Hot electrons in magnetic point contacts as a photon source

Abstract

We propose to use a point contact between a ferromagnetic and a normal metal\nin the presence of a magnetic field for creating a large inverted\nspin-population of hot electrons in the contact core. The key point of the\nproposal is that when these hot electrons relax by flipping their spin,\nmicrowave photons are emitted, with a frequency tunable by the applied magnetic\nfield. While point contacts is an established technology their use as a photon\nsource is a new and potentially very useful application. We show that this\nphoton emission process can be detected by means of transport spectroscopy and\ndemonstrate stimulated emission of radiation in the 10-100 GHz range for a\nmodel point contact system using a minority-spin ferromagnetic injector. These\nresults can potentially lead to new types of lasers based on spin injection in\nmetals.\n