2009/03/19 by A. Honecker, Oleg Derzhko, O. Derzhko +2
Physics and Astronomy · #Advanced Chemical Physics Studies #Advanced Condensed Matter Physics #Condensed matter physics #Degeneracy (biology) #Electron #Frustration #Ground state #Hubbard model #Physics #Physics of Superconductivity and Magnetism #Quantum mechanics #Sawtooth wave #Specific heat #Statistical physics #cond-mat.str-el
paper · pdf · doi:10.1016/j.physb.2009.07.092
published as Physica B404 (2009) 3316-3319 · 4 pages including 5 figures; to appear in Physica B (proceedings of SCES 2008)
arxiv created 2009/03/19 · openalex publication_date 2009/07/09 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Highly frustrated lattices yield a completely flat lowest single-electron band. Remarkably, exact many-body ground states can be constructed for the repulsive Hubbard model and the t-J model by filling this flat band with localized electron states. This construction leads to a macroscopic ground-state degeneracy. We discuss how to compute these ground-state degeneracies for a certain class of models, including in particular the sawtooth chain. Furthermore, we discuss generic consequences for low-temperature thermodynamic properties, like the appearance of a low-temperature peak in the specific heat. Finally, we present complementary numerical results obtained by exact diagonalization.