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【求助】关于pseudogap的问题
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我是化学出身的,想请教物理方面的高手,pseudogap是什么意思哦?最好能用比较通俗的语言解释一下,我更容易理解,呵呵 [ Last edited by ddx-k on 2008-12-14 at 20:00 ] |
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楼上说的很好，不过关于赝能隙的机理目前还没有一个统一的认识，预配对只是大家普遍接受的一个主流观点，这个还有争议，可以看一下这篇综述文章 Physics Reports 431 (2006) 231 – 259 至于electronic stripes的问题，其实在很多强关联体系里面都发现了类似的electronic phase separation问题，这个是电荷（自旋）在实空间的周期性排列，公度调制的情况下，结构比较稳定。这个可以用衍射技术测量到的，有人认为条纹相结构是高温超导的基态之一，另一个比较稳定的相是最佳掺杂的超导组分。但是对于动态的条纹相目前认识的还不够清楚，如果感兴趣的话可以参考这篇文献 REVIEWS OF MODERN PHYSICS, VOLUME 75 （2003） 1201 |
6楼2008-03-29 11:41:04
gaoky2008
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Pseudogap From Wikipedia, the free encyclopedia A pseudogap is a term from the field of high-temperature superconductivity which describes an energy (normally near the Fermi energy) which has very few states associated with it. This is very similar to a 'gap', which is an energy that has no allowed states. Such gaps open up, for example, when electrons interact with the lattice. Interestingly only certain electrons `see' this gap. The gap, which should be associated with an insulating state, only exists for electrons travelling parallel to the copper-oxygen bonds. Electrons travelling at 45 degrees to this bond can move freely throughout the crystal. The Fermi surface therefore consists of Fermi Arcs forming pockets centred on the corner of the Brillouin zone. In the pseudogap phase these arcs gradually disappear as the temperature is lowered until only four points on the diagonals of the Brillouin zone remain ungapped. On one hand, this could indicate a completely new electronic phase which consumes available states, leaving only a few to pair up and superconduct. On the other hand, the similarity between this partial gap and that in the superconducting state could indicate that the pseudogap results from preformed cooper pairs. Mechanism The origin of the pseudogap is controversial and still subject to debate in the condensed matter community. Two main interpretations are emerging: 1. The scenario of preformed pairs In this scenario, electrons form pairs at a temperature T* that can be much larger than the critical temperature Tc where superconductivity appears. T* of the order of 300K have been measured in underdoped cuprates where Tc is about 80k. The superconductivity does not appear at T* because large phase fluctuations of the pairing field cannot order at this temperature. The pseudogap is then produced by non coherent fluctuations of the pairing field. 2. The scenario of a non superconducting related pseudogap In this class of scenarios, many different origins have been put forward: like the formation of electronic stripes, antiferromagnetic ordering, exotic order parameter competing with superconductivity. A pseudogap can be seen with several different experimental methods. One of the first observations was in specific heat measurements of YBa2Cu3O6+x by Loram et al.[1] The pseudogap is also apparent in ARPES (Angle Resolved Photoemission Spectroscopy) data, which can measure the density of states of the electrons in a material. References ^J. W. Loram, K. A. Mirza, J. R. Cooper, and W. Y. Liang (1993). "Electronic specific heat of YBa2Cu3O6+x'' from 1.8 to 300 K".Physical Review Letters71 (11): 1740-1743. doi:10.1103/PhysRevLett.71.1740. Emery et al. Physical Review B, Vol 56, Page 6120 (1997) Kyle McElroy, Nature Physics, Vol 2, Page 441 (2006) External links pseudogap in non-superconducting materials:http://www.physorg.com/news10505.html |
2楼2008-03-26 16:59:01
3楼2008-03-26 20:32:12
supersolid226
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4楼2008-03-27 16:54:33
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