  We use a 1.0-um-wide patterned Cu wire with an integrated nanomagnetic tip to
measure the statistical nuclear polarization of 19F in CaF2 by magnetic
resonance force microscopy (MRFM). With less than 350 uW of dissipated power,
we achieve rf magnetic fields over 4 mT at 115 MHz for a sample positioned
within 100 nm of the "microwire" rf source. A 200-nm diameter FeCo tip
integrated onto the wire produces field gradients greater than 10^5 T/m at the
same position. The large rf fields from the broadband microwire enable long
rotating-frame spin lifetimes of up to 15 s at 4 K.
