论文标题
来自强电子相关的通用集体模式：修改$ 1/\ Mathcal {n} _f $理论，并应用于高 - $ T_C $ cuprates
Universal collective modes from strong electronic correlations: Modified $1/\mathcal{N}_f$ theory with application to high-$T_c$ cuprates
论文作者
论文摘要
开发了一种非零相关的电子晶格系统，结合了变异波函数（VWF）方法的元素和费米子味的逆数（$ 1/\ Mathcal {n} _f $）的膨胀。出发点VWF方法超出了重新归一化的平均场理论，并提供了对高$ T_C $超导蛋糕的主要平衡特性的半定量描述。 VWF+$ 1/\ MATHCAL {n} _F $的开发方案在领先顺序上提供了动态的旋转和电荷响应，围绕VWF解决方案提供了动态的旋转和电荷响应，从而将弱耦合旋转旋转理论推广到了强相关性方案。相关的鞍点状态的热力学校正在连续订单下系统地出现。明确的是，VWF+$ 1/\ MATHCAL {N} _F $用于评估孔掺杂的Hubbard模型的动态响应函数，并将其与可用的量子量子蒙特 - 蒙特 - 卡洛数据进行了比较，从而在相干模式Dynamics的制度中获得了良好的总体协议。明确证明了来自不一致的连续性的明确定义的自旋和电荷激发的出现，并发现了电荷激发能量对相互作用幅度的非单调依赖性。当接近强耦合限制时，电荷模式的能量会缓慢饱和，这要求重新评估$ t $ - $ j $ -model的方法，以使收费动力学有利于更通用的$ t $ - $ j $ - $ j $ - $ u $和$ t $ - $ j $ - $ - $ - $ u $ - $ u $ - $ v $型号。结果也与最新的无弹性共振$ x $ ray和高$ T_C $ cuprates的中子散射实验有关。
A nonzero-temperature technique for strongly correlated electron lattice systems, combining elements of both variational wave function (VWF) approach and expansion in the inverse number of fermionic flavors ($1/\mathcal{N}_f$), is developed. The departure point, VWF method, goes beyond the renormalized mean-field theory and provides semi-quantitative description of principal equilibrium properties of high-$T_c$ superconducting cuprates. The developed here scheme of VWF+$1/\mathcal{N}_f$, in the leading order provides dynamical spin and charge responses around the VWF solution, generalizing the weak-coupling spin-fluctuation theory to the regime of strong correlations. Thermodynamic corrections to the correlated saddle-point state arise systematically at consecutive orders. Explicitly, VWF+$1/\mathcal{N}_f$ is applied to evaluate dynamical response functions for the hole-doped Hubbard model and compared with available determinant quantum-Monte-Carlo data, yielding a good overall agreement in the regime of coherent collective-mode dynamics. The emergence of well-defined spin and charge excitations from the incoherent continua is explicitly demonstrated and a non-monotonic dependence of the charge-excitation energy on the interaction magnitude is found. The charge-mode energy saturates slowly when approaching the strong-coupling limit, which calls for a reevaluation of the $t$-$J$-model approach to the charge dynamics in favor of more general $t$-$J$-$U$ and $t$-$J$-$U$-$V$ models. The results are also related to recent inelastic resonant $X$-ray and neutron scattering experiments for the high-$T_c$ cuprates.
