Eur. Phys. J. B 61, 59-66 (2008)
https://doi.org/10.1140/epjb/e2008-00040-2

Low-field magnetic response of multi-junction superconducting quantum interference devices

DMI, Università degli Studi di Salerno, Via Ponte Don Melillo, 84084 Fisciano (SA), Italy

Corresponding author: ^a rdeluca@unisa.it

Received: 15 November 2007
Published online: 31 January 2008

Abstract

The magnetic states of multi-junction superconducting quantum interference device containing 2N identical conventional Josephson junctions are studied by means of a perturbation analysis of the non-linear first-order ordinary differential equations governing the dynamics of the Josephson junctions in these devices. In the zero-voltage state, persistent currents are calculated in terms of the externally applied magnetic flux Φ_ex . The resulting d.c. susceptibility curves show that paramagnetic and diamagnetic states are present, depending on the value of Φ_ex . The stability of these states is qualitatively studied by means of the effective potential notion for the system.