Spectral function of Mott-insulating Hubbard ladders: From fractionalized excitations to coherent quasiparticles
Spectral function of Mott-insulating Hubbard ladders: From fractionalized excitations to coherent quasiparticles
复制标题
DOI：
10.1103/physrevb.99.235117
复制
发表时间：
2019-03
影响因子：
3.7
通讯作者：
Chun-guang Yang;A. Feiguin
中科院分区：
文献类型：
--
作者：
Chun-guang Yang;A. Feiguin
利用含时密度矩阵重整化群方法研究了两支Hubbard阶梯的谱函数。高分辨光谱显示出自旋-电荷分离和散射连续谱的特征，其中束缚态的相干带从散射连续谱中“泄漏”出来，随着腿间跳跃的增加，束缚通道中的连续谱向更高能量移动，自旋和霍隆分支合并成一个单一的相干准粒子带.同时，频谱经历了一个交叉的制度，有两个最小值在无公度值的$k_x$（莫特绝缘体），一个与一个单一的最小值在$k_x=\pi$（带绝缘体）。我们确定了存在的散射状态组成的一个三重子和极化子的连续。我们通过研究空穴产生后真实的空间中电荷和自旋自由度的时间演化，分析了导致准粒子形成的过程。在短时间内，不相干的holon和spinon发射，但经过一个特征时间$\tau$电荷和自旋形式的极化子传播相干。
We study the spectral function of two-leg Hubbard ladders with the time-dependent density matrix renormalization group method (tDMRG). The high-resolution spectrum displays features of spin-charge separation and a scattering continuum of excitations with coherent bands of bound states `leaking' from it. As the inter-leg hopping is increased, the continuum in the bonding channel moves to higher energies and spinon and holon branches merge into a single coherent quasi-particle band. Simultaneously, the spectrum undergoes a crossover from a regime with two minima at incommensurate values of $k_x$ (a Mott insulator), to one with a single minimum at $k_x=\pi$ (a band insulator). We identify the presence of a continuum of scattering states consisting of a triplon and a polaron. We analyze the processes leading to quasiparticle formation by studying the time evolution of charge and spin degrees of freedom in real space after the hole is created. At short times, incoherent holons and spinons are emitted but after a characteristic time $\tau$ charge and spin form polarons that propagate coherently.