Monday, March 19, 2012

Scientists Build Graphene From Scratch, Atom By Atom

The journalist is making it harder to understand what is going on.

IANAP but here's how I understand it thanks to google.

First, 85 tesla have been generated for very short instants in the lab so the article is wrong in saying 60 tesla is higher than ever achieved.

Graphene forms a two-dimensional lattice surface like a chicken wire fence.
For each molecule of graphene a single electron sticks out from the surface.
These electrons are free to hop around to other atoms.
In fact they act just like particles that have no mass and can travel at 1% of the speed of light. These quasiparticles are called massless dirac fermions. A fermion is a particle with certain properties, the nucles of a helium atom being one kind of fermion.
Electrons travelling at relativistic speeds is not earth shattering since that is what happens in gold atoms too. But the point is the electrons are free to sweep through the lattice without hindrance, and that if you can control the way the electrons move, you can control the apparent properties of the quasiparticles.

In 2010 Francisco Guinea in Madrid predicted that stretching graphene along all the axes of it crystal structure will make the electrons act as if subjected to a magnetic field.
http://www.gizmag.com/straining-graphene-creates-strong-pseudo-magnetic-fields/15891/ [gizmag.com]
http://physics.berkeley.edu/research/zettl/pdf/386.Science.329-Levy.pdf [berkeley.edu]

In July 2010 Michael Crommie proved the prediction, by growing bubbles of stretched graphene that stick up like pyramids from the platinum surface they were grown on. The electrons acted as if they were subjected to 300 tesla fields.
This technique works at room temperature.

The paper mentioned by the OP talks about designer Dirac fermions which means that you can create quasiparticles possessing the characteristics you desire by simply moving atoms around so they make electrons move in the way necessary to make the quasiparticles appear to exist. You can thereby freely mess with simulated mass, electrical and magnetic fields, etc. which might be very useful.
http://www.nature.com/nature/journal/v483/n7389/full/nature10941.html [nature.com]

The technique used in the OP experiment is low temperature and nanoscale. But based on Crommie's work it should not be hard to imagine processes in the future that could allow similar structures to be built quickly on a larger scale.

This is an exciting a relatively new field of research apparently but breathless reports using terms like designer babies or designer electrons when it is really designer quasiparticles, and saying that the fabric of reality is being messed with, is just distracting and does not help people who are not prepared to dive into the actual research paper to find out what is going on.

Source: http://rss.slashdot.org/~r/Slashdot/slashdotScience/~3/Cp18C7lD94c/scientists-build-graphene-from-scratch-atom-by-atom

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