Archive for July, 2007

Anderson and the theory for high-tempearture superconductor, again?

Wednesday, July 25th, 2007

Well, that is right. The Nobel Prizer Philip Anderson is making the headlight on Science again. And, once more, the theory for high-Tc superconductor. I have to say that the mechanism of high-Tc superconductor is really his field, or rather his problem per se. The paper is well-written and in a typical Anderson style. For example, there is one sentence referring the literature of pairing mechanism that I’d like to cite.

This mythology is popular among science journalists, who dramatize both the element of competition and the search for The Secret.

So, you won’t be surprised to hear what he is saying next:

I argue here that this need for a bosonic glue is folklore rather than the result of scientific logic.

Yummy…! Actually, he shows(proves) that he is right. Many researchers take pairing granted when they build their models to explain the phenomena using a Eliashberg picture. The pairing of two repulsive electrons, which is one of the key points in BCS superconductivity theory, is resulted from either a “dynamic screening” or pairing in anisotropic wave context.

I just think it is better quote his entire last paragraph here as a ending point.

The crucial point is that there are two very strong interactions, U (>2 eV) and J (~0.12 eV), that we know are present in the cuprates, both a priori and because of incontrovertible experimental evidence. Neither is properly described by a bosonic glue, and between the two it is easy to account for the existence of antiferromagnetism, d-wave superconductivity, and many other phenomena of high-Tc superconductivity. Whether any additional “glue” exists is of lesser interest. We have a mammoth and an elephant in our refrigerator—do we care much if there is also a mouse?

It once again proves that,

“Making the simple complicated is commonplace; making the complicated simple, awesomely simple, that’s creativity.” -Charles Mingus.

What is the point here?

Back on track

Tuesday, July 24th, 2007

Finally I came back to Lincoln. Everything is great except one thing, I’ve been suffering the jet lag ever since back. A consequence of that is that this blog updating is very infrequent if not at all. As time goes on, I’m feeling better on daily base, then, I’m planning to restore the order and keep me breathing and this blog alive. :-(

One thing I want to say about this trip is that it is just very wonderful, especially for my families.