Magnetic properties of square Josephson arrays with SIS and SNS junctions

The field dependence of the magnetic moment of 100x100 SIS and SNS Josephson arrays was investigated by SQUID-magnetometer. It was found, that the magnetic flux penetrated into SIS array by means of randomly distributed avalanches of tens and hundreds of flux quanta. The distribution of jumps by their size is a power function, which gives an evidence of self-organised criticality in regular Josephson structures. On SNS array the similar jumps were not observed, but dynamics of magnetic field in array was considerably asymmetric. The periodic peaks at external field, corresponding to integer and semi-integer of flux quanta per cell, were well observed only while absolute field was increased, and was imperceptible if the field is decreased