Abstract: An assembly for writing/reading high-density data on a recording media as a series of tags comprising a magnetic information bit pattern. The assembly includes an antenna positionable near the media; a source of electromagnetic radiation for producing an incident wave at least a portion of which can be coupled to the antenna; and, a means for coordinating a mutual positioning of the source of the electromagnetic radiation and the antenna, so that the antenna can generate a highly localized electromagnetic field in the vicinity of the media for inducing localized heating of the media. The assembly is capable of writing/erasing said high-density data by using an information signal for modulating the localized field generated in the vicinity of the media; the assembly is capable of reading by coordinating the mutual positioning of the antenna and the media.