arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 0711.0624cond-mat.str-elcond-mat.supr-con
收藏

费米晶格模型中的电子关联

Electronic Correlations within Fermionic Lattice Models

M. Matlak, B. Grabiec, S. Krawiec

摘要:

本文研究了广义Hubbard模型中的两格点电子关联。广义Hubbard模型包含了传统的Hubbard模型(参数:$t$(最近邻之间的跳跃),$U$(库仑排斥(吸引)),补充了格点间的库仑相互作用(参数:$J^{(1)}$(平行自旋),$J^{(2)}$(反平行自旋))和格点内Cooper对的跳跃(参数:$V$)。作为第一步,我们发现的本征值$E_α $和本征向量$|E_α>$的二聚体,我们表示每个部分哈密顿量$E_α |E_α > < E_α |$($α=1,2,..,16$)在第二量子化与使用的哈伯德和自旋运营商。每个二聚体能级具有其自己的描述不同的两个网站的相互作用,可以是积极的情况下,只有当水平将被电子占据的哈密顿量。一个典型的特征是出现两个广义的$t-J$相互作用归因于两个不同的能级,甚至对于$% U=J^{(1)}=J^{(2)}=V=0$也不消失,并且在这种情况下它们的耦合常数等于$\pm t$。铁磁性、反铁磁性和超导电性之间的竞争(位内和位间配对)也是该模型的典型特征,因为它在$U=J^{(1)}=J^{(2)}=V=0$和$t\neq 0$的情况下仍然存在。相同类型的电子竞争相互作用分散在不同的能级之间,因此它们的化学活性取决于这些能级的占据。定性地解释了模型相图的来源。我们也考虑一个真正的晶格作为一组相互作用的二聚体,以表明磁性和超导性之间的竞争似乎是普遍的费米子晶格模型。

英文摘要:

We investigate two-site electronic correlations within generalized Hubbard model, which incorporates the conventional Hubbard model (parameters: $t$ (hopping between nearest neighbours), $U$ (Coulomb repulsion (attraction)) supplemented by the intersite Coulomb interactions (parameters: $J^{(1)}$(parallel spins), $J^{(2)}$ (antiparellel spins)) and the hopping of the intrasite Cooper pairs (parameter: $V$). As a first step we find the eigenvalues $E_α $ and eigenvectors $|E_α>$ of the dimer and we represent each partial Hamiltonian $E_α |E_α > < E_α |$ ($α=1,2,..,16$) in the second quantization with the use of the Hubbard and spin operators. Each dimer energy level possesses its own Hamiltonian describing different two-site interactions which can be active only in the case when the level will be occupied by the electrons. A typical feature is the appearence of two generalized $t-J$ interactions ascribed to two different energy levels which do not vanish even for $% U=J^{(1)}=J^{(2)}=V=0$ and their coupling constants are equal to $\pm t$ in this case. The competition between ferromagnetism, antiferromagnetism and superconductivity (intrasite and intersite pairings) is also a typical feature of the model because it persists in the case $U=J^{(1)}=J^{(2)}=V=0$ and $t\neq 0$. The same types of the electronic, competitive interactions are scattered between different energy levels and therefore their thermodynamical activities are dependent on the occupation of these levels. It qualitatively explains the origin of the phase diagram of the model. We consider also a real lattice as a set of interacting dimers to show that the competition between magnetism and superconductivity seems to be universal for fermonic lattice models.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑