Incommensurate interactions and non-conventional spin-Peierls transition in TiOBr

TL;DR

This study investigates the incommensurate phase transition in TiOBr using temperature-dependent x-ray diffraction, revealing complex interactions and a transition to a spin-Peierls state at low temperatures.

Contribution

It provides new insights into the incommensurate interactions and the nature of the spin-Peierls transition in TiOBr, highlighting the role of frustration and competing magnetic orders.

Findings

Incommensurate superstructure develops at T_{c2} = 47.1 K.

Lock-in to a two-fold superstructure occurs below T_{c1} = 26.8 K.

Frustration and competition between magnetic orders are key factors.

Abstract

Temperature-dependent x-ray diffraction of the low-dimensional spin 1/2 quantum magnet TiOBr shows that the phase transition at T_{c2} = 47.1 (4) K corresponds to the development of an incommensurate superstructure. Below T_{c1} = 26.8 \pm 0.3 K the incommensurate modulation locks in into a two-fold superstructure similar to the low-temperature spin-Peierls state of TiOCl. Frustration between intra- and interchain interations within the spin-Peierls scenario, and competition between two-dimensional magnetic order and one-dimensional spin-Peierls order are discussed as possible sources of the incommensurability.