论文标题
小哈伯德集群中伪群的强耦合机制
Strong-coupling mechanism of the pseudogap in small Hubbard clusters
论文作者
论文摘要
在孔掺杂的铜岩中，伪制剂是指在没有超导远距离顺序的情况下，在低能的情况下抑制了状态的密度。哈伯德模型的大量计算显示了单粒子光谱中的伪模，与丘比特的光发射和隧道实验的相似之处引人注目。但是，尚未建立明确的机制。在这里，我们通过精确的对角线化解决了$ 2 \ times2 $簇上的哈伯德模型，并在扭曲的边界条件上进行了集成。在具有以下特征的状态的单粒子密度中发现了一个伪gap：能量尺度和发作温度降低，以增加孔掺杂的孔掺杂，在接近15％的临界孔中闭合，在15 \％的关键孔中，电子掺杂，粒子孔不对称的缺乏，由间隙中心的位置以及$ u/t的强度为$ u/t的位置，以$ u/t的持续存在。研究多体激发光谱表明，单粒子光谱中的伪群是由于裸露的电子和$ u/t \ gtrsim 8 $的最低能量激发之间的正交性。
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 $2\times2$ 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 $U/t \to \infty$. 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 $U/t \gtrsim 8$.
