Expert: Daniel Mazur - 2/17/2008

Question
QUESTION: I need to give a 10 minute oral presentation on an interesting topic in physics.

I've only begun my first year of physics, so the topics we've covered are projectile motion, kinematics, centripetal acceleration, gravitational fields, weightlessness. But, I'm sure anything interesting could apply; I'd just have to ask my teacher about it. So, I'm looking for a unique, interesting topic to look into!

Any ideas would be great!! :D

ANSWER: Hi,
I am not sure, how far I ought to go with my suggestions. In my field we have a lot of interesting topics: high-temperature superconductivity, carbon nanotubes, nanowires, quantum computing, spintronics... You need to send me a follow-up, if you want me to tell you anything more about any of them. I would spend too much time writing details about all of them. Please choose a couple of them first and I will gladly tell you more about your picks.
Good luck!
Daniel

---------- FOLLOW-UP ----------

QUESTION: Hi!

Spintronics sounds the most interesting. Could you elaborate a bit more on that? :]

Answer
Hello Shen-Shen,

spintronics (or spin-based electronics) is a concept which uses spin of atoms and electrons to transfer, store and process information. As you know, the electronics widespread today uses electron *charge* to transfer and process information. A device operating entirely on *spin* might have lower dissipation, be yet smaller than the limits on charge-based electronic devices and perhaps have other advantages too.

Spin, which is the magnetic property of elementary particles including electron, already plays role in storage devices - harddisks. In RAMs, I think, capacitor charges are still used, but huge effort has been put into making the storage on a magnetic basis and magnetic RAMs already exist, at least as prototypes.

The processing of spin information is also "in principle" solved, people are now working on a multitude of designs for practical realization of spin-diodes, spin-transistors etc. The most challenging part, at the moment, seems to be the transport of spin information. Although it is possible to separate spin flow from charge flow (it has been demonstrated, please use a follow-up again, if you want details), the spin information decays fast - say, on micrometer scale. It is unlikely that anytime soon we will have "spin wires" to facilitate the transport of spin information. So far it seems that we will be able to make devices (like integrated circuits) operating entirely on spins, but we will have to hook them up together with ordinary wires.

A good description of spintronics can be found at http://en.wikipedia.org/wiki/Spintronics and related links and in many of the links found when Googling "what is spintronics". I recommend that you look these resources up, some of them have illustrations that help very much - I gave up on explaining the details of devices here, I'd need a picture for that.

I hope I helped a bit, don't hesitate to ask some more.
Cheers,
Daniel