Excitonic way to altermagnetism
Jan Kuneš
(Masaryk University, Brno, Czechia)
Collinear magnetic order characterized by zero net magnetization but finite polarization in the reciprocal space - spin texture - has recently been identified in several materials. These so called altermagnets share a number of technologically interesting features with ferromagnets, while retaining the advantages of antiferromagnets. The idea of excitonic condensation and excitonic insulator has been reappearing since the pioneering work of Mott in the early 1960's, most recently in the context of 2D materials revolution.
I will discuss condensation of spinful excitons in the minimal, two orbital, Hubbard model. I will show that doping of the excitonic condensate away from integer filling leads to formation of collinear spin textures. Unlike the textures found in the known altermagnetic materials, the spin textures due to excitonic condensates may exists without ordered atomic moments or even without a finite spin density. The theory will be supported by numerical simulations using dynamical mean-field theory.