On the basis of ab initio density-functional-theory 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 unusual 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.
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - Nov 6 2008|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics