Magnetically Ordered State of Cold Fermions on a Decorated Square Lattice

昌久 古賀, Akihisa Koga

H. Niggemann, J. Zittartz

Kazuto Noda, Akihisa Koga, Norio Kawakami +1 more

We study two-component ultracold fermions with repulsive interactions, which are loaded into a decorated square lattice. By combining the real-space dynamical mean-field theory with the numerical renormalization group method, we discuss magnetic properties in the system. It is clarified how the ferromagnetically ordered ground state, which is stabilized by a flat band mechanism, is adiabatically connected to the ferrimagnetically ordered state expected in the strong coupling limit.

Simone Chiesa, Jie Xu, Shiwei Zhang

Kazuto Noda, Akihisa Koga, Norio Kawakami +1 more

We investigate two-component ultracold fermions loaded into a decorated square lattice, which are described by the Hubbard model with repulsive interactions and nearest-neighbor hoppings. By combining the real-space dynamical mean-field theory with the numerical renormalization-group method, we discuss how a ferromagnetically ordered ground state in the weak-coupling regime, which originates from the existence of a dispersionless band, is adiabatically connected to a Heisenberg ferrimagnetic state in the strong-coupling limit. The effects of level splitting and hopping imbalance are also addressed.

Taku Matsui