normal metal (Nb-Au) bilayers using a very low temperature (60 mK) STM. High resolution tunneling spectra measured on the normal metal (Au) surface show a clear proximity effect with an energy gap of reduced amplitude compared to the bulk superconductor (Nb) gap. Within this mini-gap, the density of states does not reach zero and shows clear sub-gap features. We show that the experimental spectra cannot be described with the well-established Usadel equations from the quasi-classical theory.Comment: 4 pages, 5 figure

Models of electron transport in single layer graphene

The main features of the conductivity of doped single layer graphene are analyzed, and models for different scattering mechanisms are presented.Comment: 15 pages. Submitted to the Proceedings of the ULTI symposium on Quantum Phenomena and Devices at Low Temperatures, Espoo, Finland, to be published in the Journ. of Low. Temp. Phy

Exact eigenstate analysis of finite-frequency conductivity in graphene

We employ the exact eigenstate basis formalism to study electrical conductivity in graphene, in the presence of short-range diagonal disorder and inter-valley scattering. We find that for disorder strength, $W \ge$ 5, the density of states is flat. We, then, make connection, using the MRG approach, with the work of Abrahams \textit{et al.} and find a very good agreement for disorder strength, $W$ = 5. For low disorder strength, $W$ = 2, we plot the energy-resolved current matrix elements squared for different locations of the Fermi energy from the band centre. We find that the states close to the band centre are more extended and falls of nearly as $1/E_l^{2}$ as we move away from the band centre. Further studies of current matrix elements versus disorder strength suggests a cross-over from weakly localized to a very weakly localized system. We calculate conductivity using Kubo Greenwood formula and show that, for low disorder strength, conductivity is in a good qualitative agreement with the experiments, even for the on-site disorder. The intensity plots of the eigenstates also reveal clear signatures of puddle formation for very small carrier concentration. We also make comparison with square lattice and find that graphene is more easily localized when subject to disorder.Comment: 11 pages,15 figure

Anomalous Hall Effect in a 2D Rashba Ferromagnet

Contains fulltext : 159894.pdf (preprint version ) (Open Access

Anisotropy of spin-transfer torques and Gilbert damping induced by Rashba coupling

Spin-transfer torques (STT), Gilbert damping (GD), and effective spin renormalization (ESR) are investigated microscopically in a 2D Rashba ferromagnet with spin-independent Gaussian white-noise disorder. Rashba spin-orbit coupling induced anisotropy of these phenomena is thoroughly analysed. For the case of two partly filled spin subbands, a remarkable relation between the anisotropic STT, GD, and ESR is established. In the absence of magnetic field and other torques on magnetization, this relation corresponds to a current-induced motion of a magnetic texture with the classical drift velocity of conduction electrons. Finally, we compute spin susceptibility of the system and generalize the notion of spin-polarized current.Comment: 20 pages, 4 figure

Giant Magnetodrag in Graphene at Charge Neutrality

Contains fulltext : 119820.pdf (preprint version ) (Open Access

Japanese quail (Coturnix japonica) as the model of human aging retinal processes. Report № 2. Comparative analysis of the composition of retinoids isolated from retinal pigment epithelium of human and Japanese quail eyes

ABSTRACT Purpose. To compare the composition of retinoids of lipofuscin granules (LG) isolated from retinal pigment epithelium (RPE) of human cadaver eyes and Japanese quail. Material and methods. The Japanese quail′s retina and retinal pigment epithelium were chosen as a model of laboratory aging simulation. The evaluation of the amount of quail′s RPE retinoids was done by measuring of the fluorescence spectra and HPLC-analysis of the chloroform- methanol extraction from PRE. Results and conclusions. It has been shown that the spectral characteristics and the relative content of retinoids in lipofuscin granules (LG) isolated from retinal pigment epithelium (RPE) of human cadaver eyes and Japanese quail was very resemblance. These results allowed to consider Japanese quail (Coturnix japonica) as a suitable and enough adequate model of rapid human aging retinal processe

Edge states and distributions of edge currents in semi-infinite graphene

The distributions of edge currents in semi-infinite graphene under a uniform perpendicular magnetic field are investigated. We show unambiguously that the edge current is finite at the armchair edge but vanishes at the zigzag edge. It is shown that the current density oscillates with the distance away from the boundary and tends to zero deep inside the graphene. The study shows that the total current is independent of edge configurations. The interplay of the bulk and edge contributions to the total current is presented. The quantized plateaus of Hall conductivity at (4e (2)/h)(n+1/2) provide a direct evidence of the connection between the edge states and topological properties of relativistic fermions in a magnetic field.Physics, Condensed MatterSCI(E)EI0ARTICLE4431-4398