Unusual quasi-one-dimensional electron dispersions in the spin-1/2 quantum magnet TiOCl

TL;DR

This study investigates the electronic structure of TiOCl, confirming its quasi-one-dimensional nature and highlighting gaps in current theoretical understanding of its electron dispersions in the normal state.

Contribution

The paper provides polarization-dependent photoelectron spectroscopy data and compares it with theoretical models, revealing discrepancies in understanding TiOCl's electron dispersions.

Findings

Confirmed quasi-one-dimensional electronic structure along the b-axis.

Found no evidence of phonon-induced orbital fluctuations affecting the spin-Peierls transition.

Identified significant gaps between experimental data and theoretical models.

Abstract

We have studied the electronic structure of the spin-1/2 quantum magnet TiOCl by polarization-dependent momentum-resolved photoelectron spectroscopy. From that, we confirm the quasi-one-dimensional nature of the electronic structure along the crystallographic b-axis and find no evidence for sizable phonon-induced orbital fluctuations as origin for the non-canonical phenomenology of the spin-Peierls transition in this compound. A comparison of the experimental data to our own LDA+U and Hubbard model calculations reveals a striking lack of understanding regarding the quasi-one-dimensional electron dispersions in the normal state of this compound.