
Heat-assisted magnetic recording - luu
https://en.wikipedia.org/wiki/Heat-assisted_magnetic_recording
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tedsanders
Various thoughts on this technology:

+Hard drive progress has been slowing since the last major advance in the
2000s (tunnel magnetoresistance read heads, which are now maturing). Heat-
assisted magnetic recording (HAMR) is the most likely next evolution of hard
drives.

+The main problem with increasing bit density on hard drives is as you make
the bits smaller, they become less stable. You can increase their stability by
increasing their magnetic coercivity, but then the tradeoff is that the bits
become harder to write. Heat-assisted magnetic recording is a technology that
makes bits easier to write, which will make it possible to use smaller (higher
coercivity) bits.

+The idea is not new, and it even enjoyed commercial realization in the 1980s
in magneto-optic discs.

+Seagate is one of the leaders in HAMR technology, but their release dates
keep getting pushed back. Right now the latest word is that they'll be
commercially available in 2017.

+I've heard the main problem with HAMR now is the thermal stability of the
plasmonic antenna. Because the magnetic bits are much smaller than the
wavelength of laser light, conventional optics cannot be used. Instead, the
head has a vertical waveguide with a plasmonic antenna at the end, which
concentrates the light at the bit being written. Unfortunately, a side-effect
of heating the magnetic bits is that the antenna also gets hot, and they can
fail after just ~100 writes. Engineers are working to solve this and I'm
confident they will, but right now this is the main problem with HAMR and why
it's taken so long to get to market, at least from what I've heard.

Source: I am a magnet scientist

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castratikron
I did my thesis on computer simulations of heated magnetic grains for HAMR
research. They say that this tech could provide densities up to 1TBit/in^2.

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SMR1
You can buy regular (not HAMR) HDDs with the same areal density of 1TBit/in^2
today: Seagate 8TB Archive HDD, Toshiba 2.5" HDD.

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castratikron
Can I guess by your username that they use shingled magnetic recording? I did
that thesis a few years ago and I never went into the field. I remember SMR
and HAMR being the two big ideas at the time.

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cnvogel
The submitter might have been triggered to look the topic up on Wikipedia by
the most recent (Aug 10, 2015) installment on Ben Krasnow's Applied Science
videos:

Learn how magneto-optical storage discs work, and see how a focused laser can
directly alter a material's optical characteristics.

[https://www.youtube.com/watch?v=UTquUbvzJII](https://www.youtube.com/watch?v=UTquUbvzJII)

This video uses a magneto-optical disk as an example material, but there also
the material is heated up above the curie point to allow the bit-domains to
swap orientation. Readout is optical, though. (hence the name)

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scottlocklin
People forget the NeXT Cube originally came with a version of one these
(magneto optic read outs based on Kerr Rotation); Jobs was a visionary for
certain.

I actually worked on a version of this (Cobalt-Platinum multilayers) for a
summer internship with Mark Kryder at the Data Storage Systems Center; a
formative experience for me. The Seagate technology described here is probably
largely based on his work.

