TiOCl, an orbital-ordered system?

Abstract

We present first-principles density-functional calculations and downfolding studies of the electronic and magnetic properties of the layered quantum spin system TiOCl. We discuss explicitly the nature of the exchange paths and the concept of orbital ordering in this material. An analysis of the electronic structure of slightly distorted structures according to various phonon modes allowed in this material suggests that this system may be subject to orbital fluctuations driven by the electron-phonon coupling.