标题： 强耦合功能重整化群： Hubbard 模型中 Nagaoka 铁磁性和非费米液体物理在$ U = \infty $ 显示英文标题

标题： Strong-coupling functional renormalization group: Nagaoka ferromagnetism and non-Fermi liquid physics in the Hubbard model at $ U = \infty $

摘要： 我们开发了费米子功能重整化群的一个扩展，用于强关联导致投影希尔伯特空间的系统。 我们使用该方法计算无限局域排斥下的哈伯德模型的相图和电子谱函数，在此情况下，涉及双占据格点的多体态被从物理希尔伯特空间中消除。 对于具有最近邻跃迁的正方晶格，我们发现基态从低密度下的顺磁费米液体演变而来，在中间密度下形成具有反铁磁条纹序的状态，最终在高密度下变为扩展的纳加卡铁磁体。 在强关联磁性相中，电子形成无序的非费米液体。 在高密度和低密度下，费米面的体积都不受卢特彻定理的约束。 显示英文摘要

摘要： We develop an extension of the fermionic functional renormalization group for systems where strong correlations give rise to projected Hilbert spaces. We use our method to calculate the phase diagram and the electronic spectral function of the Hubbard model at infinite on-site repulsion where many-body states involving doubly occupied lattice sites are eliminated from the physical Hilbert space. For a square lattice with nearest-neighbor hopping we find that the ground state evolves from a paramagnetic Fermi liquid at low densities via a state with antiferromagnetic stripe order at intermediate densities to an extended Nagaoka ferromagnet at high densities. In the strongly correlated magnetic phases, the electrons form an incoherent non-Fermi liquid. Both at high and low densities, the volume of the Fermi surface is not constrained by Luttinger's theorem.