Arrays of "Topological Insulators": a Step Towards Exotic Electronics

LilaG writes with a paragraph from Chemical & Engineering news: "Chemists in China have precisely grown arrays of ultrathin flakes of bismuth selenide and bismuth telluride on a surface. The bismuth compounds belong to a recently discovered – and weird — class of materials called topological insulators, which conduct electrons only along their surfaces, not through their insides. Researchers think topological insulators promise a new realm of fast, energy-efficient electronic and spintronic devices. Making well-defined nanoparticle arrays such as the new study's flakes is a key step towards such devices."

Well, now

[Khyber]

Modifiable bandgaps for multi-wavelength LEDs, anyone? Multi-spectrum lasers?

Exotic Electronics

[Anomalyst]

Oboy, body contour hugging catsuits and padded manacles made of bismuth.
Count me in!

Good paper, but not a major breakthrough

[gotfork]

Being able to grow well-ordered arrays of bismuth selenide and bismuth telluride nanoplates is a great improvement over the original VLS/Van der Waals growth method developed by Cui's group, in which you could grow similar nanoplates but they were randomly distributed across the surface (it's a pain to work with them since you have to track whichever one you want to use down by hand). However, it's not a huge breakthrough in the field and doesn't put us much closer to any of the proposed devices which would actually use topological insulators. Although they don't show any transport data in the paper the quality of the nanoplates may not be that good based on the ARPES data shown -- the fermi level falls well into the conduction band, and not in the gap as would be required by most interesting applications. Also, a more commonly used technique called molecular beam epitaxy (MBE) can also be used to grow continuous films of these materials across whole wafers, and several groups have demonstrated very high quality films this way.
TL;DR: A nice scientific paper, on an exciting topic, but no major breakthrough. Several interesting uses for TIs have been proposed but they are all very far out, everything going on right now is still basic research. (Full disclosure: I'm not affiliated with either group, but I am sitting in the lab measuring some TI-based devices right now).

A rather mysterious subject, though:

[Hartree]

I've been to a couple of talks on TIs and read very briefly on them. It's at the bare edge of my admittedly atrophied knowledge (20 years of doing things other than physics makes for a lot of forgetting).

Whenever an article on TIs comes up on slashdot, it gets few replies. I suspect that even those with some idea of what all the excitement is about find it hard to explain on a level that even some fairly cluefull slashdotters can understand. I've got some ideas of what it's about, (New electronic states to

insulates .. until it cracks

[citizenr]

insulates .. until it cracks and all of a sudden there IS a surface between 2 previously insulated wires.

Re:

[nedlohs]

Lots of current circuit boards won't work when snapped in half either.

Cracking one can touch two wires/tracks/pins that weren't touching before too.

another bismuth compound

[treeves]

coats and soothes. I do not like the taste of Pepto-Bismol though.

Re:

[MiG82au]

No. Only high frequency currents concentrate towards the surface. And I believe this has nothing to do with cars and lightning; that's just a matter of being enclosed in a conductive cage.