  Magnetic skyrmions hold promise for spintronic devices. To explore the
dynamical properties of skyrmions in devices, a nanoscale method to image spin
textures in response to a stimulus is essential. Here, we apply a technique for
operando electrical current pulsing of chiral magnetic devices in a Lorentz
transmission electron microscope. In ferromagnetic multilayers with interfacial
Dzyaloshinskii-Moriya interaction (DMI), we study the creation and annihilation
of skyrmions localized by point-like pinning sites due to defects. Using a
combination of experimental and micromagnetic techniques, we establish a
thermal contribution for the creation and annihilation of skyrmions in our
study. Our work reveals a mechanism for controlling skyrmion density, which
enables an examination of skyrmion magnetic field stability as a function of
density. We find that high-density skyrmion states are more stable than
low-density states or isolated skyrmions resisting annihilation over a magnetic
field range that increases monotonically with density.
