Wednesday, August 05, 2009

Phonon Signatures Found for "Kink" in High-Tc Superconductors?

Anyone following this blog would have seen my catalog of publications on the renormalization effect of the high-Tc cuprate band structure, resulting in the so-called "kink". We have something new to add here.

A new publication in PRL from the Stanford group[1] has reported on ARPES measurement on single and multilayer Tl cuprate family. They look at the kink for single, bilayer, and trilayer compounds and found that the kink has a momentum dependence.

Now this is significant because of two things:

1. If the coupling is electron-magnetic mode, then they argue that one should not expect any significant changes between these set of compounds.

2. But if it is electron-phonon (buckling phonon) coupling, then such changes is expected.

So the major conclusion here is that the latest ARPES data is not consistent with the magnetic spin coupling as the cause of the kink in the band dispersion. Whether this rules out such coupling as the "glue" that causes superconductivity, that remains to be seen.


[1] W.S. Lee, Phys. Rev. Lett. v.103, p.067003 (2009).

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