In accordance with the present invention, there is provided a composition of matter comprised of about 90% by weight of particles smaller than about 100 nanometers comprised of magnetic atoms. These nanomagnetic particles have a first magnetic moment between about 2 to about 3,000 emu per cubic centimeter, and a magnetic durability such that after about 6 months the magnetic moment does not vary by more than 5%. The nanomagnetic material, when used with implantable medical devices, upon exposure to magnetic resonance imaging (MRI) radiation, reduces the eddy currents, improves the imageability, cancels the positive susceptibility, improves the magnetic field about such devices, and may be used to modify the magnetic susceptibility of such devices. Also provided in accordance with the present invention is a preferred process for preparing such nanomagnetic material, certain preferred devices that comprise the nanomagnetic material, and a process for preparing certain flexible implantable medical devices that comprise the nanomagnetic material.