Strong-coupling mechanism of the pseudogap in small Hubbard clusters
Strong-coupling mechanism of the pseudogap in small Hubbard clusters
复制标题
小哈伯德团簇中赝能隙的强耦合机制
DOI：
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
E. Huang
中科院分区：
文献类型：
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作者：
E. Huang
在空穴掺杂的铜氧化物中，赝能隙是指在没有超导长程有序的情况下，在低能量下对态密度的抑制。Hubbard模型的大量计算显示了单粒子光谱中的赝能隙，与铜酸盐的光电发射和隧穿实验有惊人的相似之处。但是，没有建立明确的机制。在这里，我们解决了哈伯德模型2美元 imes 2 $集群的精确对角化，与扭曲的边界条件积分。在单粒子态密度中发现一个赝能隙，其特征是：随着空穴掺杂的增加，能标和起始温度逐渐降低，在空穴掺杂临界值15%附近闭合，电子掺杂时不存在赝能隙，由差距中心的位置表示的粒子-空穴不对称性，以及在强耦合极限$U/t处的持久性 不需要钱。研究多体激发能谱发现，单粒子能谱中的赝能隙是由于裸电子与最低能量激发之间的正交性引起的。
In the hole-doped cuprates, the pseudogap refers to a suppression of the density of states at low energies, in the absence of superconducting long-range order. Numerous calculations of the Hubbard model show a pseudogap in the single-particle spectra, with striking similarities to photoemission and tunneling experiments on cuprates. However, no clear mechanism has been established. Here, we solve the Hubbard model on $2 imes2$ clusters by exact diagonalization, with integration over twisted boundary conditions. A pseudogap is found in the single-particle density of states with the following characteristics: a decreasing energy scale and onset temperature for increased hole-doping, closure at a critical hole doping near 15\%, absence upon electron-doping, particle-hole asymmetry indicated by the location of the gap center, and persistence in the strong-coupling limit of $U/t o infty$. Studying the many-body excitation spectrum reveals that the pseudogap in single-particle spectra is due to orthogonality between bare electrons and the lowest energy excitations for $U/t gtrsim 8$.