  We investigate the dynamics of two coupled macrospins connected to thermal
baths at different temperatures. The system behaves like a diode which allows
the propagation of energy and mag- netization currents in one direction only.
This effect is described by a simple model of two coupled nonlinear oscillators
interacting with two independent reservoirs. It is shown that the rectification
phenomenon can be interpreted as a a stochastic phase synchronization of the
two spin-oscillators. A brief comparison with realistic micromagnetic
simulations is presented. This new effect yields promising opportunities in
spin-caloritronics devices.
