  The absence of stray fields, their insensitivity to external magnetic fields,
and ultrafast dynamics make antiferromagnets promising candidates for active
elements in spintronic devices. Here, we demonstrate manipulation of the
N\'{e}el vector in the metallic collinear antiferromagnet Mn$_2$Au by combining
strain and femtosecond laser excitation. Applying tensile strain along either
of the two in-plane easy axes and locally exciting the sample by a train of
femtosecond pulses, we align the N\'{e}el vector along the direction controlled
by the applied strain. The dependence on the laser fluence and strain suggests
the alignment is a result of optically-triggered depinning of 90$^{\mathrm{o}}$
domain walls and their sliding in the direction of the free energy gradient,
governed by the magneto-elastic coupling. The resulting, switchable, state is
stable at room temperature and insensitive to magnetic fields. Such an approach
may provide ways to realize robust high-density memory device with switching
timescales in the picosecond range.
