Magnetism and magnetization dynamics in thin film ferromagnets

In this PhD thesis we investigated the feasibility to build a spin-flip laser, a spintronic device recently proposed by Kadigrobov that can emit radiation within the so-called terahertz gap. In the first part of this thesis, we describe point contact spectroscopy experiments which were meant as a first step to the final observation of radiation coming from the spin-flip laser. The ferromagnet used in our spin-flip laser is SmCo5, a hard ferromagnet with a very large coercive field. The next chapter of the thesis describes the sputter growth of thin films of Sm-Co. We found that one of the main problems of building a spin-flip laser is the issue of spin current injection and the relaxation of the spin current in an adjacent layer. In the last chapters of the thesis, we use the ferromagnetic resonance technique to study how the spin currents behave at the interface of a ferromagnet and a normal metal with large spin-orbit coupling, such as Pt or Pd or a normal metal with weak spin-orbit coupling, such as Cu.Quantum Matter and Optic