Negative g Factors, Berry Phases, and Magnetic Properties of Complexes

Abstract

It is shown that the sign of the product of three Zeeman splitting factors corresponding to the main magnetic axes defines the sign of the Berry phase of a (pseudo) spin in an applied magneic field. Ab initio calculations show that gXgYgZ<0 is often the case for lanthanide and transition metal complexes, while we prove that it is never achieved in S complexes with dominant second-order magnetic anisotropy. In the case of polynuclear compounds, it is argued that the signs of individual gi, i=X, Y, Z, on each metal site can be extracted from experiment. © 2012 American Physical Society.