N. A. Tulina

Simulating resistive switching in heterostructures based on oxide compounds

Simulations are used to study the influence of nonuniform electric field distribution at a heterojunction interface on the effect of bipolar resistive switching in oxide compounds. Computer models show that a conducting channel forms at the edge of a heterojunction area characterized by strong local increase in the electric field intensity. The computations are confirmed by the low temperature properties of metastable phases in heterojunctions based on high temperature superconductors.

Point-contact studies of superconducting properties degradation on the surface of HTSC single crystals

Abstract A sensitive method to investigate the superconducting properties of a HTSC single crystals surface at a depth of the order of 10 −6 –10 −5 cm is demonstrated. The method is based on the measurements of the temperature dependence of the point-contact resistance. The cleavage surface degradation of a Bi 2 Sr 2 CaCu 2 O 8 + δ single crystal at a depth of the order of 10 −5 cm is studied as a function of time from the change of the single crystal surface layer resistance. The characteristic times are of the order of several hours. The dependence of the critical temperature of the near-barrier layer of a Bi 2 Sr 2 CaCu 2 O 8 + δ single crystal on the resistance in this layer is obtained.

Nd2 − xCexCuO4 − y/Nd2 − xCexOy boundary and resistive switchings in mesoscopic structures on base of epitaxial Nd1.86Ce0.14CuO4 − у films

Reverse and stable bipolar resistive switching effect was observed in planar NdCeCuO - NdCeO - Ag heterostructures. It was shown that the current voltage charactereriscs of the BRSE observed has a diode character. Simulations were used to consider the influence of the nonuniform distribution of an electric field at the interface of a heterojunction on the effect of bipolar resistive switching in investigated structures. The inhomogeneous distribution of the electric field near the contact edge creates regions of higher electric field strength which, in turn, stimulates motion and redistribution of defects, changes of the resistive properties of the whole structure and formation of a percolation channel.

Resistive switching effect in thin-film heterojunctions based on electron-doped Nd2 − xCexCuO4 − y superconductor

Thin-film heterojunctions Nd2 − xCexCuO4 − y/Ag were obtained. The bipolar effect of resistive switching in these heterostructures was detected and investigated. X-ray diffraction data indicate the presence of a second phase in thin films; along with the basic phase Nd2 − xCexCuO4 − y, it affects the behavior of the interface of investigated heterojunctions and leads to an alteration of the type of conductivity. The threshold frequency of alternating voltage at which the resistive switching effect is observed in heterojunctions was detected.

NdCeCuO - NdCeO boundary and resistive switchings in mesoscopic structures on base of epitaxial NdCeCuO films

Reverse and stable bipolar resistive switching effect was observed in planar NdCeCuO - NdCeO - Ag heterostructures. It was shown that the current voltage charactereriscs of the BRSE observed has a diode character. Simulations were used to consider the influence of the nonuniform distribution of an electric field at the interface of a heterojunction on the effect of bipolar resistive switching in investigated structures. The inhomogeneous distribution of the electric field near the contact edge creates regions of higher electric field strength which, in turn, stimulates motion and redistribution of defects, changes of the resistive properties of the whole structure and formation of a percolation channel.

Resistive switching in mesoscopic heterostructures based on Nd 2– x Ce x CuO 4– y epitaxial films

Reversible and stable bistable resistive switching were observed in planar-type junctions Nd2–xCexCuO4–y/Nd2–xCexO1.75/Ag. It was shown that current transport in such junctions has a diode character with Schottky-like barriers in highly doped semiconductors. It was revealed that the key factor for switching is the presence of the second phase Nd2–xCexO1.75, deficient in oxygen, epitaxially germinated at the Nd2–xCexCuO4–y surface.

Resistive switchings and diode properties of heterostructures based on epitaxial superconducting Nd2–xCexCuO4–y films

Reversible and reliable bistable resistive switchings are observed in planar-type Nd2–xCexCuO4–y/Nd2–xCexO1.75/Ag junctions based on the Nd2–xCexCuO4–y superconducting films. Investigation of electronic structure of surface of the Nd0.5Ce0.5O1.75/Nd2–xCexCuO4–y via high-resolution X-ray photoelectron spectroscopy and atomic force microscopy (AFM) show that the key factor for the switchings is the presence of an oxygen-deficient Nd2-xCexO1.75 phase, epitaxially intergrown on surfaces of Nd2–xCexCuO4–y.

Frequency properties of heterostructures based on bismuth selenide upon bipolar resistive switching: Experiments and numerical simulation

The effect applied voltage frequency has on bipolar resistive switching in microcontact type heterostructures based on thin films and single crystals of bismuth selenide is studied both experimentally and via numerical simulation.

Numerical simulation of resistive switching in heterostructures based on anisotropic oxide compounds

Numerical simulation is used to study the effect anisotropic electrical conductivity and anisotropic oxygen diffusion have on the bipolar resistive switching effect in oxide compounds.

Resistive switching and diode properties of mesoscopic niobium oxide-based structures

The bipolar effects of resistive switching (BRS) in mesoscopic heterostrucures based on amorphous and crystalline niobium oxide films are considered. The BRS effect is more pronounced in the structures based on multiphase nanocrystalline niobium oxide films. It is shown that the threshold frequency for observing the BRS effect is of the order of 104 Hz. Switching is controlled via oxygen electrodiffusion to vacancies as the doping level of the contact area and the resistive properties of the heterocontact change.