  Thermal fluctuations can lift the degeneracy of a ground state manifold,
producing a free energy landscape without accidentally degenerate minima. In a
process known as order by disorder, a subset of states incorporating
symmetry-breaking may be selected. Here, we show that such a free energy
landscape can be controlled in a non-equilibrium setting as the slow motion
within the ground state manifold is governed by the fast modes out of it. For
the paradigmatic case of the classical pyrochlore XY antiferromagnet, we show
that a uniform magnetic field pulse can excite these fast modes to generate a
tunable effective free energy landscape with minima at thermodynamically
unstable portions of the ground state manifold.
