Tag Archives: W. Patrick Cray

Happy 2009!

I just read ‘How spintronics went from the lab to the iPod’ by W. Patrick McCray in the online January 2009 issue of Nature Nanotechnology, it’s here. The author is in the history department of the University of California at Santa Barbara and he provides an intriguing view of how nanotechnology, electronics, academic, military, and business interests converged in various applications, the best known being the iPod. He also provides a brief history of how the discovery (giant magnetoresistance) was made by two teams independently of each other (but almost simultaneously) who agreed to share credit and ultimately a Nobel prize. (BTW, that last bit contrasts nicely with Crick and Watson with their double helix and the way they took full credit when at least some should have gone to Rosalind Franklin.)

For anyone who doesn’t know about giant magnetoresistance (GMR), we start with magnetoresistance (from the article),

Magnetoresistance, a change in the electrical resistance of a conductor caused by an applied magnetic field was first observed … in 1857 (p. 2)

The source was not discovered until quantum mechanics became an area of interest,

… the physics underlying electron spin — which is the ultimate source of magnetism in most materials — dates back to … the golden era of quantum mechanics. The effect was quite small … but that all changed … in 1988. [One team in Germany and another team in France sandwiched very thin layers {1 nm} of nonmagnetic materials with magnetic materials to observe a significant {10% for one team and 50% for the other team} change in electrical resistance in the presence of a magnetic field. Presumably lowering the resistance which {researchers at IBM realized} meant that disc drives could become smaller and hold more information {which is how we ultimately with an iPod}.

GMR also represented the first example of a new kind of technology called ‘spintronics’, so-called because it exploits the spin of the electron, as well as its electric charge, store and process information. p. 2 (the stuff in square brackets is my attempt to massage the information so I don’t quote the entire article]

Do read the story.