Vladimir M. Svistunov

Inelastic electron tunneling across magnetically active interfaces in cuprate and manganite heterostructures modified by electromigration processes

We report a study of the electron tunneling transport in point-contact junctions formed by a sharp Ag tip and two different highly correlated oxides, namely, a magnetoresistive manganite La0.66Ca0.34MnO3 and a superconducting cuprate LaBa2Cu3O7−x. Strong chemical modifications of the oxide surface (supposedly, oxygen ion displacements) caused by applying high voltages to the junctions have been observed. This effect is believed to be responsible for an enormous growth of inelastic tunneling processes across a transition region that reveals itself in an overall V-shaped conductance background, with a strong temperature impact. The mechanism of the inelastic scattering is ascribed to charge transmission across magnetically active interfaces between two electrodes forming the junction. To support the latter statement, we have fabricated planar junctions between Cr and Ag films with an antiferromagnetic chromium oxide Cr2O3 as a potential barrier and at high-bias voltages have found an identical conductance t...

Background conductance of HTSC tunneling junctions

It is shown that some principles of the tunneling spectroscopy of conventional metals cease to be true in the case of the tunneling spectroscopy of metal oxides.

Evidence for Strong Electron-Magnon Coupling in Gadolinium

Tunneling spectroscopy measurements on normal state Gd–Gd oxide–Al junctions have been performed. Small deviations from the overall parabolic dependence of conductance on voltage were revealed and analyzed using a theoretical approach, taking into account interactions of tunneling electrons with elementary excitations in the oxide layer and metal electrodes. These processes have been studied by calculating the even and odd conductances that characterize the symmetrical (emission of oxide phonons) and asymmetrical (self-energy effects in electrodes) processes, respectively. It has been found that in gadolinium, one of the simplest magnetic metals known, an interaction of electrons with magnetic excitations is as important as the electron-phonon contribution. This result explains the difference between the calculated electron-phonon coupling parameters and the experimentally derived electron mass enhancement factors in magnetic rare-earth metals.

Electron Tunneling into a Narrow Band Conductor.

Electron tunneling between a Fermi metal and a narrow band conductor with non-quadratic E – k relationship is treated. It is shown that the tunneling characteristics of such junctions are very sens...

Electron-boson interaction in nonsuperconducting magnetic metals

Gadolinium-and chromium-based normal metal-insulator-metal tunnel junctions were studied. Spectral functions of the Gd and Cr electron-boson interaction were reconstructed, from which it follows that the magnetic subsystem plays a noticeable role in the electron transport in magnetic metals.