The Jahn-Teller theorem for 3d ions and their compounds

TL;DR

This paper revises the understanding of the Jahn-Teller theorem for 3d ions, emphasizing the importance of considering spin-orbital space rather than just orbital space, and corrects a recent misconception about Jahn-Teller activity.

Contribution

It introduces the necessity of applying the Jahn-Teller theorem in spin-orbital space for 3d ions, challenging previous assumptions that ignored spin-orbit coupling effects.

Findings

Jahn-Teller effect must be considered in spin-orbital space for 3d ions

Corrects a recent claim about Jahn-Teller inactivity in high-spin t2g4eg2 state

Highlights the significance of spin-orbit coupling despite its weakness

Abstract

In contrary to customarily consideration of the Jahn-Teller theorem for 3d-ion compounds in the orbital space only we point out that it has to be considered in the spin-orbital space. It is despite the weakness of the intraatomic spin-orbit coupling. A direct motivation for this paper is an erroneous claim of a recent Phys. Rev. Lett. 96 (2006) 027201 paper that the high-spin t2g4eg2 state of the 3d6 configuration is not Jahn-Teller active.