Demagnetizing effects on the critical state in Josephson-junction arrays

It is known that in infinitely long Josephson-junction (JJ) arrays, a perfect critical state occurs at a sufficiently large maximum JJ current density i(max)* and the corresponding critical current density i(c)* is a step function of i(max)*. In this work, we demonstrate by numerical calculations that a critical state can also occur in striplike JJ arrays with strong demagnetizing effects if the maximum JJ current i(max) is sufficiently large. However, in the striplike arrays the critical state is never perfect, with field and current profiles always containing an oscillating component. The critical current i(c) tends asymptotically to a linear function of i(max).