Magnon excitation by spin injection in thin Fe/Cr/Fe films

The technique of Brillouin light scattering is used to observe strong excit ation of magnons in antiferromagnetically coupled trilayers of Fe/Cr/Fe at room temperature. The magnons are driven out of equilibrium by a microwave current applied in the trilayer through point contacts. The magnitude of th e scattering intensity is investigated as a function of the magnon wave num ber and applied magnetic field. Confirming recent theoretical predictions, the observations provide strong evidence of electronic spin injection in th e rf driving field.