  Topological insulators with the time reversal symmetry broken exhibit strong
magnetoelectric and magneto-optic effects. While these effects are
well-understood in or near equilibrium, nonequilibrium physics is richer yet
less explored. We consider a topological insulator thin film, weakly coupled to
a ferromagnet, out of thermal equilibrium with a cold environment (quantum
electrodynamics vacuum). We show that the heat flow to the environment is
strongly circularly polarized, thus carrying away angular momentum and exerting
a purely fluctuation-driven torque on the topological insulator film. Utilizing
the Keldysh framework, we investigate the universal nonequilibrium response of
the TI to the temperature difference with the environment. Finally, we argue
that experimental observation of this effect is within reach.
