  Electromagnetic radiation of 1 - 10 THz range has been found at room
temperature in a structure with a point contact between a ferromagnetic rod and
a thin ferromagnetic film under electric current of high enough density. The
radiation is due to nonequilibrium spin injection between the structure
components. By estimates, the injection can lead to inverted population of the
spin subbands. The radiation power exceeds by orders of magnitude the thermal
background (with the Joule heating taking into account) and follows the current
without inertia.
