arXiv subjects

A. Bezryadin

Publications and source records attributed to A. Bezryadin.

22 records · Page 2Linked to original sources

arXiv2001

Quantum Phase Slips in Superconducting Nanowires

We have measured the resistance vs. temperature of more than 20 superconducting nanowires with nominal widths ranging from 10 to 22 nm and lengths from 100 nm to 1050 nm. With decreasing cross-sectional areas, the wires display increasingly broad resistive transitions. The data are in very good agreement with a model that includes both thermally activated phase slips close to Tc and quantum phase slips (QPS) at low temperatures, but disagree with an earlier model based on a critical value of R_n/Rq. Our measurements provide strong evidence for QPS in thin superconducting wires.

cond-mat.supr-con↗

arXiv2000

Quantum suppression of superconductivity in ultrathin nanowires

We report measurements on ultrathin (<10 nm) nanowires produced by coating carbon nanotubes with a superconducting amorphous MoGe alloy. We find that nanowires can be superconducting or insulating depending on their normal state resistance $R_{N}$ compared to $R_{q}=h/(2e)^{2}$ -- the quantum resistance for Cooper pairs. If $R_{N}< R_{q}$ the tunneling of quantum phase slips (QPS) is prohibited due to strong damping, and so the wires stay superconducting. The insulating state, observed if $R_{N}> R_{q}$, is explained in terms of proliferation of quantum phase slips and corresponding localization of Cooper pairs. The observed superconductor-insulator transition is analogous to the dissipative phase transition which takes place in Josephson Junctions at $R_{N}= R_{q}$ (Penttila et al., Phys. Rev. Lett. Vol.82, p.1004, 1999)

cond-mat.supr-con↗

arXiv1999

Self-assembled chains of graphitized carbon nanoparticles

We report a technique which allows self-assembly of conducting nanoparticles into long continuous chains. Transport properties of such chains have been studied at low temperatures. At low bias voltages, the charges are pinned and the chain resistance is exponentially high. Above a certain threshold ($V_{T}$), the system enters a conducting state. The threshold voltage is much bigger than the Coulomb gap voltage for a single particle and decreases linearly with increasing temperature. A sharp threshold was observed up to about 77 K. Such chains may be used as switchable links in Coulomb charge memories.

cond-mat.mes-hall↗

arXiv1999

Evolution of avalanche conducting states in electrorheological liquids

Charge transport in electrorheological fluids is studied experimentally under strongly nonequlibrium conditions. By injecting an electrical current into a suspension of conducting nanoparticles we are able to initiate a process of self-organization which leads, in certain cases, to formation of a stable pattern which consists of continuous conducting chains of particles. The evolution of the dissipative state in such system is a complex process. It starts as an avalanche process characterized by nucleation, growth, and thermal destruction of such dissipative elements as continuous conducting chains of particles as well as electroconvective vortices. A power-law distribution of avalanche sizes and durations, observed at this stage of the evolution, indicates that the system is in a self-organized critical state. A sharp transition into an avalanche-free state with a stable pattern of conducting chains is observed when the power dissipated in the fluid reaches its maximum. We propose a simple evolution model which obeys the maximum power condition and also shows a power-law distribution of the avalanche sizes.

cond-mat.soft↗