It's magnetic. It's electric. It's photonic. No, this isn't going to be about a new superhero trio in the Marvel universe. This is all about our precious digital data. So let's prep for theatre, scrub our hands clean, and dig into the anatomy of what we use today to hold onto our trillions of digital bits.
There's certain an overall industry move towards the wholesale use of glass, but aluminium is still cheaper (albeit not by much), so for the small and ultra cheap markets, metal platters are still used.
The clue is in the fact that the read/write heads in a hard drive have to be within a handful of nanometres above the platter surface to affect the direction of the magnetic domains in the 'data' material. On that scale, the permanent magnets are effective on the other side of the galaxy, so despite their field strength, they're nowhere near close enough to affect the data. Also, the field between the magnets is very constrained - it's strong directly between them, but the field scales down rapidly outside of this region.
