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Comment by Neywiny | Hacker News Reader

> Seagate is leveraging its heat-assisted magnetic recording (HAMR) technology to deliver its 6.9TB platter. If you want to check out how Seagate's HAMR technology works, check out our previous coverage. In a nutshell, HAMR uses heat-induced magnetic coercivity to write to a hard drive platter.

Wow so heat assisted magnetic recording is using heat to magnetically record data. Incredible explanation.

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Heating a ferromagnetic material lowers it coercivity -- the heat softens it and makes it less magnetically "springy". And if heated enough it fully loses its magnetization.

So, to write, zap the area with a laser to heat it up. The coercivity is lowered. This lets a weaker magnetic field work to magnetize the area. This allows packing more densely, as the weak field will not affect the neighbouring cooler and higher coercivity regions.

(I think.)

This is not the first time lasers have been used to write to magnetic media. Magneto-optical discs (e.g. Sony's MiniDisc) were erased using laser heat. (MO discs also were read with laser, the ferromagnetic material used had different optical properties depending on magnetization.)

I guess you could say that MiniDisc was the original HAMR format.

Yeah, don't try to learn science from Tom's Hardware.

Mofo magnets! How do they work? With heat?!

We prefer steam over magnets especially since nobody knows how they work, but whatever you do, don't get the magnets wet!

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