  Based on atomistic spin dynamics simulations, we report the ultrafast
generation of single antiferromagnetic (AFM) skyrmions in a confined geometry.
This process is achieved through an effective magnetic field induced by the
athermal inverse Faraday effect from a short laser pulse. The resulting field
can nucleate an isolated skyrmion as a topologically protected metastable state
in a collinear antiferromagnet with small Dzyaloshinskii-Moriya interaction.
The radius of a single skyrmion is shown to increase by applying a uniform dc
magnetic field and at increasing temperature. To investigate possible AFM
spin-caloritronics phenomena, we investigate the skyrmion dynamics under an
applied temperature gradient both analytically and numerically. The
antiferromagnetic skyrmions move longitudinally toward the hotter region, but
in contrast, small skyrmions in the very low damping regime move toward the
colder side, irrespective of the staggered topological charge number, with a
speed that is much faster than that of their ferromagnetic counterparts.
