Evolution of the pseudogap from Fermi arcs to the nodal liquid
Evolution of the pseudogap from Fermi arcs to the nodal liquid
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DOI：
10.1038/nphys334
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发表时间：
2006-07-01
期刊：
影响因子：
19.6
通讯作者：
Campuzano, J. C.
中科院分区：
文献类型：
--
作者：
Kanigel, A.;Norman, M. R.;Campuzano, J. C.
材料对外部刺激的响应取决于其低能激发。在传统金属中，这些激发是费米表面上的电子，费米表面是动量 (k) 空间中的轮廓，包含非相互作用电子的所有占据状态。然而，氧化铜超导体中的赝能隙相是一种最不寻常的物质状态(1)。它是金属的，但其费米表面的一部分是“有间隙的”（参考文献 2,3）；低能电子激发占据被称为费米弧 (4) 的断开部分。人们对其起源提出了两种主要解释：赝能隙要么是超导性的前身(5)，要么它源于与超导性竞争的另一种秩序(6)。使用角度分辨光电子能谱，我们表明 k 空间中赝能隙的各向异性以及由此产生的弧仅取决于比率 T/T*(x)，其中 T*(x) 是在给定空穴掺杂 x 下赝能隙首次形成的温度。电弧随 T/T*( x) 线性塌缩，并外推至零程度，即 T --> 0。这表明 T = 0 赝能隙态是一种节点液体 - 一种奇怪的金属态，其无带隙激发仅存在于 k 空间中的点，就像在 d 波超导态中一样。
The response of a material to external stimuli depends on its low-energy excitations. In conventional metals, these excitations are electrons on the Fermi surface - a contour in momentum (k) space that encloses all of the occupied states for non-interacting electrons. The pseudogap phase in the copper oxide superconductors, however, is a most unusual state of matter(1). It is metallic, but part of its Fermi surface is 'gapped out' (refs 2,3); low-energy electronic excitations occupy disconnected segments known as Fermi arcs(4). Two main interpretations of its origin have been proposed: either the pseudogap is a precursor to superconductivity(5), or it arises from another order competing with superconductivity(6). Using angle-resolved photoemission spectroscopy, we show that the anisotropy of the pseudogap in k-space and the resulting arcs depend only on the ratio T/T*(x), where T*( x) is the temperature below which the pseudogap first develops at a given hole doping x. The arcs collapse linearly with T/T*( x) and extrapolate to zero extent as T --> 0. This suggests that the T = 0 pseudogap state is a nodal liquid - a strange metallic state whose gapless excitations exist only at points in k-space, just as in a d-wave superconducting state.