TY - JOUR

T1 - Switching between dynamic states in intermediate-length Josephson junctions

AU - Pagano, S.

AU - Sørensen, Mads Peter

AU - Parmentier, R. D.

AU - Christiansen, Peter Leth

AU - Skovgaard, Ove

AU - Mygind, Jesper

AU - Pedersen, Niels Falsig

AU - Samuelsen, Mogens Rugholm

N1 - Copyright (1986) by the American Physical Society.

PY - 1986

Y1 - 1986

N2 - The appearance of zero-field steps (ZFS’s) in the current-voltage characteristics of intermediate-length overlap-geometry Josephson tunnel junctions described by a perturbed sine-Gordon equation (PSGE) is associated with the growth of parametrically excited instabilities of the McCumber background curve (MCB). A linear stability analysis of a McCumber solution of the PSGE in the asymptotic linear region of the MCB and in the absence of magnetic field yields a Hill’s equation which predicts how the number, locations, and widths of the instability regions depend on the junction parameters. A numerical integration of the PSGE in terms of truncated series of time-dependent Fourier spatial modes verifies that the parametrically excited instabilities of the MCB evolve into the fluxon oscillations characteristic of the ZFS’s. An approximate analysis of the Fourier mode equations in the presence of a small magnetic field yields a field-dependent Hill’s equation which predicts that the major effect of such a field is to reduce the widths of the instability regions. Experimental measurements on Nb-NbxOy-Pb junctions of intermediate length, performed at different operating temperatures in order to vary the junction parameters and for various magnetic field values, verify the physical existence of switching from the MCB to the ZFS’s. Good qualitative, and in many cases quantitative, agreement between analytic, numerical, and experimental results is obtained.

AB - The appearance of zero-field steps (ZFS’s) in the current-voltage characteristics of intermediate-length overlap-geometry Josephson tunnel junctions described by a perturbed sine-Gordon equation (PSGE) is associated with the growth of parametrically excited instabilities of the McCumber background curve (MCB). A linear stability analysis of a McCumber solution of the PSGE in the asymptotic linear region of the MCB and in the absence of magnetic field yields a Hill’s equation which predicts how the number, locations, and widths of the instability regions depend on the junction parameters. A numerical integration of the PSGE in terms of truncated series of time-dependent Fourier spatial modes verifies that the parametrically excited instabilities of the MCB evolve into the fluxon oscillations characteristic of the ZFS’s. An approximate analysis of the Fourier mode equations in the presence of a small magnetic field yields a field-dependent Hill’s equation which predicts that the major effect of such a field is to reduce the widths of the instability regions. Experimental measurements on Nb-NbxOy-Pb junctions of intermediate length, performed at different operating temperatures in order to vary the junction parameters and for various magnetic field values, verify the physical existence of switching from the MCB to the ZFS’s. Good qualitative, and in many cases quantitative, agreement between analytic, numerical, and experimental results is obtained.

U2 - 10.1103/PhysRevB.33.174

DO - 10.1103/PhysRevB.33.174

M3 - Journal article

VL - 33

SP - 174

EP - 182

JO - Physical Review B (Condensed Matter and Materials Physics)

JF - Physical Review B (Condensed Matter and Materials Physics)

SN - 1098-0121

IS - 1

ER -