  We have studied the effects of electrical current pulses on skyrmion
formation in a series of Co/Ni/Pt-based multilayers. Transmission X-ray
microscopy reveals that by applying electrical current pulses of duration and
current density on the order of $\tau$=50 $\mu$s and j=1.7x10$^1$$^0$ A/m$^2$,
respectively, in an applied magnetic field of $\mu$$_0$Hz=50 mT,
stripe-to-skyrmion transformations are attained. The skyrmions remain stable
across a wide range of magnetic fields, including zero field. The skyrmions
then remain stable across a wide range of magnetic fields, including zero
field. We primarily attribute the transformation to current-induced Joule
heating on the order of ~125 K. Reducing the magnetic moment and perpendicular
anisotropy using thin rare-earth spacers dramatically reduces the pulse
duration, current density, and magnetic field necessary to 25 $\mu$s,
2.4x10$^9$ A/m$^2$, and 27 mT, respectively. These findings show that energetic
inputs allow for the formation of skyrmion phases in a broad class of materials
and that material properties can be tuned to yield more energy-efficient access
to skyrmion phases.
