2025/07/21 by R. David Mayrhofer, Mayrhofer, R. David, Megan Schoenzeit +3
Physics and Astronomy · #Advanced Thermodynamics and Statistical Mechanics #Cold Atom Physics and Bose-Einstein Condensates #FOS: Physical sciences #Quantum, superfluid, helium dynamics #Strongly Correlated Electrons (cond-mat.str-el)
paper · pdf · doi:10.48550/arxiv.2507.16026
openalex publication_date 2025/07/21 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We present the results of a mean-field analysis of the temperature evolution of a ferromagnetic Stoner transition in a two-dimensional (2D) system with an isotropic dispersion εk ∝ k2α, which for α>1 models flat dispersions in various multi-layer graphene systems in a displacement field. This study is an extension to a finite T of previous studies at T=0, which found both first-order and second-order Stoner transitions, depending on the value of α and special behavior at α=1 and α=2. We find that the Stoner transition at a finite T displays new features not seen at T=0. The most interesting one is the reentrant behavior, where the ordered state emerges as temperature is increased. This behavior develops at α>1.4 and the range where it holds increases with α. We conjecture that the reentrant behavior is the fundamental feature of the Stoner transition in 2D, not sensitive to the details of the electronic structure.