Anatoly S. Sidorenko

Superconducting and normal properties of the set of Mo/Si superlattices with variable Si layer thickness

We report the results of the superconducting and kinetic parameter measurements (transition temperature Tc, parallel and perpendicular critical fields Hc2, resistivity in the normal state) on a set of Mo/Si superconducting superlattices with a constant metal layer thickness dMo=22 A and variable semiconducting one dSi(14–44 A). Our data show a monotonic dependence of all measured parameters on dSi. It is found that the Josephson interlayer coupling energy depends exponentially on the spacer thickness. The data obtained allowed us to determine the characteristic electron tunneling length for amorphous silicon with high precision. It is equal to 3.9 A. Enhancement of interlayer coupling leads to the Mo. Si multilayer transition temperature increasing, in agreement with Horovitz theory and with the experimental data on high-Tc materials.

Giant oscillations of coupling strength on Mo/Si multilayers with the constant thickness of semiconductor layers

We report the observation of anisotropy ratio γ and interlayer coupling strength oscillations with variation of metal layer thickness on Mo/Si multilayer series with constant Si layer thickness. These oscillations correlate with previously found oscillations of TC, R300/Rn and dHc⊥/dT. The giant amplitude of γ oscillations makes one to believe that all oscillation effects are due to the variation of the Josephson coupling strength. Possible origin of these unusual effects is discussed.

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.

Change of the effective fluctuation dimensionality in vanadium thin films in a magnetic field

Abstract Lowering of the effective fluctuation dimensionality in the critical region has been found for thin superconducting vanadium films placed in strong perpensicular magnetic fields. The effect shows itself as a change of the critical index characterizing the temperature dependence of the excess film conductivity. By varying the magnetic field, one can observe both two-dimensional and zero-dimensional critical fluctuations on the same specimens.

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.