  We report the observation of room-temperature magnetic skyrmions in
Pt/Co/Os/Pt thin-film heterostructures and their response to electric currents.
The magnetic properties are extremely sensitive to inserting thin Os layers
between the Co-Pt interface resulting in reduced saturation magnetization,
magnetic anisotropy and Curie temperature. The observed skyrmions exist in a
narrow temperature, applied-field and layer-thickness range near the
spin-reorientation transition from perpendicular to in-plane magnetic
anisotropy. The skyrmions have an average diameter of 2.3{\mu}m and transport
measurements demonstrate these features can be displaced with current densities
as low as J = 2x10^4 A/cm^2 and display a skyrmion Hall effect.
