Abstract
X-ray diffraction on TiOCl indicates a temperature-independent -axis unique monoclinic distortion of the crystal lattice of within the incommensurate phase between and . The transition at is described as a first-order phase transition driven by the formation of antiferromagnetic order on the Ti-O bilayers that is governed by the monoclinic lattice distortion. The temperature-dependent incommensurate modulation is considered to represent the growth of the number of spin-Peierls-type singlet pairs on cooling. At , too many electrons have thus been removed from the antiferromagnetic state for it to be stable, and the crystal transforms into the spin-Peierls state.
- Received 31 July 2007
DOI:https://doi.org/10.1103/PhysRevB.77.094117
©2008 American Physical Society