Ferromagnetism of cold fermions loaded into a decorated square lattice

TL;DR

This paper explores how ultracold fermions in a decorated square lattice exhibit ferromagnetism, connecting weak coupling ferromagnetic states to strong coupling ferrimagnetic states using advanced theoretical methods.

Contribution

It demonstrates the adiabatic connection between ferromagnetic and ferrimagnetic states in the Hubbard model on a decorated lattice, considering effects of level splitting and hopping imbalance.

Findings

Ferromagnetic ground state arises from a dispersionless band.

Weak coupling ferromagnetism connects to strong coupling ferrimagnetism.

Hopping imbalance influences magnetic ordering.

Abstract

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.