2025/05/02 by Taisei Kitamura, Hiroki Nakai, Kitamura, Taisei +5 · 4 citations
Physics and Astronomy · Computer Science · Engineering · #Nonlinear Waves and Solitons #Matrix Theory and Algorithms #Magneto-Optical Properties and Applications
paper · pdf · doi:10.48550/arxiv.2505.01089
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.