Dresden 2026 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 21: Electron Theory of Magnetism and Correlations (joint session MA/TT)
TT 21.11: Talk
Monday, March 9, 2026, 17:45–18:00, POT/0151
Coexistence of charge order and antiferromagnetism in three-dimensional Hubbard-Holstein model: A study (exploring phases) at and away from half-filling — •Sandip Halder and Moshe Schechter — Ben-Gurion University of the Negev, Beer-Sheva, Israel
The physics of correlated electron systems has long been explored through the Hubbard model and its extensions, including models with long-range hopping. Likewise, phenomena arising from electron-phonon coupling- such as charge order and superconductivity- have been extensively studied within the Holstein model, though largely in lower dimensions. In transition-metal oxides, however, both electron correlations (U) and electron-phonon coupling (V) coexist intrinsically, motivating a comprehensive study of the Hubbard-Holstein model in three dimensions.
Using an exact diagonalization-based semi-classical Monte Carlo (s-MC) method, we investigate the intriguing properties of this model. At half-filling, the system undergoes a first-order transition between a charge-ordered (CO) phase and an antiferromagnetic (AF) phase as U and V are varied. In the AF regime, near the phase boundary, hole doping drives the system from the AF state (n=1) to a CO state (n=0.5), and eventually to a disordered phase at low densities. Notably, a robust coexistence of AF and CO emerges around x=0.35 (n=0.65), with TCO exceeding TN, consistent with experiments on La2−xSrxNiO4. The study provides new insight into correlated materials and guiding future experimental explorations.
Keywords: Charge Order; Antiferromagnetism; Hubbard-Holstein model; Pseudogap; Mott transition