Itinerant ferromagnetism in Fermi gas Itinerant ferromagnetism(Stoner Mean-field theory, 1936) Ferromagnetic molecular field energy ER=-ISS=--IM whereI is the exchange interaction M is the magnetization• Itinerant ferromagnetism (Stoner Mean-field theory, 1936) Ferromagnetic molecular field energy where is the exchange interaction is the magnetization Itinerant ferromagnetism in Fermi gas