Pseudogap state near a quantum critical point
Pseudogap state near a quantum critical point
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DOI：
10.1038/nphys2641
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发表时间：
2013-07-01
期刊：
影响因子：
19.6
通讯作者：
Pepin, C.
中科院分区：
文献类型：
--
作者：
Efetov, K. B.;Meier, H.;Pepin, C.
在量子相变的标准图像中，一个单一的量子临界点在零温度下将相分离。在这里，我们表明，二维的情况是相当复杂的。我们发现，反铁磁体和正常金属之间并不是只有一个点，而是有一个很宽的区域，在这个区域中，磁序被破坏了，但费米面的某些区域却被一个大的间隙所封闭。这个间隙反映了量子态的形成，其特征在于d波超导性和四极密度波的叠加，其建立了一个棋盘图案，其周期与原始自旋密度波的周期不相称。在中等温度下，这两种秩序在相对较大的距离上共存，但热波动破坏了长程秩序。在临界温度以下，涨落就不那么重要了，超导性变得稳定。这一现象可能有助于解释铜氧化物中神秘的赝能隙态和高温超导态转变的起源。特别是，我们表明，光谱探针上的氧和铜网站揭示棋盘秩序。
In the standard picture of a quantum phase transition, a single quantum critical point separates the phases at zero temperature. Here we show that the two-dimensional case is considerably more complex. Instead of the single point separating the antiferromagnet from the normal metal, we have discovered a broad region between these two phases where the magnetic order is destroyed but certain areas of the Fermi surface are closed by a large gap. This gap reflects the formation of a quantum state characterized by a superposition of d-wave superconductivity and a quadrupole density wave, which builds a chequerboard pattern with a period incommensurate with that of the original spin-density wave. At moderate temperatures both orders coexist over comparatively large distances but thermal fluctuations destroy the long-range order. Below a critical temperature the fluctuations are less essential and superconductivity becomes stable. This phenomenon may help to explain the origin of the mysterious pseudogap state and of the high-temperature transition into the superconducting state in the cuprates. In particular, we show that spectroscopic probes on the oxygen and copper sites reveal chequerboard order.