Magnetic media

A method of writing information to a magnetic medium, the magnetic medium comprising:

• a thin film magnet structure formed of a ferromagnetic alloy or compound;
• and
• one or more optical structures, each optical structure comprising a dielectric layer having an upper surface and a lower surface, the dielectric layer interposed between the thin film magnet structure and a substrate having a reflective portion with the lower surface facing the reflective portion;
• wherein the thin film magnet structure comprises one or more ferromagnetic domains and is coupled to the one or more optical structures, each of the one or more ferromagnetic domains having a magnetization that is switchable between two or more states,
• wherein each of the one or more optical structures is configured to increase absorbance of light at a target wavelength in the thin film magnet structure, configuration comprising that the corresponding dielectric layer is substantially transparent at a target wavelength, and has a thickness such that light at the target wavelength reflected from the lower surface interferes destructively with incident light at the target wavelength and light at the target wavelength reflected from the upper surface back towards the lower surface;
• the method comprising:
• illuminating a ferromagnetic domain with continuous-wave light including a target wavelength to cause that ferromagnetic domain to undergo all-optical magnetic switching.