Various apparatuses, systems, methods, and media are disclosed to provide a magnetic recording medium that capping layer doped with an effective amount of metal to control grain-to-grain exchange coupling in a capping layer. A magnetic recording medium includes a substrate, a magnetic recording layer (MRL) on the substrate, and a capping layer on the MRL. The capping layer include Co and is doped with a metal (e.g., Ru or Ta) in a range from 1 atomic percent to 5 atomic percent, inclusive.