Breakdown of the Wiedemann-Franz law in strongly-coupled electron-phonon system, application to the cuprates

被引:10
作者
Lee, KK [1 ]
Alexandrov, AS
Liang, WY
机构
[1] Univ Cambridge, Cavendish Lab, Irc Superconduct, Cambridge CB3 0HE, England
[2] Loughborough Univ Technol, Dept Phys, Loughborough LE11 3TU, Leics, England
关键词
D O I
10.1140/epjb/e2004-00218-6
中图分类号
O469 [凝聚态物理学];
学科分类号
070205 ;
摘要
With the superconducting cuprates in mind, a set of unitary transformations was used to decouple electrons and phonons in the strong-coupling limit. While phonons remain almost unrenormalised, electrons are transformed into itinerent singlet and triplet bipolarons and thermally excited polarons. The triplet/singlet exchange energy and the binding energy of the bipolarons are thought to account for the spin and charge pseudogaps in the cuprates, respectively. We calculated the Hall Lorenz number of the system to show that the Wiedemann-Franz law breaks down due to the interference of the polaron and bipolaron contributions to heat flow. The model provides a quantitative fit to magnetotransport data in the cuprates. Furthermore we are able to extract the phonon component of the thermal conductivity with the use of experimental data and the model. Our results further validate the use of a charged Bose gas model to describe normal and superconducting properties of unconventional superconductors.
引用
收藏
页码:459 / 468
页数:10
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