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Finite f-electron bandwidth in a heavy-fermion model

机译：重费米子模型中的有限f电子带宽

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摘要

The determinant quantum Monte Carlo (DQMC) method is used to study the effect of nonzero hopping t_f in the "localized" f band of the periodic Anderson model (PAM) in two dimensions. The low-temperature properties are determined in the plane of interband hybridization V and t_f at fixed U_f and half filling, including the case when the sign of t_f is opposite to that of the conduction band t_d. For tf and t_d of the same sign and when t_f/t_d ＞ (V/4t_d)~2, the noninteracting system is metallic. We show that a remnant of the band insulator to metal line at Uf = 0 persists in the interacting system, manifesting itself as a maximal tendency toward antiferromagnetic correlations at low temperature. In this "optimal" t_f region, short-range (e.g., near-neighbor) and long-range spin correlations develop at similar temperatures and have comparable magnitude. Both observations are in stark contrast to the situation in the widely studied PAM (t_f = 0) and single-band Hubbard model, where short-range correlations are stronger and develop at higher temperature. The effect that finite t_f has on Kondo screening is investigated by considering the evolution of the local density of states for selected t_f as a function of V. We use mean-field theory as a tool to discriminate those aspects of the physics that are genuinely many-body in character.
机译：行列式量子蒙特卡罗（DQMC）方法用于研究二维安定周期模型（PAM）的“局部” f波段中非零跳变t_f的影响。低温特性是在带间杂交V和t_f的平面上以固定的U_f和半填充的方式确定的，包括t_f的符号与导带t_d的符号相反的情况。对于相同符号的tf和t_d，并且当t_f / t_d＞（V / 4t_d）〜2时，非相互作用系统是金属的。我们表明，在Uf = 0时，带绝缘子到金属线的残留物在相互作用系统中持续存在，表现为在低温下反铁磁相关性的最大趋势。在该“最佳” t_f区域中，短程（例如，近邻）和长程自旋相关在相似的温度下发展并且具有可比的幅度。两种观察结果与广泛研究的PAM（t_f = 0）和单波段Hubbard模型中的情况形成鲜明对比，后者的短程相关性更强，并在较高温度下发展。通过考虑所选t_f的局部状态密度随V的变化来研究有限t_f对Kondo筛选的影响。我们使用均值场理论作为工具来区分物理学中确实很多方面人物。

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