Spin-polarized current in a rod-to-film structure

Properties are discussed of a ferromagnetic junction in the form of a rod contacting with a film. Very high current density of the order of j ∼ 109 A/cm2 may be achieved in the contact region that can lead to inversion of population of the spin energy subbands. The inversion depends strongly on the direction of the current (forward or backward). We prepared experimentally a rod-to-film structure and investigated high density current flowing through it. Current dependent radiation has been observed by means of a THz receiver, the radiation intensity being different for forward and backward currents. It shows that the radiation includes not only thermal contribution but also non-thermal (spin-injection) one.