  Spintronic devices based on magnetic skyrmions are a promising candidate for
next-generation memory applications due to their nanometre-size,
topologically-protected stability and efficient current-driven dynamics. Since
the recent discovery of room-temperature magnetic skyrmions, there have been
reports of current-driven skyrmion displacement on magnetic tracks and
demonstrations of current pulse-driven skyrmion generation. However, the
controlled annihilation of a single skyrmion at room temperature has remained
elusive. Here we demonstrate the deterministic writing and deleting of single
isolated skyrmions at room temperature in ferrimagnetic GdFeCo films with a
device-compatible stripline geometry. The process is driven by the application
of current pulses, which induce spin-orbit torques, and is directly observed
using a time resolved nanoscale X-ray imaging technique. We provide a
current-pulse profile for the efficient and deterministic writing and deleting
process. Using micromagnetic simulations, we also reveal the microscopic
mechanism of the topological fluctuations that occur during this process.
