Abstract
Temperature-dependent x-ray diffraction of the low-dimensional spin- quantum magnet TiOCl shows that the phase transition at corresponds to a lowering of the lattice symmetry. Below a twofold superstructure develops, that indicates the formation of spin-singlet pairs via direct exchange between neighboring Ti atoms, while the role of superexchange is found to be negligible. TiOCl thus is identified as a spin-Peierls system of pure one-dimensional chains of atoms. The first-order character of the transition at is explained by the competition between the structurally deformed state below and the spin-Peierls state below .
- Received 18 January 2005
DOI:https://doi.org/10.1103/PhysRevB.71.100405
©2005 American Physical Society