Kinetic ferromagnetism on a kagome lattice

TL;DR

This paper demonstrates that strongly correlated electrons on a kagome lattice exhibit kinetic ferromagnetism at specific fillings, using an effective Hamiltonian and mathematical theorems to establish magnetic order.

Contribution

It derives an effective Hamiltonian for the system and proves ferromagnetism in the low-temperature limit, extending understanding of magnetic phases in kagome lattice models.

Findings

System is ferromagnetic at low temperatures.

Effective Hamiltonian derived for specific filling fractions.

Robustness of ferromagnetism discussed and extended to other lattices.

Abstract

We study strongly correlated electrons on a kagome lattice at 1/6 and 1/3 filling. They are described by an extended Hubbard Hamiltonian. We are concerned with the limit |t|<<V<<U with hopping amplitude t, nearest-neighbor repulsion V and on-site repulsion U. We derive an effective Hamiltonian and show, with the help of the Perron-Frobenius theorem, that the system is ferromagnetic at low temperatures. The robustness of ferromagnetism is discussed and extensions to other lattices are indicated.