Directly coupled dc superconducting quantum interference device (SQUID) magnetometers onLaAlO3substrates were fabricated using ramp-edge superconductor/normal-metal/superconductor junctions, where Ag-dopedYBa2Cu3O7−xwas used for the electrode andPrBa2Cu3O7−xfor the normal-metal barrier. A flux noise of8×10−6 &Fgr;0 Hz−1/2at 10 kHz measured with a dc bias current was achieved at 75 K, which corresponded to a field sensitivity of400 fTHz−1/2for a magnetometer with a pick-up loop area of8.5 mm×7.5 mm.Most significantly, the noise floor increased at lower frequencies with a frequency dependence slightly less than1/f.The field noise of the SQUID magnetometers increased by only 25&percent; after cycling the devices from zero field to 500 mG. In a static earth’s magnetic field background, the field noise of the SQUID magnetometers increased by less than a factor of 2. ©1998 American Institute of Physics.