  Topologically protected magnetic skyrmions in magnetic materials are
stabilized by interfacial or bulk Dzyaloshinskii-Moriya interaction (DMI).
Interfacial DMI decays with increase of the magnetic layer thickness in just a
few nanometers and bulk DMI only stabilizes magnetic skyrmions at low
temperatures. Consequently, more flexibility in manipulation of DMI is required
for utilizing nanoscale skyrmions in energy efficient memory and logic devices
at room temperature (RT). Here, we demonstrate the observation of RT skyrmions
stabilized by gradient DMI (g-DMI) in composition gradient engineered CoPt
single layer films by employing topological Hall effect, magnetic force
microscopy, and nitrogen vacancy scanning magnetometry. Skyrmions remain stable
at a wide range of applied magnetic fields and are confirmed to be Bloch-type
from micromagnetic simulation and analytical magnetization reconstruction.
Furthermore, we observe skyrmion pairs which may be explained by
skyrmion-antiskyrmion interactions. Our findings expand the family of magnetic
materials hosting RT magnetic skyrmions by tuning g-DMI via gradient polarity
and choice of magnetic elements.
