http://dspace.nbuv.gov.ua:80/handle/123456789/115158 2026-04-06T07:18:51Z http://dspace.nbuv.gov.ua:80/handle/123456789/117535 Macroscopic quantum phenomena in Josephson structures Barone, A.; Lombardi, F.; Rotoli, G.; Tafuri, F. The Josephson effect is a probe of unparalleled performances in the study of a variety of macroscopic quantum phenomena. In the present article an overview of important achievements and challenging trends is given referring, in particular, to macroscopic quantum tunneling and energy level quantization. The attention is mainly addressed to high-TC superconducting structures and recent investigations concerning nanostructures. 2010-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/117534 Coherent quantum phenomena in mesoscopicmetallic conductors (Review Article) Gogadze, G.A. The quantum coherent phenomena in mesoscopic cylindrical metallic conductors have been considered. Pure double-and single-connected normal samples were placed in a longitudinal magnetic field, which generated interference phenomena depending on the magnetic flux through the cross-section of the conductor. The period of the induced oscillations is equal to the flux quantum hc/e of the normal metal. The quantum states are formed in the structures by collisions of the electrons with the dielectric boundary of the sample. The magnetic flux is included in the expression for the spectrum of quasiparticles. The proximity effect and its influence on the modification of the spectrum of quantum coherent phenomena have been investigated. The behavior of cylindrical samples consisting of a superconducting (S) metal with a deposited thin pure normal (N) metal layer has been analyzed. In this structure the electrons are localized in a well bounded by a dielectric on one side and by a superconductor on the other. The specific feature of the generated quantized Andreev levels is that in the varying field H (or temperature T) each of the levels in the well can coincide periodically with the chemical potential of the metal. As a result, the state of the system experiences strong degeneracy and the density of states exhibits resonance spikes of the energy of the NS sample. This makes a significant contribution to the magnetic moment. A theory of the reentrant effect for NS structures has been developed, which interprets the anomalous behavior of the magnetic susceptibility of such structures as a function of the magnetic field and temperatures. 2010-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/117533 Theory of oscillations in the STM conductance resulting from subsurface defects (Review Article) Avotina, Ye.S.; Kolesnichenko, Yu.A.; van Ruitenbeek, J.M. In this review we present recent theoretical results concerning investigations of single subsurface defects by means of a scanning tunneling microscope (STM). These investigations are based on the effect of quantum interference between the electron partial waves that are directly transmitted through the contact and the partial waves scattered by the defect. In particular, we have shown the possibility imaging the defect position below a metal surface by means of STM. Different types of subsurface defects have been discussed: point-like magnetic and nonmagnetic defects, magnetic clusters in a nonmagnetic host metal, and nonmagnetic defects in a s-wave superconductor. The effect of Fermi surface anisotropy has been analyzed. Also, results of investigations of the effect of a strong magnetic field to the STM conductance of a tunnel point contact in the presence of a single defect has been presented. 2010-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/117532 Persistent currents, flux quantization and magnetomotive forces in normal metals and superconductors (Review Article) Kulik, I.O. The notion of persistent current comes back to orbital currents in normal metals, semiconductors and even insulators displaying diamagnetic behavior in weak magnetic fields, but came to focus at the discovery of current persistence and magnetic flux quantization at large fields in atomically big but macroscopically small (mesoscopic) objects. The phenomenon bears much similarity with supercurrents in superconductive metals. We will review progress in developing of our understanding of the physical and technological aspects of this phenomenon. The exact solution for currents, magnetic moments and magnetomotive forces (torques) in crossed magnetic fields are presented. Time-dependent phenomena in crossed magnetic and electric fields, and in possibility of spontaneous persistent currents and of work extraction from static and dynamic quantum states are discussed. 2010-01-01T00:00:00Z