Unconventional critical behaviour in a quasi-two-dimensional organic conductor
Unconventional critical behaviour in a quasi-two-dimensional organic conductor
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DOI：
10.1038/nature03806
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发表时间：
2005-07-28
期刊：
影响因子：
64.8
通讯作者：
Kanoda, K
中科院分区：
文献类型：
--
作者：
Kagawa, F;Miyagawa, K;Kanoda, K
改变一个整体中粒子之间的相互作用——例如，通过改变温度或压力——可以导致相变，其临界行为取决于多体系统的集体性质。尽管成分多样，包括原子、分子、电子和它们的自旋，但集体行为可以分为几个家族（称为“普世性类”），由规范自旋模型表示(1)。其中一种跃迁，即莫特跃迁(2)，发生在电子之间的排斥性库仑相互作用增加时，导致波状电子表现为粒子。在二维中，导致高转变温度的氧化铜（3,4）和有机（5-7）化合物的超导性的吸引行为出现在莫特转变附近，但二维排斥电子系统所属的普适类仍然未知。本文用电导测量作为探针，对准二维有机导体中压力诱导莫特跃迁的临界现象进行了观察。我们发现二维中的莫特跃迁与已知的普适性类不一致，因为观察到的集体行为以前没有被看到。在二维莫特跃迁附近的任何紧急行为中都必须包含这种特性。
Changing the interactions between particles in an ensemble-by varying the temperature or pressure, for example-can lead to phase transitions whose critical behaviour depends on the collective nature of the many-body system. Despite the diversity of ingredients, which include atoms, molecules, electrons and their spins, the collective behaviour can be grouped into several families (called 'universality classes') represented by canonical spin models(1). One kind of transition, the Mott transition(2), occurs when the repulsive Coulomb interaction between electrons is increased, causing wave-like electrons to behave as particles. In two dimensions, the attractive behaviour responsible for the superconductivity in high-transition temperature copper oxide(3,4) and organic(5-7) compounds appears near the Mott transition, but the universality class to which two-dimensional, repulsive electronic systems belongs remains unknown. Here we present an observation of the critical phenomena at the pressure-induced Mott transition in a quasi-two-dimensional organic conductor using conductance measurements as a probe. We find that the Mott transition in two dimensions is not consistent with known universality classes, as the observed collective behaviour has previously not been seen. This peculiarity must be involved in any emergent behaviour near the Mott transition in two dimensions.