Production of a thin x-ray amorphous aluminum nitride or aluminum silicon nitride film on a surface

A process for the production of a magneto-optical recording element, containing

• (A) an optically transparent dimensionally stable substrate,
• (B) a thermally alterable recording layer containing a lanthanide/transition metal alloy and
• (C) an aluminum nitride film on one or both sides of the said recording layer (B),
• the said process comprising the following steps in the stated order:
• (i) application of a lanthanide/transition metal alloy to the surface of the said substrate (A), resulting in the said recording layer (B),
• (ii) production of a sputter gas by vaporization of aluminum by reactive sputtering or reactive magnetron sputtering under reduced pressure in a process gas atmosphere consisting essentially of nitrogen and argon and one or more further noble gases selected from the group consisting of neon, krypton and xenon, the volume ratio of argon to the further noble gases being from 2:1 to 100:1 and the volume ratio of the further noble gases to nitrogen being from 2:1 to 10:1, so that the sputter gas results, and deposition of the aluminum nitride from the sputter gas onto the surface of the recording layer (B), resulting in the said film (C), and
• (iii) induction of a defined magnetization in the recording layer (B), oriented at right angles to the surface.