The practical approach is to integrate a laser and optical system (waveguide and aperture) into the magnetic recording head and engineer an efficient coupling of the laser energy into the media.
Additionally, a whole new class of magnetic materials must be created or adjusted, and the media overcoat and lubrication materials must be engineered to withstand the heating and allow for effective coupling of the heat energy into the recording layer.
During this recording process, thermal conduction must be controlled very precisely to balance heating and cooling the media.
The HAMR procedure is amenable to sputter deposition using existing media manufacturing tools, although some cathode modification and in-situ thermal annealing may be required; if thermal annealing is necessary then choice of media substrate may be limited to higher temperature materials such as glass and/or ceramic oxide materials. Neither of these would be major obstacles to manufacturing.