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The Josephson effect in ballistic point contacts between single-band and multi-band superconductors was investigated. It was found that in the case of Josephson junctions formed by a single-band and an s ±-wave two-band superconductor as well as by a single-band and a three-band superconductor the junctions become frustrated, showing the φ-contact properties. Depending on the ground state of a three-band superconductor with time-reversal symmetry breaking, the Josephson junction can have from one to three energy minima, some of which can be locally stable. We also study the behavior of a dc SQUID based on the Josephson junctions between single-band and multi-band superconductors. Some features on the dependences of the critical current and the total magnetic flux on the applied flux of a dc SQUID based on the Josephson point contacts between a singleband superconductor and an s ±-wave superconductor, three-band superconductor with broken timereversal symmetry and three-band superconductor without broken time-reversal symmetry as compared to the conventional dc SQUIDs based on single-band superconductors were found. The results can be used as an experimental tool to detect the existence of multi-band structure and timereversal symmetry breaking. [ABSTRACT FROM AUTHOR]

We have investigated Andreev reflection at interfaces between superconducting indium (Tc = 3.4 K) and several normal conducting nonmagnetic metals (palladium, platinum, and silver) down to T = 0.1 K as well as zinc (Tc = 0.87 K) in its normal state at T = 2.5 K. We analyzed the point-contact spectra with the modified one-dimensional BTK theory valid for ballistic transport. It includes Dynes' quasiparticle lifetime as fitting parameter Γ in addition to superconducting energy gap 2Δ and strength Z of the interface barrier. For contact areas from less than 1 nm2 to 10 000 nm2 the BTK Z-parameter was close to 0.5, corresponding to transmission coefficients of about 80%, independent of the normal metal. The very small variation of Z indicates that the interfaces have a negligible dielectric tunneling barrier. Also Fermi surface mismatch does not account for the observed Z. The extracted value Z ≈ 0.5 can be explained by assuming that practically all of our point contacts are in the diffusive regime. [ABSTRACT FROM AUTHOR]

Focuses on the dependence of the conductance of a one-dimensional ballistic ring on a potential barrier at one of the branches of the ring at nonzero temperature. Consideration of the case of a small potential barrier and a tunnel barrier; Possibility of direct measurement of the electron wave function phase variation upon tunneling.

Focuses on peculiarities of the electric conductivity of two-dimensional ballistic contacts that are sensitive to the nature of the confining potential as well as the existence of electrostatic potential inside the microconstriction. Information on the position of quantization levels from the position, amplitude and shape of the peculiarities.