Spin-Peierls transition in TiOCl

Titelangaben

Shaz, Mohammad ; van Smaalen, Sander ; Palatinus, Lukas ; Hoinkis, Markus ; Klemm, Matthias ; Horn, Siegfried ; Claessen, Ralph:
Spin-Peierls transition in TiOCl.
In: Physical Review B. Bd. 71 (2005) Heft 10 . - No. 100405.
ISSN 0163-1829
DOI: https://doi.org/10.1103/PhysRevB.71.100405

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Abstract

Temperature-dependent x-ray diffraction of the low-dimensional spin-1∕2 quantum magnet TiOCl shows that the phase transition at Tc2=90K corresponds to a lowering of the lattice symmetry. Below Tc1=66K 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 Tc1 is explained by the competition between the structurally deformed state below Tc2 and the spin-Peierls state below Tc1.