On Mon 11 Dec 2017 at 09:16:35 (-0500), rhkra...@gmail.com wrote: > From the Wikipedia article on "Magnetic storage": > > https://en.wikipedia.org/wiki/Magnetic_storage#Design > > "For reliable storage of data, the recording material needs to resist self- > demagnetisation, which occurs when the magnetic domains repel each other. > Magnetic domains written too densely together to a weakly magnetisable > material will degrade over time due to rotation of the magnetic moment one or > more domains to cancel out these forces. The domains rotate sideways to a > halfway position that weakens the readability of the domain and relieves the > magnetic stresses. Older hard disk drives used iron(III) oxide as the > magnetic > material, but current disks use a cobalt-based alloy.[1]"
The last sentence belongs at the end of the previous paragraph, which explains two changes made in disk technology: i horizontal→vertical, ii iron→cobalt. > I have trouble understanding that 2nd sentence: Yes, it doesn't parse, and it also doesn't clearly express which domains (grains or regions) are meant at each mention of the term. But before changing it, I'd want to check out the physics. "Magnetic domains written too > densely together to a weakly magnetisable material will degrade over time due > to rotation of the magnetic moment one or more domains to cancel out these > forces." and would like to rewrite it to be more clear--I'll make an attempt > below--suggestions are welcome: > > "Magnetic domains written too densely together to a weakly magnetisable > material will degrade over time--the magnetic forces which impact the disk > during rotation will cause one or more of the tiny magnetic domains to rotate > to (partialy) cancel out the intended magnetization (which stores the data)." > > I'll probably also replace "too densely together" with either "too close > together" or "too densely". > > Maybe I've combined too much of the third sentence into the second sentence > and it might stand rewriting as well. Cheers, David.
