Universality of pseudogap and emergent order in lightly doped Mott insulators
Universality of pseudogap and emergent order in lightly doped Mott insulators
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DOI：
10.1038/nphys3894
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发表时间：
2017-01-01
期刊：
影响因子：
19.6
通讯作者：
Allan, M. P.
中科院分区：
文献类型：
--
作者：
Battisti, I.;Bastiaans, K. M.;Allan, M. P.
人们普遍认为，铜酸盐的高温超导性源于掺杂莫特绝缘体。当额外的载流子插入母态时，电子变得可移动，但来自莫特态的强相关性被认为能够在不均匀的电子顺序、神秘的赝能隙以及最终出现的超导性中幸存下来。掺杂剂原子的插入如何驱动这种演变尚不清楚，也不知道这些现象是否仅仅是空穴掺杂铜酸盐特有的干扰，或者代表了掺杂莫特绝缘体的真实物理现象。在这里，我们可视化 (Sr1-xLax)(2)IrO4 电子态的演化，它是一种有效的自旋 1/2 莫特绝缘体，与铜酸盐类似，但在化学上完全不同 (2,3)。使用光谱成像扫描隧道显微镜 (SI-STM)，我们发现当掺杂浓度 x 接近 5% 时，会出现不均匀的相分离状态，并在掺杂剂原子簇周围形成赝能隙水坑。在这些水坑中，我们观察到与未掺杂的铜酸盐（1,4-9）中相同的标志性电子顺序。我们研究了这种状态的起源，并找到了低掺杂深度俘获载流子的证据，导致完全带隙的光谱，在 x 接近 4% 的阈值处突然崩溃。我们的结果阐明了莫特态的熔化，并建立了相分离和电子有序作为掺杂莫特绝缘体的一般特征。
It is widely believed that high-temperature superconductivity in the cuprates emerges from doped Mott insulators'. When extra carriers are inserted into the parent state, the electrons become mobile but the strong correlations from the Mott state are thought to survive inhomogeneous electronic order, a mysterious pseudogap and, eventually, superconductivity appear. How the insertion of dopant atoms drives this evolution is not known, nor is whether these phenomena are mere distractions specific to hole-doped cuprates or represent genuine physics of doped Mott insulators. Here we visualize the evolution of the electronic states of (Sr1-xLax)(2)IrO4, which is an effective spin-1/2 Mott insulator like the cuprates, but is chemically radically different(2,3). Using spectroscopic-imaging scanning tunnelling microscopy (SI-STM), we find that for a doping concentration of x approximate to 5%, an inhomogeneous, phase separated state emerges, with the nucleation of pseudogap puddles around clusters of dopant atoms. Within these puddles, we observe the same iconic electronic order that is seen in underdoped cupratesle(1,4-9). We investigate the genesis of this state and find evidence at low doping for deeply trapped carriers, leading to fully gapped spectra, which abruptly collapse at a threshold of x approximate to 4%. Our results clarify the melting of the Mott state, and establish phase separation and electronic order as generic features of doped Mott insulators.