标题： 非刚性空穴带在扩展的t-J模型中 显示英文标题

标题： Non-rigid hole band in the extended t-J model

摘要： 一个在扩展的$t$-$J$模型中，包含对第二和第三近邻的额外跃迁项以及交换部分的挫折项的单个空穴的色散已被研究。 两种方法，一种是描述最小尺寸磁极子的格林函数投影技术，以及对$4*4$晶格的精确对角化，已被应用，显示出彼此之间合理的一致性。 使用对于铜氧化物$_2$平面具有特征的额外跃迁积分，在非挫败情况下，我们在$(\pi/2,\pi/2)$点在$k$-空间中发现色散的各向同性最小值，与最近对绝缘化合物 Sr$_2$CuO$_2$Cl$_2$的角度分辨光电子能谱结果良好一致。 包括挫败效应或有限温度以模拟掺杂的影响，色散发生显著变化，使得在$(\pi/2,0)$和$(\pi,0)$之间可能出现平坦区域和扩展的鞍点，这与最佳掺杂铜氧化物的实验结果一致。 显示英文摘要

摘要： The dispersion of one hole in an extended $t$-$J$ model with additional hopping terms to second and third nearest neighbours and a frustration term in the exchange part has been investigated. Two methods, a Green's function projection technique describing a magnetic polaron of minimal size and the exact diagonalization of a $4*4$ lattice, have been applied, showing reasonable agreement among each other. Using additional hopping integrals which are characteristic for the CuO$_2$ plane in cuprates we find in the nonfrustrated case an isotropic minimum of the dispersion at the point $(\pi/2,\pi/2)$ in $k$-space in good coincidence with recent angle-resolved photoemission results for the insulating compound Sr$_2$CuO$_2$Cl$_2$. Including frustration or finite temperature which shall simulate the effect of doping, the dispersion is drastically changed such that a flat region and an extended saddle point may be observed between $(\pi/2,0)$ and $(\pi,0)$ in agreement with experimental results for the optimally doped cuprates.