arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1203.3201cond-mat.str-el
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强关联费米系统中的熵佯谬

Entropy paradox in strongly correlated Fermi systems

J. W. Clark, M. V. Zverev, V. A. Khodel

摘要:

一个由标准朗道费米液体(FL)理论描述的相互作用的相同费米子系统,如果相关性足够强,就可以经历费米表面的重排,就像在有效质量发散的量子临界点发生的那样。到目前为止,这种现象还没有得到充分的理解,但是在量子临界点之外观察到的非费米液体(NFL)行为的突出方面仍然可以在朗道准粒子图像的一般框架内获得。耦合朗道方程的准粒子动量分布$n(p)$和准粒子能谱$ε(p)$的自洽解决方案存在于两个不同的类,取决于耦合强度和准粒子相互作用是正常的或奇异的零动量转移。一类解在零温度下保持标准FL理论的幂等性条件$n^2(p)=n(p)$ $T$,同时向费米面添加口袋。其他解决方案的特点是膨胀的费米面和平坦的频谱$ε(p)$在动量范围内,准粒子occupionlie之间的0和1,即使在T=0。后者,非幂等的解决方案是通过分析的庞加莱映射与基本朗道方程连接$n(p)$和$ε(p)$和验证的变分条件,产生的保留的基态的解决方案。奇怪的是,这个非凡的解决方案携带了大量的温度依赖性过剩熵的负担,直到非常低的温度,威胁违反能斯特定理。有人认为,某些低温相变提供了有效的机制脱落的熵过剩。重费米子化合物的现有测量为这种情况提供了具体的支持。

英文摘要:

A system of interacting, identical fermions described by standard Landau Fermi-liquid (FL) theory can experience a rearrangement of its Fermi surface if the correlations grow sufficiently strong, as occurs at a quantum critical point where the effective mass diverges. As yet, this phenomenon defies full understanding, but salient aspects of the non-Fermi-liquid (NFL) behavior observed beyond the quantum critical point are still accessible within the general framework of the Landau quasiparticle picture. Self-consistent solutions of the coupled Landau equations for the quasiparticle momentum distribution $n(p)$ and quasiparticle energy spectrum $ε(p)$ are shown to exist in two distinct classes, depending on coupling strength and on whether the quasiparticle interaction is regular or singular at zero momentum transfer. One class of solutions maintains the idempotency condition $n^2(p)=n(p)$ of standard FL theory at zero temperature $T$ while adding pockets to the Fermi surface. The other solutions are characterized by a swelling of the Fermi surface and a flattening of the spectrum $ε(p)$ over a range of momenta in which the quasiparticle occupancies lie between 0 and 1 even at T=0. The latter, non-idempotent solution is revealed by analysis of a Poincaré mapping associated with the fundamental Landau equation connecting $n(p)$ and $ε(p)$ and validated by solution of a variational condition that yields the symmetry-preserving ground state. Paradoxically, this extraordinary solution carries the burden of a large temperature-dependent excess entropy down to very low temperatures, threatening violation of the Nernst Theorem. It is argued that certain low-temperature phase transitions offer effective mechanisms for shedding the entropy excess. Available measurements in heavy-fermion compounds provide concrete support for such a scenario.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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