CrO2: a self-doped double exchange ferromagnet

TL;DR

This paper uses LSDA+U calculations to explain the metallic ferromagnetism of CrO2, highlighting its double exchange mechanism and potential self-doping due to a small or negative charge transfer gap.

Contribution

It provides a theoretical explanation of CrO2's ferromagnetism based on band structure calculations and proposes the possibility of self-doping in this material.

Findings

CrO2's ferromagnetism is explained by double exchange.

CrO2 likely has a small or negative charge transfer gap.

Self-doping may occur in CrO2 due to its electronic structure.

Abstract

Band structure calculations of CrO2 carried out in the LSDA+U approach reveal a clear picture of the physics behind the metallic ferromagnetic properties. Arguments are presented that the metallic ferromagnetic oxide CrO2 belongs to a class of materials in which magnetic ordering exists due to double exchange (in this respect CrO2 turns out to be similar to the CMR manganates). It is concluded that CrO2 has small or even negative charge transfer gap which can result in self-doping. Certain experiments to check the proposed picture are suggested.