Magnetic properties of correlated electrons

TL;DR

This paper investigates the magnetic behavior of a system with itinerant electrons and localized spins, revealing metamagnetic phase transitions and detailed magnetization changes under external magnetic fields.

Contribution

It provides a rigorous analysis of the phase diagram and magnetization behavior of the system, focusing on the evolution under external magnetic fields and identifying metamagnetic transitions.

Findings

Metamagnetic phase transitions occur over a wide range of electron densities.

Magnetization jumps of electrons are smaller than those of localized spins.

The phase diagram evolution is characterized using exact ground state energy expressions.

Abstract

We analyze a system composed of itinerant electrons and localized spins with on-site interactions representing the Hund's first rule. Properties of the system are studied rigorously on the infinite square lattice but the configurational space is restricted to the lowest-period phases only. Using exact expressions for the ground state energy an evolution of the phase diagram with an external magnetic field is determined. For a wide range of electron densities metamagnetic phase transitions are detected. It is shown that jumps of magnetization of the electrons at the metamagnetic transitions are much smaller than changes of magnetization of the localized spins.