Non-linear hysteresis in thin film squid magnetometers

Measurements on both YBaCuO- and Nb-based thin film dc SQUID magnetometers reveal a non-linear hysteresis at fields above 0.1G. The nonlinear hysteresis is sensitive to sample temperature, but insensitive to the timescale of the field sweep in the millisecond region. Such hysteresis can be accounted for by the nucleation and subsequent displacement of vortices at the edges of the SQUID input washer. © 1993 IEEE