Tanatar Makariy A, Paglione Johnpierre, Petrovic Cedomir, Taillefer Louis
Département de Physique et RQMP, Université de Sherbrooke, Sherbrooke, Canada.
Science. 2007 Jun 1;316(5829):1320-2. doi: 10.1126/science.1140762.
A quantum critical point transforms the behavior of electrons so strongly that new phases of matter can emerge. The interactions at play are known to fall outside the scope of the standard model of metals, but a fundamental question remains: Is the basic concept of a quasiparticle-a fermion with renormalized mass-still valid in such systems? The Wiedemann-Franz law, which states that the ratio of heat and charge conductivities in a metal is a universal constant in the limit of zero temperature, is a robust consequence of Fermi-Dirac statistics. We report a violation of this law in the heavy-fermion metal CeCoIn5 when tuned to its quantum critical point, depending on the direction of electron motion relative to the crystal lattice, which points to an anisotropic destruction of the Fermi surface.
量子临界点对电子行为的改变非常强烈，以至于可能出现新的物质相。已知起作用的相互作用超出了金属标准模型的范围，但一个基本问题仍然存在：准粒子（一种具有重整化质量的费米子）的基本概念在这样的系统中是否仍然有效？维德曼-弗兰兹定律指出，在零温度极限下，金属中的热导率与电导率之比是一个普适常数，这是费米-狄拉克统计的一个有力结果。我们报告称，当重费米子金属CeCoIn5被调谐到其量子临界点时，该定律会被违反，这取决于电子相对于晶格的运动方向，这表明费米面存在各向异性破坏。
