2025/05/02 by Taisei Kitamura, Hiroki Nakai, Kitamura, Taisei +5 · 4 citations
Computer Science · Engineering · Physics and Astronomy · #Ferromagnetism #Magneto-Optical Properties and Applications #Matrix Theory and Algorithms #Metric (unit) #Nonlinear Waves and Solitons #Point (geometry) #Quantum #Saddle #Saddle point #Singular point of a curve
paper · pdf · doi:10.48550/arxiv.2505.01089
published in arXiv (Cornell University) (Cornell University)
openalex publication_date 2025/05/02 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
We propose ferromagnetism that occurs in electrons at a saddle point with band touching, which we call the singular saddle point. At the singular saddle point, the divergent quantum metric induces ferromagnetic correlation, and the logarithmic divergence of the density of states ensures ferromagnetism within Stoner theory. This is a prototypical example of quantum geometric ferromagnetism. The two-dimensional t2g-orbital model accommodates the ferromagnetism by this mechanism, which is continuously connected to the exactly proven flat-band ferromagnetism.