Magnetic hysteresis in thin film dc SQUID magnetometers

Measurements of the magnetic hysteresis of thin film dc SQUID magnetometers in applied magnetic fields up to 1 mT are reported herein. The hysteresis characteristic for the 77 K YBaCuO high Tc SQUIDS has a similar behavior to that of low Tc Nb thin film SQUIDs operating at 4.2 K. A quadratic dependence on the amplitude of the sweeping field was found in the high field limit.