Principal Mechanisms Underlying Magnetic Order in Transition Metals and Compounds

Abstract

I discuss principal mechanisms of the effective exchange interaction between magnetic moments of transition element atoms in metals and compounds. The purpose is to present clear-cut physical pictures and well-defined terminology of the mechanisms on the basis of the electronic structures revealed by the first principles calculations. Discussion covers transition metals, alloys and compounds including Nd-Fe-B, magnetic semiconductors, and double perovskites. The mechanisms of the effective exchange interaction are categorized into the double exchange interaction, the p-d exchange interaction due to hybridization and the superexchange interaction. The naming and precise definitions are discussed in their historical context.