Frequency and size dependence of ac Josephson effect in Nb/Au/YBCO heterojunctions

High frequency dynamics of Nb/Au/YBaCuO heterojunctions on tilted NdGaO3 substrates have been studied. The both integer and non-integer Shapiro steps have been observed at mm-wave frequencies. Unconventional dependence of the critical current and the amplitudes of Shapiro steps vs. applied microwave...

Full description

Saved in:
Bibliographic Details
Published in:Journal of physics. Conference series 2006-06, Vol.43 (1), p.1127-1130
Main Authors: Constantinian, K Y, Kislinski, Y V, Komissinski, P V, Borisenko, I V, Ovsyannikov, G A, Karminskaya, T Y, Soloviev, I I, Kornev, V K, Mygind, J
Format: Article
Language:English
Subjects:
Amplitudes
Critical current density
Heterojunctions
High frequencies
Integers
Josephson effect
Millimeter waves
Penetration depth
Physics
Substrates
Superconductivity
Superconductors
Vortices
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:High frequency dynamics of Nb/Au/YBaCuO heterojunctions on tilted NdGaO3 substrates have been studied. The both integer and non-integer Shapiro steps have been observed at mm-wave frequencies. Unconventional dependence of the critical current and the amplitudes of Shapiro steps vs. applied microwave power have been registered. Observed behavior deviates from existing theories of Josephson effect for junctions made from conventional or d-wave superconductors. Although the maximal size of the heterojunctions was smaller than the Josephson penetration depth, calculated from an averaged value of the critical current density, the experimental magnetic field dependences IC(H) deviate from the Fraunhofer pattern, pointing on non-uniform distribution of superconducting current density. Experimental results could be speculatively explained by origination of self-induced fractional magnetic vortices, which may take place in a junction where the amplitude and the phase of superconducting current alternate significantly over the junction area. Introducing a new lengthscale, which is much smaller than the Josephson penetration depth, the fractional vortices are considered, modifying the high frequency dynamics, namely the ac Josephson effect. Experimental results have been analyzed taking into account the second harmonic of superconducting current-phase relation and the influence of heterojunction capacitance.
ISSN:1742-6596
1742-6588
1742-6596
DOI:10.1088/1742-6596/43/1/274