Doping control of realization of an extended Nagaoka ferromagnetic state from the Mott state

TL;DR

This paper introduces a model to study the transition from a Mott insulator to a ferromagnetic state inspired by Nagaoka ferromagnetism, revealing phase transitions and magnetic properties through numerical analysis.

Contribution

The paper presents a novel itinerant model with an electron reservoir to emulate doping and explore ferromagnetic transitions from a Mott state.

Findings

Ground-state phase transitions among various total spin states

Emergence of saturated ferromagnetism at finite hole density

Insights into electron distribution and spin correlations

Abstract

Inspired by the Nagaoka ferromagnetism, we propose an itinerant model to study the transition between the Mott singlet state and a ferromagnetic state by emulating a doping process in finite lattices. In the Nagaoka ferromagnetism, the total spin of the system takes the maximum value when an electron is removed from the half-filled system. To incorporate a procedure of the electron removal, our model contains extra sites as a reservoir of electrons, and the chemical potential of the reservoir controls the distribution of electrons. As a function of the chemical potential, the system exhibits ground-state phase transitions among various values of the total spin, including a saturated ferromagnetic state due to the Nagaoka mechanism at finite hole density. We discuss the nature of the ferromagnetism by measuring various physical quantities, such as the distribution of electrons, the spin correlation functions, the magnetization process in the magnetic field, and also the entanglement entropy.