Microscopic model for transitions from Mott to spin-Peierls insulator in TiOCl

Abstract

On the basis of ab initio density functional theory (DFT) calculations, we derive the underlying microscopic model Hamiltonian for TiOCl, a unique system that shows two consecutive phase transitions from a Mott insulator to a spin-Peierls insulator through a structurally incommensurate phase. We show with our model that the presence of magnetic frustration in TiOCl leads to a competition with the spin-Peierls distortion, which results in the novel incommensurate phase. In addition, our calculations indicate that the spin-Peierls state is triggered by adiabatic phonons, which is essential for understanding the nature of the phase transition.

extended version, accepted in PRB

References in corpus (2)

• Two pressure-induced transitions in TiOCl: Mott insulator to anisotropic metal
• Unusual quasi-one-dimensional electron dispersions in the spin-1/2 quantum magnet TiOCl