Superconductivity and localization of electrons in disordered two-dimensional metal systems

Effect of magnetic (phase) inhomogeneities on the conductivity of an antiferromagnetic La2CuO4 + δ single crystal at low temperatures

“…The suppression of local superconductivity by the magnetic field is also expected to break the pairs of charge carriers and reduce resistance [5]. We however observed positive magnetoresistance in the low temperature region at quite small currents, which is rather unexpected result.…”

“…The revealed changes in the behavior of hopping conductivity below 25 K correspond well to the known phenomena in inhomogeneous systems (mixtures of insulating and superconducting phases). Cooling of such a sys- tem below T c causes a transition from the variable-range hopping to the dependence R ∝ exp(∆/kT ), where ∆ is a superconducting gap, playing the same role as the band gap in insulators [5,6]. In our case, the formation of a superconducting phase can be related to the phase separation in lanthanum cuprates [4,7], which yields two phases with δ = 0 and δ > 0.…”

Mixed 1D-2D quantum electron transport in percolating gold film

“…Now consider more closely dependence L ϕ (T ) obtained from analysis of MR in 2D case using Eqs. (4) and (5). In the range 3-15 K, dependence L ϕ ∝ T −0.35 has been found ( Fig.…”

“…The first is associated with perturbations of the scattering potentials on the atomic scale: impurities, vacancies, and so on, and is often called microscopic. At the same time, MIT can also take place in inhomogeneous systems such as disordered mixtures of a metal and an insulator, granular metals, and the like [5,6], where the scale of disorder is well above interatomic distances, and where propagating electrons should overcome insulating regions (or boundaries) between the metallic clusters (grains). This second type of disorder is called macroscopic.…”

Simulation of a superconducting granular system on a honeycomb structure

“…, is the resistance for single electron tunnelling between neighboring grains [7]. In recent years a great experimental and theoretical interest has been manifested for two-dimensional periodic networks artificially fabricated by planar technology [8,9].…”