On the Possibility of Ferromagnetism and Half-Metallicity in Local Moment Systems

TL;DR

This paper investigates the conditions under which ferromagnetism and half-metallicity can occur in local moment systems using the Kondo lattice model, revealing that ferromagnetism is limited to low band fillings and that temperature induces a transition from half-metal to metal.

Contribution

It introduces a spectral density approach to analyze magnetic phases in the Kondo lattice model, deriving susceptibility and phase diagrams for local moment systems.

Findings

Ferromagnetism occurs only at low band fillings.

Temperature causes a transition from half-metal to metal.

Magnetic phase diagram constructed in T-n plane.

Abstract

We use the Kondo lattice model to investigate the possibility of ferromagnetism and half-metallicity in local moment systems. Using the spectral density approach and making use of the fact that the spontaneous magnetization of local moment and the itinerant electron polarization are coupled, we derive an expression for the paramagnetic susceptibility. The magnetic ordering temperature is determined from the singularities of the susceptibility. The magnetic phase diagram is constructed in $T-n$(band filling) plane. It is found that ferromagnetism is possible only for small values of $n$. It is also found that the temperature drives the transition of the system from half-metal to metal.