Low temperature behavior of itinerant ferromagnet realized in extended Nagaoka mechanism

拡張長岡メカニズムによる遍歴強磁性の低温での性質

大西 弘明  ; 宮下 精二*

Onishi, Hiroaki; Miyashita, Seiji*

We have proposed a Hubbard model which exhibits itinerant ferromagnetism by extending the model of Nagaoka ferromagnetism. In the present work, we confirm that the idea of the realization of itinerant ferromagnetism works in two- and three-dimensional lattices as well as a one-dimensional lattice which we studied previously. We also investigate the temperature dependence of the magnetic ordering and present a magnetic phase diagram in the space of the temperature and the chemical potential. In the obtained phase diagram, we find a V-shape structure for the magnetic ordering near a quantum phase transition. Besides, we find an additional peak exhibiting a dome structure. Temperature dependences of related spin correlation functions are studied in detail.