Microscopic theory for the incommensurate transition in TiOCl

Abstract

We propose a microscopic mechanism for the incommensurate phase in TiOX compounds. The model includes the antiferromagnetic chains of Ti ions immersed in the phonon bath of the bilayer structure. Making use of the Cross-Fisher theory, we show that the geometrically frustrated character of the lattice is responsible for the structural instability which leads the chains to an incommensurate phase without an applied magnetic field. In the case of TiOCl, we show that our model is consistent with the measured phonon frequencies at $T=300K$ and the value of the incommensuration vector at the transition temperature. Moreover, we find that the dynamical structure factor shows a progressive softening of an incommensurate phonon near the zone boundary as the temperature decreases. This softening is accompanied by a broadening of the peak which gets asymmetrical as well when going towards the transition temperature. These features are in agreement with the experimental inelastic X-ray measurements.

6 pages, 5 figures. Published version

References in corpus (9)

• S=1/2 chains and spin-Peierls transition in TiOCl
• Spin-Peierls transition in TiOCl
• Nonadiabatic Approach to Spin-Peierls Transitions via Flow Equations
• Zero-field incommensurate spin-Peierls phase with interchain frustration in TiOCl
• Dynamics of the Peierls-active phonon modes in CuGeO_3
• X-ray Scattering Study of the spin-Peierls transition and soft phonon behavior in TiOCl
• Symmetry disquisition on the TiOX phase diagram
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• The spin-Peierls transition beyond the adiabatic approximation

Cited by in corpus (7)

• Electronic structure of the two-dimensional Heisenberg antiferromagnet VOCl: a multi-orbital Mott insulator
• Determination of effective microscopic models for the frustrated antiferromagnets Cs${}_2$CuCl${}_4$ and Cs${}_2$CuBr${}_4$ by density functional methods
• Pressure-driven phase transitions in correlated systems
• Heat conductivity of the spin-Peierls compounds TiOCl and TiOBr
• Theoretical study of the magnetism in the incommensurate phase of TiOCl
• Incommensurate spin Luttinger liquid phase in a model for the spin-Peierls materials TiOBr and TiOCl
• Relevance of nonadiabatic effects in TiOCl