\textit{Additional} carrier-mediated ferromagnetism in GdN

TL;DR

This paper investigates the ferromagnetic exchange mechanism in GdN, emphasizing the role of carrier density and realistic bandstructure, and proposes a model for carrier-mediated ferromagnetism.

Contribution

It introduces a multiband modified RKKY-like model incorporating realistic bandstructure to analyze carrier-mediated ferromagnetism in GdN.

Findings

Curie temperature varies with carrier density.

Realistic bandstructure influences exchange interactions.

Carrier presence can induce ferromagnetism.

Abstract

The mechanism behind ferromagnetic exchange interaction in GdN is not well understood. It has been argued that it can be due to fourth order cross process of \textit{d-f} mixing and \textit{d-f} exchange. An alternative explanation suggests an anti- ferromagnetic interaction between Gd \textit{d} and N \textit{p} induced moments on the rock salt structure which aligns the nearest neighbor Gd \textit{f} moments ferromagnetically through the \textit{d-f} exchange. In this paper we present results of Curie temperature in GdN as a function of carrier density calculated within our multiband modified RKKY- like exchange interaction. It includes realistic bandstructure of the 5\textit{d} conduction band as an input for single particle energies. We analyze the possibility of carrier- mediated ferromagnetism in GdN and also demonstrate a simple phenomenological model which justifies the role of charge carriers.