Traces of superconducting correlations in nanographite films
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Traces of superconducting correlations in nanographite films S. G. Lebedev1,* 1
Department of Experimental Physics, Institute for Nuclear Research of Russian Academy of Sciences, 60th October Anniversary prospect, 7a, 117312 Moscow, Russia
Received: 18 June 2020
ABSTRACT
Accepted: 3 October 2020
The review of structural, electronic and magnetic properties of nanographite films is presented. The superconducting correlations such as AC-to-DC conversion associated with the reversed Josephson Effect, pinning of vortices on columnar topological structure of film surface observed in atomic force and magnetic force microscope, non-zero current at zero voltage in scanning tunneling microscope in local area of nanographite film surface have been found. These results are broadly in line with other our observations on abrupt resistivity jump accompanied by light emission having potential applications as switchers and compact light emitter. Further experiments on studies of local conductivity related to ion irradiation hoping to find a zero resistance state are proposed.
Springer Science+Business
Media, LLC, part of Springer Nature 2020
1
Introduction
The idea of high-temperature superconductivity (HTS) has appeared in pioneer works of W. A. Little [1] and V. L. Ginzburg [2], where the importance of organic macromolecules has been mentioned. Carbons as a material with small atomic mass have attracted the increasing attention in searches of HTS. Today there are several scientific teams’ explored different kinds of carbon structures such as graphite, graphene, diamond and their derivatives in trying to find HTS. Nanographite is a new class of mesoscopic systems which is situated between aromatic molecules and bulk graphite. In nanosized carbon systems, the topology of sp2 carbon networks crucially affects their p electronic states which govern the
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https://doi.org/10.1007/s10854-020-04603-0
electronic properties near the Fermi level. As can be seen below, nanographite (NG) is very promising material in this regard. The representation about structure and magnetic properties of variety carbon condensates has been collected in hand book of T. L. Makarova [3]. A. M. Ziatdinov [4] explored the nanographite crystallites and graphene edge states, which are responsible for magnetic properties and the value of density of states on Fermi level. Guomeng Zhao and Pieder Beeli for many years promote the idea of HTS in carbon nanotubes [5] and some of their arguments look very convincing. They proved the existence of granular HTS and a growing branch of the resistance at high temperatures in carbon nanotubes [6]. G. Baskaran with coauthors [7] have calculated HTS conditions by resonant valence bond
J Mater Sci: Mater Electron
method in doped graphene and diamond and promotes the study of Josephson signals in graphite [8]. A. M. Black-Schaffer and S. Doniach have demonstrated the possibility of d-wave HTS achieving in graphite layers at low but non-zero doping levels through an
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