Kristin: Searching for the term ‘nano’ on Google returns 109 million entries. But if you take out ‘ipod’ from that search, you lose 49 million of these entries. This time last year, Peter Binks reported on an article in nature which showed that there is some nano in the iPod after all.
Peter: I’m often asked: “Is there nano in the iPod nano, or is it just a marketing ploy?”. I’ve been confident in myself that the circuitry, the memory, and the screen all contained nanostructured materials, but I’d privately wondered if these were important – did they make the device as distinctive and powerful as it is?
The latest issue of Nature has provided the answer. In an article about “The physics prize inside the iPod”, Geoff Brumfiel explains that the key effect is giant magnetoresistance (GMR). The effect has been heralded as one of the first major applications of the fields of nanotechnology and ’spintronics’, opening up a way to build much smaller magnetic heads. Basically the heads consist of multiple layers of magnetic and non-magnetic materials only tens of nanometres thick. When all the layers were aligned in the same direction, electrons with the same alignment passed through the material easily, whereas those with the opposite alignment struggled. But when the layers were organized in an alternating ‘up-down’ alignment, all electrons encountered resistance. The net effect was a rise in resistance that was much bigger than any seen before. This led to devices that are very sensitive to tiny magnetic fields.
I’m delighted. The iPod is one of the most exciting developments of the last decade, and we can now confidently claim it in the nano family!
Originally published on Blog@NanoVic for Nanotechnology Victoria.