V. G. Cherkasova

Superconductivity in the novel semiconducting superlattices

Novel superconducting superlattices (SL) with transition temperature 4–6 K consisting only of semiconducting materials are discovered. Among them there are multilayers containing ferromagnetic chalcogenide EuS. Single films of the semiconducting materials constituting SL do not reveal superconductivity, and it appears only in multilayered systems. It is shown that superconductivity is confined to the interfaces between two semiconductors. The possible correlation between superconductivity and interfacial regualr grids of misfit dislocations is discussed.

Commensurate-incommensurate phase transition in the system of vortices and their images?

Abstract The authors attempt to explain their own experimental data on peculiar behaviour of critical currents of films placed in a parallel magnetic field in terms of commensurate-incommensurate phase transition in the system of vortices and their images.

“Quantum - size effect” in Mo/Si multilayers

Abstract The oscillating dependences of some kinetic and superconducting characteristics (ρn, ρ300/ρn, Tc,dHc⊥/dT|Tc) on the multilayer period D have been observed on superlattices Mo/Si. Extremum positions for all these dependences coincide, the period of oscillations being 35 A. These oscillating dependences resemble closely those observed on single films when the quantum size effect takes place. However the explanation of the results for multilayers in the same terms is rather doubtful due to a strong disorder in Mo layers. Different physical characteristics of the multilayers investigated reveal 2D and 3D behavior on the same samples.

Quasiperiodic superconducting V/Zr multilayers: critical magnetic fields and crossover

Critical magnetic fields parallel and perpendicular to the planes of quasiperiodic superconducting Fibonacci multilayers (ML) consisting of vanadium and zirconium are measured. The temperature dependence of the parallel critical field Hc∥ displays two crossovers. The Hc∥(T) dependence is of square-root type in the vicinity of the transition temperature Tc and linear at low temperatures. Between these temperature intervals, the dependence follows a power law: Hc∥∼(1−T/Tc)α, α=0,78±0,02. The complex nature of this dependence can be explained in the framework of the Ginzburg–Landau theory for a quasiperiodic ML, as well as by the scaling theory for fractal multilayers which takes into account the different structure length scales in the case of ML with a complex sequence of layers.

3D–2D crossover in melting transition on superconducting Mo/Si multilayers

Two-dimensional and three-dimensional vortex-lattice melting is observed on superconducting Mo/Si multilayers. Quasi-2D melting takes place in the range of high magnetic fields. The position of the melting transition on H-T phase diagram is in a reasonable quantitative accordance with the existing theories. Above melting line another phase transition is found connected with the decoupling in the liquid phase or with transition from hexatic to ordinary liquid. TAFF regime of the vortex motion is observed in the fluid phase governed by the plastic barrier charateristic for viscous liquid. TAFF regime with different activation energy takes place also in a vortex solid phase above the depinning line.

Two-, one- and zero-dimensional critical fluctuations observed on thin superconducting vanadium films

Abstract The authors experimentally demonstrate that critical fluctuations may be studied on transition metal superconducting thin films by monitoring the effective dimensionality of the fluctuations by means of an applied magnetic field.